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AIRS Version 3.0

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<h3><!-- InstanceBeginEditable name="Page Title" -->AIRS Version 3.0<br />L2 Data Release Documentation
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<!-- InstanceBeginEditable name="Content" --><ul>
<li class="bold"><a href="V3.0_L2_Data_Release_UG.pdf">User's Guide in PDF format</a> </li>
<li class="bold"><a href="V3.0_doc_list.shtml">Ancillary documents referenced by the User's Guide</a></li>
<li class="bold"><a href="V3.0_Validation_Report.pdf">Validation Report of AIRS Core product V3.0</a></li>
<li class="bold"><a href="../airs_val_timeline.shtml">AIRS Product Validation Timeline </a></li>
<li><span class="bold"><a href="../airs_RetQAFlag.shtml">AIRS Level 2 Retrieval Data Quality Assurance Flag</a></span> </li>
</ul>
<hr />
<p><b><br />
<br />
August 11, 2003<br />
<br />
<br />
Edited by:<br />
Edward T. Olsen<br />
<br />
Contributions by:<br />
<br />
Luke Chen, Eric Fetzer, Evan Fishbein, Steve Friedman,<br />
</b><b>Stephanie Granger, Denise Hagan, Mark Hofstadter,<br />
</b><b>Bjorn Lambrigtsen, Sung-Yung Lee, Evan Manning<br />
<br />
</b></p>
<table width="" border="0" cellpadding="5" cellspacing="2">
<tr>
<td><b>TABLE OF CONTENTS</b></td>

</tr>
<tr>
<td><b><a href="#introduction">INTRODUCTION</a></b></td>

</tr>
<tr>
<td><b><a href="#instrument">INSTRUMENT DESCRIPTION AND STATUS</a></b></td>

</tr>
<tr>
<td><a href="#overview">OVERVIEW</a></td>

</tr>
<tr>
<td><a href="#descriptionofinstruments">DESCRIPTION OF INSTRUMENTS</a></td>

</tr>
<tr>
<td><a href="#airsinsu">AIRS</a></td>

</tr>
<tr>
<td><a href="#airsvisnirinsu">AIRS VIS/NIR</a></td>

</tr>
<tr>
<td><a href="#amsu-ainsu">AMSU-A</a></td>

</tr>
<tr>
<td><a href="#hsbinsu">HSB</a></td>

</tr>
<tr>
<td><a href="#relationoffieldsofview">Relation of Fields of View of AIRS/AMSU/HSB</a></td>

</tr>
<tr>
<td><b><a href="#airsprocessingsystem">AIRS SCIENCE PROCESSING SYSTEM</a></b></td>

</tr>
<tr>
<td><a href="#systemoverview">SYSTEM OVERVIEW</a></td>

</tr>
<tr>
<td><a href="#dataprocessing">DATA PROCESSING &#150;VERSION 3.0</a></td>

</tr>
<tr>
<td><a href="#l1aprocessing">LEVEL-1A PROCESSING</a></td>

</tr>
<tr>
<td><a href="#l1bprocessing">LEVEL-1B PROCESSING</a></td>

</tr>
<tr>
<td><a href="#l2processing">LEVEL-2 PROCESSING</a></td>

</tr>
<tr>
<td><a href="#L2CCF">L2 Cloud-Cleared Radiance Product</a></td>

</tr>
<tr>
<td><a href="#L2RET">L2 Standard Product</a></td>

</tr>
<tr>
<td><a href="#L2SUP">L2 Support Product</a></td>

</tr>
<tr>
<td><a href="#browseprocessing">BROWSE PROCESSING</a></td>

</tr>
<tr>
<td><a href="#l1bsummarybrowse">L1B Summary Browse Products</a></td>

</tr>
<tr>
<td><a href="#l2summarybrowse">L2 Summary Browse Products</a></td>

</tr>
<tr>
<td><b><a href="#v3.0releaseofl2datainformation">V3.0 RELEASE OF L2 DATA INFORMATION</a></b></td>

</tr>
<tr>
<td><a href="#disclaimerandquickstartQA">DATA DISCLAIMER AND QUICK START QUALITY ASSURANCE</a></td>

</tr>
<tr>
<td><a href="#datadisclaimer">Data Disclaimer</a></td>

</tr>
<tr>
<td><a href="#quickstartQA">Quick Start Quality Assurance</a></td>

</tr>
<tr>
<td><a href="#AIRS">AIRS</a></td>

</tr>
<tr>
<td><a href="#AIRSIRchannelcharacteristics">AIRS IR channel characteristics</a></td>

</tr>
<tr>
<td><a href="#airsinstrumentstate">Instrument state</a></td>

</tr>
<tr>
<td><a href="#radiometriccalibration">Radiometric calibration</a></td>

</tr>
<tr>
<td><a href="#spectralcalibration">Spectral Calibration</a></td>

</tr>
<tr>
<td><a href="#spatialcalibration">Spatial Calibration</a></td>

</tr>
<tr>
<td><a href="#VISNIR">VIS/NIR</a></td>

</tr>
<tr>
<td><a href="#visnirinstrumentstate">Instrument state</a></td>

</tr>
<tr>
<td><a href="#calibrationandchannel">Radiometric calibration and Channel Characteristics</a></td>

</tr>
<tr>
<td><a href="#pointing">Pointing</a></td>

</tr>
<tr>
<td><a href="#AMSU-A">AMSU-A</a></td>

</tr>
<tr>
<td><a href="#amsu-ainstrumentstate">Instrument state</a></td>

</tr>
<tr>
<td><a href="#amsu-aradiometriccalibration">Radiometric calibration</a></td>

</tr>
<tr>
<td><a href="#amsu-apreliminarypointinganalysis">Preliminary Pointing Analysis using Coastlines</a></td>

</tr>
<tr>
<td><a href="#amsu-arelevantanalysis">Relevant analysis</a></td>

</tr>
<tr>
<td><a href="#amsu-achannelcharacteristics">AMSU-A channel characteristics</a></td>

</tr>
<tr>
<td><a href="#HSB">HSB</a></td>

</tr>
<tr>
<td><a href="#hsbinstrumentstate">Instrument state</a></td>

</tr>
<tr>
<td><a href="#hsbradiometriccalibration">Radiometric calibration</a></td>

</tr>
<tr>
<td><a href="#hsbpreliminarypointinganalysis">Preliminary Pointing Analysis using Coastlines</a></td>

</tr>
<tr>
<td><a href="#hsbrelevantanalysis">Relevant analysis</a></td>

</tr>
<tr>
<td><a href="#hsbchannelcharacteristics">HSB channel characteristics</a></td>

</tr>
<tr>
<td><b><a href="#sampledatareaders">SAMPLE IDL-BASED DATA READERS</a></b></td>

</tr>
<tr>
<td><b><a href="#acronyms">ACRONYMS</a></b></td>

</tr>
<tr>
<td><hr size="2" noshade="noshade" /></td>
</tr>
</table>
<p>&nbsp;</p>
<p></p>
<p></p>
<table width="700" border="0" cellspacing="2" cellpadding="0">
<tr>
<td>
<p><a name="introduction" id="introduction">Introduction</a><br />
The Atmospheric Infrared Sounder (AIRS)
instrument suite is designed to measure the Earth&#146;s atmospheric water
vapor and temperature profiles on a global scale. It is comprised of a
space-based hyperspectral infrared instrument (AIRS) and two multichannel
microwave instruments, the Advanced Microwave Sounding Unit (AMSU-A) and the
Humidity Sounder for Brazil (HSB). The AIRS instrument suite is one of several
instruments onboard the Earth Observing System (EOS) Aqua spacecraft launched
May 4, 2002.</p>
<p>The HSB instrument ceased
operation on February 5, 2003. At the time of this writing, investigations into
the possibility of recovering the instrument continue and there will be
periodic attempts to reactivate it. The chance of success is deemed small.</p>
<p>Operational L1B and L2 Products of the AIRS/AMSU/HSB instrument suite on the
EOS Aqua spacecraft are now available for use by the general public. They can
be accessed on the web at the URLs:</p>
<div align="left">
<table width="498" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>EOS Data Gateway</td>
<td><a href="https://reverb.echo.nasa.gov/popup.html">https://reverb.echo.nasa.gov/popup.html</a></td>
</tr>
<tr>
<td>GSFC DAAC Data Pool</td>
<td><a href="/data/datapool/AIRS_DP">http://disc.sci.gsfc.nasa.gov/data/datapool/AIRS_DP</a></td>
</tr>
<tr>
<td>Mirador</td>
<td><a href="http://mirador.gsfc.nasa.gov/cgi-bin/mirador/homepageAlt.pl?keyword=AIRS">http://mirador.gsfc.nasa.gov/cgi-bin/mirador/homepageAlt.pl?keyword=AIRS</a></td>
</tr>

</table>
</div>
<p>These data are in the standard HDF-EOS v4 swath format. See <a href="http://hdf.ncsa.uiuc.edu/rel4links.html">http://hdf.ncsa.uiuc.edu/rel4links.html</a><br />
<p>Only those for which the RetQAFlag is set to zero should be considered for study. Please read the RetQAFlag documentation available at the link:</p>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/V3.0_RetQAFlag.pdf">V3.0_RetQAFlag.pdf</a></b></p>
</div>
<p>All data are released to the public, but only the AIRS and Visible/Near IR radiances are provisionally validated. Please read the disclaimer document:</p>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/V3.0_Data_Disclaimer.pdf">V3.0_Data_Disclaimer.pdf</a></b></p>
</div>
<p>The Level 2 retrieval products are a beta release only in the case of those data that satisfy the following conditions</p>
<ul>
<li>Low Latitude (within the latitude range 40&deg; South to 40&deg; North) </li>
<li>Ocean (land fraction in the AMSU field of view is less than 0.01) </li>
<li>Retrieved SST agrees with NCEP analysis to within 3.0 K </li>
<li>Sun glint avoided (glint distance greater than 200 km) </li>
<li>Full retrieval (MW-Only, FIRST and FINAL stages all acceptable)<br />

</li>
</ul>
<p>Only retrievals satisfying
these conditions should be studied. Researchers can easily limit their
selection of Level 2 data products to those satisfying these conditions by
using the RetQAFlag swath data field in L2 Products. All fields of view whose
RetQAFlag is zero satisfy these criteria.</p>
<p>The initial report covering
the validation of the AIRS/AMSU/HSB products using ECMWF and NCEP reanalysis,
operational buoys, operational radiosondes and AIRS-dedicated radiosondes and
other dedicated observations also defines &#147;Provisional&#148;,
&#147;Beta&#148; and &#147;Validated&#148; states for data and is available at
the link:</p>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/V3.0_Validation_Report.pdf">V3.0_Validation_Report.pdf</a></b></p>
</div>
<div align="left">
<p>Also see the paper:</p>
<p>Fetzer, E., L.
McMillin, D. Tobin, M. Gunson, H. H. Aumann, W. W. McMillan, D. Hagan, M.
Hofstadter, J. Yoe, D. Whiteman, R. Bennartz, J. Barnes, H. V&ouml;mel, V.
Walden, M. Newchurch, P. Minnett, R. Atlas, F. Schmidlin, E. T. Olsen, M. D.
Goldberg, Sisong Zhou, HanJung Ding and H. Revercomb, &#147;AIRS/AMSU/HSB
Validation&#148;, IEEE Trans. Geosci. Remote Sensing, vol. 41, pp. 418-431,
Feb. 2003The</p>
<p>L1B data include
geolocated, calibrated observed radiances, Quality Assessment (QA) data and
global browse images. The radiances are well calibrated; however, not all QA
data have been validated</p>
<p>The L2 data include
geolocated, calibrated cloud-cleared radiances and 2-dimensional and
3-dimensional retrieved physical quantities (e.g., surface properties and
temperature, moisture and ozone profiles throughout the atmosphere). Global
browse images are also included. Each product granule contains 6 minutes of
data. Thus there are 240 granules of each product produced every day.</p>
<p>A complete
description of the contents of the product files may be found in the companion
document titled &#147;AIRS Version 3.0 Released Files Description&#148;. A PDF
file containing Version 1.0 of this document (JPL D-26381), dated June 2003, is
available at the link:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a></b></p>
</div>
<p>The document provides for each product:</p>
<ul>
<li>Dimensions for use in HDF-EOS swath fields (name, value, explanation) </li>
<li>Geolocation fields (name, explanation) </li>
<li>Attributes (name, type, extra dimensions, explanation) </li>
<li>Along-track data fields (name, type, extra dimensions, explanation) </li>
<li>Swath data fields (name, type, extra dimensions, explanation) </li>
<li>Special AIRS types for engineering data fields (name, type, explanation) </li>
</ul>
<p>It also provides the product
file naming and local granule identification (LGID) conventions used in the
identifier portion of the EOSDIS Core System (ECS) and a table of all current
Science, Engineering and Browse Products (L1A, L1B and L2)</p>
<p>Descriptions of the data
products provided in that document and instrument and data features provided
here are limited to the V3.0 released data set. For additional information,
please consult the AIRS public web site:</p>
<p></p>
<div align="center">
<table width="505" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
AIRS Public Web site</div>
</td>
<td>
<div align="center">
<a href="http://www.jpl.nasa.gov/airs">http://www.jpl.nasa.gov/airs</a></div>
</td>
</tr>
</table>
</div>
<p></p>
<p>Additional information may be accessed at the following web sites:</p>
<div align="center">
<table width="511" border="1" cellspacing="2" cellpadding="0">
<tr>
<td><b>AIRS Data Support</b></td>
<td>
<div align="center">

<a href="/AIRS/index.html">http://disc.sci.gsfc.nasa.gov/atmodyn/airs</a></div>
</td>
</tr>
<tr>
<td><b>Aqua AIRS Science</b></td>
<td> <div align="center"><a href="http://airs.jpl.nasa.gov/">http://airs.jpl.nasa.gov/</a> </div></td>
</tr>
<tr>
<td><b>AIRS ATBDs</b></td>
<td>
<div align="center">

<a href="http://eospso.gsfc.nasa.gov/eos_homepage/for_scientists/atbd/viewInstrument.php?instrument=AIRS">Algorithm_Theoretical_Basis_Docs</a></div>
</td>
</tr>
</table>
</div>
<p></p>
<p><b><a name="instrument" id="instrument">Instrument Description and Status</a></b></p>
<p><i><b><a name="overview" id="overview">Overview</a></b></i></p>
<p></p>
<p>The AIRS/AMSU/HSB instrument
suite has been constructed to obtain atmospheric temperature profiles to an
accuracy of 1 K for every 1 km layer in the troposphere and an accuracy of 1 K
for every 4 km layer in the stratosphere up to an altitude of 40 km. The
temperature profile accuracy in the troposphere will match that achieved by
radiosondes launched from ground stations. The advantage of the AIRS suite in
orbit is the provision of rapid global coverage. Radiosonde coverage of the
Earth&#146;s oceans is practically nonexistent. In conjunction with the
temperature profiles, the AIRS instrument suite will obtain humidity profiles
to an accuracy of 10% in 2 km layers from the surface to the tropopause.</p>
<p><b><a name="descriptionofinstruments" id="descriptionofinstruments">Description of Instruments</a></b><br />

The Aqua Instrument Page provides guides to the instruments, including quicktime animations that illustrate their operation:</p>
<p></p>
<div align="center">
<table width="474" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<b>Aqua AIRS Instrument</b></div>
</td>
<td><a href="http://disc.gsfc.nasa.gov/AIRS/instruments.shtml">http://disc.gsfc.nasa.gov/AIRS/instruments.shtml</a></td>
</tr>
<tr>
<td>
<div align="center">
<b>Aqua AMSU Instrument</b></div>
</td>
<td><a href="http://avdc.gsfc.nasa.gov/Links/Data/Satellites/AIRS_AMSU_Data.html">http://www.aqua.nasa.gov/AMSU3.html</a></td>
</tr>
<tr>
<td>
<div align="center">
<b>Aqua HSB Instrument</b></div>
</td>
<td><a href="http://www.inpe.br/programas/hsb/ingl/">http://www.inpe.br/programas/hsb/ingl/</a></td>
</tr>
</table>
</div>
<p></p>
</td>
</tr>
</table>
</div>
<p></p>
<div align="center">

</div>
<div align="center">

</div>
<div align="center">

</div>
<div align="center">
<table width="700" border="0" cellspacing="2" cellpadding="0">
<tr>
<td><b><a name="airsinsu" id="airsinsu">AIRS</a></b>
<p>The AIRS infrared
spectrometer acquires 2378 spectral samples at resolutions, l/Dl, ranging from
1086 to 1570, in three bands: 3.74 &micro;m to 4.61 &micro;m, 6.20 &micro;m to
8.22 &micro;m, and 8.8 &micro;m to 15.4 &micro;m. A 360 degree rotation of the
scan mirror generates a cross-track Earth-scene scan line of IR data every
2.667 seconds. The spatial resolution at nadir is 13.5 km. This instrument
provides fine vertical scale resolution soundings of atmospheric temperature
and water vapor, and integrated column burden for trace gases. Cold space-views
for calibration of data are taken at the beginning and end of the Earth-scene
when the mirror sweeps through space-view scenes.</p>
<p>The IR focal plane is cooled
to 60 K by a Stirling/pulse tube cryocooler. The scan mirror operates at
approximately 265 K due to radiative coupling to the Earth and space and to the
150 K IR spectrometer. Cooling of the IR optics and detectors is necessary to
achieve the required instrument sensitivity.</p>
<p><b><a name="airsvisnirinsu" id="airsvisnirinsu">AIRS VIS/NIR</a></b></p>
<p>
The Visible/Near-IR (VIS/NIR)
photometer contains four spectral bands, each with nine pixels along track,
with a 0.185 degree instantaneous field-of-view (FOV). It is boresighted to the
IR spectrometer to allow simultaneous measurements of the visible and infrared
scene. The VIS/NIR photometer uses optical filters to define four spectral
bands in the 400 nm to 1000 nm region. The VIS/NIR detectors are not cooled and
operate in the 293 K to 300 K ambient temperature range of the instrument
housing. The spatial resolution at nadir is 2.3 km. The primary function of the
AIRS VIS/NIR channels is to provide diagnostic support to the infrared
retrievals: setting flags that warn of the presence of low-clouds or highly
variable surface features within the infrared FOV.</p>
<p><b><a name="amsu-ainsu" id="amsu-ainsu">AMSU-A</a></b></p>
<p>The AMSU-A microwave
multichannel radiometer consists of two physically separate units, AMSU-A1 and
AMSU-A2. Together they have 15 channels, measuring radiation in the frequency
span of 23 GHz to 90 GHz. Twelve channels (between 50 GHz and 60 GHz) are
predominantly used for atmospheric temperature sounding. The remaining three
channels (24 GHz, 31 GHz and 89 GHz) are predominantly used for atmospheric
water vapor sounding. The rotating scanning mirror generates a cross-track scan
line every 8 seconds. The spatial resolution at nadir is 40.5 km</p>
<p><b><a name="hsbinsu" id="hsbinsu">HSB</a></b></p>
<p>The HSB microwave
multichannel radiometer has 4 channels. One channel measures radiation at 150
GHz and the other three are centered on 183.31 GHz.All channels are used for
atmospheric water vapor sounding. The rotating scanning mirror generates a
cross-track scan line every 2.667 seconds. The spatial resolution at nadir is
13.5 km.</p>
<p>HSB ceased operation on
February 5, 2003. We are continuing investigation with the hope of recovering
the instrument at some future date. The impact on AIRS core products
(temperature profile, water vapor profile, ozone burden) is negligible. Some
future research products (cloud liquid water and precipitation) are adversely
effected.</p>
<p><b><a name="relationoffieldsofview" id="relationoffieldsofview">Relation of Fields of View of AIRS/AMSU/HSB</a></b></p>
<p>A granule of data contains
45 scansets, corresponding to 45 cross-track scans of the AMSU-A mirror. The
AMSU-A radiance data sampled in a scanset are combined to create integrated
radiances for 30 contiguous AMSU-A FOVs. An integration encompasses the time
required for the mirror to sweep through an AMSU-A instantaneous FOV. Figure 1
illustrates the retrieval FOV pattern over Southern California that make up
Granule 209 of AIRS/AMSU/HSB products on September 6, 2002</p>
<p></p>
<div align="center">
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image002.jpg" alt="" height="360" width="401" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">


Figure 1: AIRS/AMSU/HSB Footprint Pattern<br />


Sept 6, 2002; Granule 209</div>
</td>
</tr>
</table>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image003.jpg" alt="" height="640" width="640" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">
Figure 2: AIRS/AMSU/HSB Footprint Pattern<br />
Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
central (lat,lon) = (32.6&deg;, -118.1&deg;)</div>
</td>
</tr>
</table>
</div>
<p></p>
<p></p>
</td>
</tr>
</table>
<p></p>
</div>
<div align="center">
<p></p>
</div>
<p></p>
<div align="center">
<table width="700" border="0" cellspacing="2" cellpadding="0">
<tr>
<td>An AMSU-A FOV encompasses 9 AIRS
FOVs (arranged in a 3x3 matrix) and 9 HSB FOVs (arranged in a 3x3 matrix). Each
AIRS footprint encompasses 72 Vis/NIR pixels (arranged in a 9x8 rectangular
array). This arrangement is illustrated in Figure 2, which was produced from
the geolocation information contained within Granule 209 of data taken
September 6, 2002, just off the coast of Southern California. The association
shown comprises those data which are combined into a retrieval field-of-view
located in the 11 th AMSU-A FOV of the 27th AMSU-A scanset. The large circle
represents the 3.3 deg instantaneous FOV of an AMSU-A observation. The smaller
colored circles represent the 1.1 deg instantaneous FOVs of the associated
arrays of AIRS and HSB observations. The colored rectangles represent the areas
covered by the associated arrays of VIS/NIR pixels.
<p>Since granule 209 is an
ascending (daytime) granule, the spacecraft track tends toward the northwest.
The scan direction as seen by an observer sitting on the spacecraft and facing
the direction of motion is left to right. Thus the scan direction on the Earth
for this granule is also left to right in this figure.</p>
<p>Within each scanset are
three scanlines, corresponding to 3 cross-track scans of the AIRS and HSB
mirrors. The AIRS and HSB radiance data sampled in each scanline are combined
to create integrated radiances for 90 AIRS and 90 HSB footprints.</p>
<p>The VIS/NIR instrument has
an array of 9 detectors arranged along the spacecraft track direction that look
at the AIRS mirror. Sampling and integration are arranged so that there are 8
cross-track samples of each VIS/NIR detector as the mirror sweeps through one
AIRS instantaneous FOV.</p>
<p><b><a name="airsprocessingsystem" id="airsprocessingsystem">AIRS Science Processing System</a></b></p>
<p><i><b><a name="systemoverview" id="systemoverview">System Overview</a></b></i></p>
<p>The AIRS Science Processing
System (SPS) is a collection of programs, or Product Generation Executives
(PGEs), used to process AIRS Science Data. These PGEs process raw, low level
AIRS Infrared (AIRS), AIRS Visible (VIS), AMSU, and HSB instrument data to
obtain temperature and humidity profiles.</p>
<p>AIRS PGEs can be grouped
into three distinct processing phases for processing: Level 1A, Level 1B and
Level 2. Each consecutive processing phase yields a higher-level data product.
Levels 1A and 1B result in calibrated, geolocated radiance products. Level 2
processing derives temperature and humidity profiles, and cloud and surface
properties. In addition to the standard processing PGEs, there are additional
Browse PGEs that are run to produce an aggregate qualitative summary for each
standard product and a radiosonde matchup PGE which collects and associates all
AIRS products derived within 100 km and 3 hr of ADP operational upper air
radiosonde launches reported in the National Centers for Environmental
Prediction (NCEP) quality controlled final observation data files (PREPQC).
Figure 3 is a diagram illustrating the processing flow of the AIRS Science
Processing System.</p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image006.gif" alt="" height="289" width="538" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">
<b>Figure 3: AIRS Science Processing System Processing Flow</b></div>
</td>
</tr>
</table>
<p><b><a name="dataprocessing" id="dataprocessing">Data Processing &#150;Version 3.0</a>
</b></p>
<p>The V3.0 Release Science
Processing Software (SPS) provided to the Goddard Space Flight Center (GSFC)
Distributed Active Archive Center (DAAC) for L2 Product Generation is version
3.0.8.0 and represents the best refinement of all Level 1A, Level 1B and Level
2 PGEs as of July 18, 2003. It contains working versions of all Level 1A, Level
1B and Level 2 software modules. Specific features and characteristics of
version 3.0.8.0 are described in other sections of this documentation.</p>
<p>The enhancements to Level 1A
and Level 1B reflect lessons learned from analysis of post-launch data. The
software is still under development, and JPL plans to continue to upgrade PGEs
and will deliver updated code modules to the GSFC DAAC to support public
release of Level 2 products during the middle of 2003 at approximately Launch +
13 months</p>
<p><a name="l1aprocessing" id="l1aprocessing"><b>Level-1A Processing</b></a></p>
<p>AIRS data processing begins
with receipt of Level 0 data from the Earth Observing System (EOS) Data and
Operations System (EDOS). When Level 0 data are received, Level 1A PGEs are
scheduled. The Level 1A PGEs perform basic house keeping tasks such as ensuring
that all the Level 0 data are present and ordering the data into time of
observation synchronization. Once the Level 0 data are organized, algorithms
perform geolocation refinement and conversion of raw Data Numbers to
Engineering Units (DN to EU). Finally, the level 1A data are collected into
granules of data (six minutes of instrument data) and are forwarded to Level 1B
PGEs for further processing.</p>
<p><a name="l1bprocessing" id="l1bprocessing"><b>Level-1B Processing</b></a></p>
<p>Level 1B PGEs receive 240
granules of AIRS (AIRS IR, AIRS VIS, AMSU and HSB) Level 1A EU data and produce
calibrated, geolocated radiance products. Calibration data and calibration
control parameters are analyzed to develop processing specifications for Level
1B processing. Then, the Level 1A data are processed, yielding our Level 1B
standard products. Each type of AIRS Level 1A data is processed by a
specialized Level 1B PGE. Each Level 1B PGE generates 240 granules of Level 1B
standard products.</p>
<p>Level 1B PGEs produce 240
granules of 4 Level 1B standard products and 2 quality assessment (QA) subset
products. Each granule is composed of 45 scansets. The Earth Science Data Type
(ESDT) short names and normal granule sizes are:</p>
<p></p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>Data Set</td>
<td>
<div align="center">
<b>Short Name</b></div>
</td>
<td>
<div align="center">
<b>Granule Size</b></div>
</td>
</tr>
<tr>
<td>L1B AMSU-A brightness temperatures</td>
<td>
<div align="center">
AIRABRAD</div>
</td>
<td>
<div align="center">
0.4 MB</div>
</td>
</tr>
<tr>
<td>L1B HSB brightness temperatures</td>
<td>
<div align="center">
AIRHBRAD</div>
</td>
<td>
<div align="center">
1.6 MB</div>
</td>
</tr>
<tr>
<td>L1B AIRS radiances</td>
<td>
<div align="center">
AIRIBRAD</div>
</td>
<td>
<div align="center">
122.1 MB</div>
</td>
</tr>
<tr>
<td>L1B VIS radiances</td>
<td>
<div align="center">
AIRVBRAD</div>
</td>
<td>
<div align="center">
21.0 MB</div>
</td>
</tr>
<tr>
<td>L1B AIRS QA</td>
<td>
<div align="center">
AIRIBQAP</div>
</td>
<td>
<div align="center">
6.5 MB</div>
</td>
</tr>
<tr>
<td>L1B VIS QA</td>
<td>
<div align="center">
AIRVBQAP</div>
</td>
<td>
<div align="center">
0.9 MB</div>
</td>
</tr>
</table>
<p></p>
<div align="center">
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image008.jpg" alt="" height="576" width="576" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">
Figure 4: Level 1B Microwave Radiances (AMSU-A and HSB)<br />


Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
</div>
</td>
</tr>
</table>
</div>
<p>Figure 4 shows the combined
AMSU and HSB spectra for the example AMSU FOV first introduced in Figure 2.
Channel number is shown along the vertical axes (AMSU to the left and HSB to
the right), and the horizontal axis represents brightness temperature. The AMSU
temperature sounding channels (3-14) are connected with line segments and that
plot can be viewed as a rudimentary representation of the temperature profile.
The lowest channel is affected by the surface, however, which depresses the
brightness temperature relative to the atmospheric temperature for this oceanic
FOV. The nominal weighting functions for the tropospheric channels peak as
follows: surface (#3), 1000 mb (#4), 750 mb (#4), 400 mb (#6), 250 mb (#7), 150
mb (#8) </p>
<p>AMSU channels 1, 2 and 15
are plotted separately as bars, since they are window channels that are
primarily influenced by the surface brightness (i.e. the product of surface
temperature and emissivity). Ocean emissivity is very low for channels 1 and 2,
which causes very low brightness temperatures, even though the SST is
relatively high. Channel 1 is warmer than channel 2 because it is affected by
water vapor and clouds, which elevates the brightness temperature over the
&quot;cold&quot; ocean background. Channel 15 is warmer still, due to a higher
emissivity as well as higher sensitivity to both water vapor and clouds</p>
<p>HSB has 4 channels and 9
FOVs within the single AMSU FOV, resulting in the 9 line plots shown to the
right. The vertical order of the channels reflect the order of the peak in the
weighting function rather than the serial channel number. These channels
essentially reflect the atmospheric temperature near the peaks of the water
vapor/liquid weighting functions. The lowest channel (#2) peaks near the
surface (but is slightly &quot;cooler&quot; than the surface due to the
emissivity). The highest channel (#3), which is too opaque to have much
influence from the surface, has a brightness temperature somewhere between AMSU
channels 4 and 5, which suggests it peaks at perhaps 850 mb. The spread between
the 9 plots suggests there is some (but not much) variability in water vapor
and liquid water.</p>
<p>Figure 5 shows the infrared
Level 1B radiance spectra (AIRS) from the example FOV, which contains 9 AIRS
spots. These data are contained in the L1B AIRS Radiance Product</p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image010.jpg" alt="" height="576" width="576" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">
Figure 5: Level 1B Infrared Radiance Spectra (AIRS)<br />


Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
</div>
</td>
</tr>
</table>
<p></p>
<div align="center">

</div>
<p>The brightness temperature
in the 900 cm-1 region varies from around 260K to just under 290K. The AMSU
footprint is over ocean and relatively uniform with the exception of cloud
properties. Thus the variability of brightness temperature is mostly due to the
effect of clouds. Cloud-clearing in the Level 2 retrieval estimates the clear
column radiance from the cloud radiances by extrapolation. Note the slope of
the coldest spectrum (color-coded brown) in the 900 cm-1 region. Since cloud
tops tend to be colder than the surface, this is most likely the cloudiest of
the nine AIRS footprints. The slope is one of the signatures of cirrus clouds.
This spectrum appears to reflect more solar radiance than other AIRS spectra
(i.e., higher brightness temperature in 2600 cm-1 region).</p>
<p>The AIRS Calibration Team
documents the required inputs and outputs of the AIRS IR and VIS/NIR Level 1B
processing software, algorithms for converting AIRS IR digital values to
calibrated radiances, and QA algorithms and indicators in &#147;Atmospheric
Infrared Sounder (AIRS) Level 1B Visible, Infrared and Telemetry Algorithms and
Quality Assessment (QA) Processing Requirements.&#148; Version 2.2 of this
document, dated 2/14/03, is available at the link</p>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l1b/L1B_req_v2.2.pdf">L1B_req_v2.2.pdf</a></b></p>
<p>The interested user
will find additional information on QA indicators for AIRS IR and VIS/NIR L1B
products in this document.</p>
</div>
<div align="left">
<p>Experience with
on-orbit AIRS data prompted the AIRS Calibration Team to alter some AIRS L1B
algorithms (e.g. AutomaticQAFlag, DC Restore, pop detection, Moon-in-view,
offset, noise estimation and gain). A brief AIRS Design File Memo describing
these changes, dated 2/4/03, is available at the link</p>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l1b/l1bqa_changes.pdf">l1bqa_changes.pdf</a></b></p>
</div>
<div align="left">
<p>An AIRS
Design File Memo (ADF-579) provides the initial assessment of the on-orbit
performance of the VIS/NIR system, dated 6/12/02. It is available at the
link:</p>
</div>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l1b/VisInitialCheckout_.pdf">VisInitialCheckout_pdf</a></b></p>
</div>
<p>Another AIRS Design File
Memo (ADF-590-REVISED) dated 9/27/02 provides the results of the first accurate
determination of instrument gains of the VIS/NIR detectors on-orbit via
vicarious calibration in conjunction with the MISR-Terra Calibration Team
operations at Railroad Valley Playa, Nevada. It is available at the link:</p>
<div align="center">
<p><b>
<a href="/AIRS/documentation/airs_l1b/VisGainCalibration.pdf">VisGainCalibration.pdf</a></b></p>
</div>
<div align="left">
<p>The visible/near infrared data provide diagnostic support to the infrared retrievals as well as several research products. The field of radiances from the four channels can be combined to produce a low-resolution false color image of a granule. Figure 6 is an example, showing the entire granule from which the data of Figures 4 and 5 were taken.</p>
<p></p>
</div>
<div align="center">
<p><img src="/AIRS/images/image012.jpg" alt="" height="645" width="592" border="0" /></p>
<table width="595" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Figure 6: false color image of Sept 6, 2002 Granule 209<br />
constructed from Vis/NIR radiances <br />
red circle outlines example FOV; interior is approximate size of FOV<br />
</div>
</td>
</tr>
</table>
</div>
<div align="left">
<p></p>
<p></p>
<p><a name="l2processing" id="l2processing"><b>Level-2 Processing</b></a><br />
<br />
The single
Level 2 PGE reads corresponding Level 1B data granules from all instruments
(AIRS IR, AIRS VIS, AMSU and HSB), the surface pressure at sea level from the
NCEP forecast and a digital elevation map. Figure 7 is a schematic of the Level
2 algorithm flow. Depending upon tests applied in the main algorithm chain (the
central chain in the diagram), the Level 2 product may be that reported from
the &#147;Final Retrieval&#148; stage, the &#147;Initial Regression&#148; stage
or the &#147;MW-Only Retrieval&#148; stage. Bits in RetQAFlag identify at which
stage the ultimate product originates.</p>
<p>Level 2 produces 240 granules of each of the following AIRS products:</p>
</div>
<div align="center">
<table width="369" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>Data Set</td>
<td>
<div align="center">
Short Name</div>
</td>
<td>
<div align="center">
Granule Size</div>
</td>
</tr>
<tr>
<td>L2 Cloud-cleared radiances</td>
<td>
<div align="center">
AIRI2CCF</div>
</td>
<td>
<div align="center">
25.9 MB</div>
</td>
</tr>
<tr>
<td>L2 Standard Product</td>
<td>
<div align="center">
AIRX2RET</div>
</td>
<td>
<div align="center">
4.8 MB</div>
</td>
</tr>
<tr>
<td>L2 Support Product</td>
<td>
<div align="center">
AIRX2SUP</div>
</td>
<td>
<div align="center">
17.9 MB</div>
</td>
</tr>
</table>
</div>
<div align="left">
<p>as well as daily
global browse maps of selected products which are a selection aid for ordering
data from the GSFC DAAC. Each granule contains the data fields from 1350
retrievals laid out in an array of dimension 30x45, corresponding to the 30
AMSU footprints (cross-track) in each of 45 scansets (along-track).</p>
<p>Please note that the
clear FOV detection algorithms are currently under development. There are
several different clear detection algorithms being refined. They employ
different algorithms depending upon their spatial resolution and spectral
regime. Definitions of many of the clear flags and the thresholds that control
them may be found in the link:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/Clear_Flags.pdf">Clear_Flags.pdf</a></b></p>
</div>
<div align="left">
<p>These clear flags
are not yet incorporated into the algorithms contained in the Level 2
Processing stage. <b>The user is advised to ignore them,</b> for they and the
discriminants that control them are still under development. They are
described in the referenced document only because the user will encounter them
in the products and may be tempted to use them to filter data. The user must
not attempt to use these clear flags and discriminants.</p>
<p></p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<img src="/AIRS/images/image014.gif" alt="" height="816" width="616" border="0" /></div>
</td>
</tr>
<tr>
<td>
<div align="center">
Figure 7: AIRS Level 2 Algorithm Flow</div>
</td>
</tr>
</table>
<p><b><a name="L2CCF" id="L2CCF">L2 Cloud-Cleared Radiance Product</a></b></p>
<p>See pp 67 - 71 of
<a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a> for a complete description. Please note that
values of &#150;9999 (if integer) and &#150;9999.0 (if floating) denote invalid
data.</p>
<p>The geolocation data fields of immediate interest to the user are:</p>
<p></p>
<ul>
<li>Latitude FOV boresight geodetic latitude<br />
(degrees North, -90-&gt;+90), dimension (30,45) </li>
<li> </li>
<li>Longitude FOV boresight geodetic longitude<br />
(degrees East, -180-&gt;+180), dimension (30,45) </li>
<li> </li>
</ul>
<p>The attributes of immediate interest to the user are:
</p>
<ul>
<li>freq frequencies associated with each channel (cm-1),<br />
dimension (2378) </li>
</ul>
<p>This is a set of
channel frequencies dynamically determined by the Level 1B software. Users are
advised to use the fixed channel frequencies in the relevant channel properties
file (see page 32 of this document) instead of these.</p>
<p>The swath data fields of immediate interest to user are:</p>
<ul>
<li>RetQAFlag always check this, see <a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a>,dimension (30,45) </li>
<li>radiances calibrated, geolocated channel-by-channel AIRS infrared spectra that would have been observed within each AMSU footprint if there were no clouds in the FOV (milliWatts/m2/cm-1/steradian), dimension (2378,30,45) </li>
<li>radiance_err estimate of the radiance error, channel-by-channel (milliWatts/m2/cm-1/steradian), dimension (2378,30,45) </li>
<li>solzen solar zenith angle (degrees, 0-&gt;180; daytime if &lt; 85), dimension (30,45) </li>
<li>clear_flag do not use; still under development and not yet validated, dimension (30,45) </li>
</ul>
<p>Where the combined
microwave/infrared retrieval is complete (bits 0, 1, 2, 3 and 4 of RetQAFlag
are all not set), the radiances data field contains the final product
calibrated, geolocated AIRS infrared spectra.</p>
<p>Where the combined
retrieval is not complete (one or more of RetQAFlag bits 0, 1, 2, 3 and 4 are
set), the radiances data field contains the last AIRS spectrum computed by the
retrieval algorithm. This is an aid to the developers of the algorithm,
providing insight into the stage of the retrieval that rejected the FOV. Users
should ignore radiances from incomplete retrievals.</p>
<p>Figure 8 shows the
AIRS Level 2 cloud-cleared radiance spectrum (radiances) from the example FOV
converted to brightness temperature. These data contained in the L2
Cloud-Cleared Radiance Product.</p>
<div align="center">
<p><img src="/AIRS/images/image016.jpg" alt="" height="614" width="607" border="0" /><br />
</p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Figure 8: Level 2 Cloud-Cleared Infrared Radiance Spectrum (AIRS)<br />
Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
</div>
</td>
</tr>
</table>
</div>
<div align="left">
<p>Figure 9
illustrates the magnitude of the difference between the final Level 2
cloud-cleared radiance spectrum reported for the example FOV and the nine
observed L1B AIRS radiance spectra. The bulk of this difference is due to the
effect of clouds, which is removed during the Level 2 processing. The cloudiest
AIRS footprint was spot #9 (color-coded in Figures 2,4,5 and 8 by brown). The
least cloudy was spot #4 (color-coded in Figures 2,4,5 and 8 by magenta).</p>
</div>
<div align="center">
<p><img src="/AIRS/images/image018.jpg" alt="" height="614" width="607" border="0" /></p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Figure 9: (L2 Cloud-Cleared Spectrum &#150; L1B Observed Spectra)<br />
Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
</div>
</td>
</tr>
</table>
<p></p>
</div>
<div align="left">
<div align="left">
<p><b><a name="L2RET" id="L2RET">L2 Standard Product</a></b></p>
<p>See pp 59 - 65 of <a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a> for a complete description. Please note that values of &#150;9999 (if integer) and &#150;9999.0 (if floating) denote invalid data.</p>
<p>Please read the document that discusses the finer points of AIRS products defined on levels, layers, TOA and surface.</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/AIRS_L2_levels_and_layers.pdf">AIRS_L2_levels_and_layers.pdf</a></b></p>
</div>
<div align="left">
<p>The geolocation data fields of immediate interest to the user are:</p>
<ul>
<li>Latitude FOV boresight geodetic latitude (degrees North, -90-&gt;+90), dimension (30,45) </li>
<li>Longitude FOV boresight geodetic longitude (degrees East, -180-&gt;+180), dimension (30,45) </li>
</ul>
<p>The attribute of immediate interest to the user are:</p>
<ul>
<li>pressStd
standard pressure (mb) for each of 28 levels in atmosphere associated with
temperature, moisture and ozone profiles. The array order is from the surface
upward, in conformance with WMO standard. Note that topography may place some
of these levels below the surface, dimension (28) </li>
</ul>
<p>The swath data fields of immediate interest to the user are:</p>
<ul>
<li>RetQAFlag always check this, see <a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a> dimension (30,45) </li>
<li>PsurfStd surface pressure, interpolated from forecast and mean topography of FOV (mb), dimension (30,45) </li>
<li>nSurfStd index of last physically meaningful profile entries. Retrieved profile entries beyond this index are filled with &#150;9999. It may be level just above or just below the surface, dimension (30,45) </li>
<li>TSurfStd retrieved surface skin temperature (K), dimension (30,45) </li>
<li>TSurfAir retrieved surface air temperature (K), dimension (30,45) </li>
<li>totH2Ostd total precipitable water vapor in air column (kg/m2), dimension (30,45) </li>
<li>totO3Std total ozone burden in air column (Dobson Units), dimension (30,45) </li>
<li>TAirStd
retrieved atmospheric temperature profile (K) at the pressStd pressures. Array
values below the surface (index &lt; nSurfStd) may not always be filled with
&#150;9999.0. Always check nSurfStd to avoid invalid TAirStd elements below the
surface, dimension (28,30,45) </li>
<li>H2OMMRStd
retrieved water vapor mass mixing ratio (gm/kg_dry_air). Array values below the
surface (index &lt; nSurfStd) may not always be filled with &#150;9999.0.
Always check nSurfStd to avoid invalid H2OMMRStd elements below the surface,
dimension (28,30,45) </li>
<li>H2OMMRSat
retrieved water vapor saturation mass mixing ratio (gm/kg_dry_air). Array
values below the surface (index &lt; nSurfStd) may not always be filled with
&#150;9999.0. Always check nSurfStd to avoid invalid H2OMMRSat elements below
the surface, dimension (28,30,45) </li>
<li>O3VMRStd
retrieved ozone volume mixing ratio (ppm). Array values below the surface
(index &lt; nSurfStd) may not always be filled with &#150;9999.0. Always check
nSurfStd to avoid invalid O3VMRStd elements below the surface, dimension
(28,30,45) </li>
<li>numHingeSurf
number of IR hinge points for retrieved surface emissivity and reflectivity. It
can be as large as 100. Usually 7, 49 or 51 depending upon the retrieval
outcome. A MW-only retrieval results in 7. A full MW/IR retrieval results in
49. A partial MW/IR retrieval results in 51. dimension (30,45) </li>
<li>freqEmis
Frequencies (cm-1) for retrieved surface emissivity and reflectivity in order
of increasing emissivity. Only the first numHingeSurf are valid, dimension
(100,30,45) </li>
<li>emisIRStd The retrieved spectral IR surface emissivity in order of increasing frequency. Only the first numHingeSurf are valid, dimension (100,30,45) </li>
<li>rhoIRStd The retrieved spectral IR bi-directional surface reflectivity in order of increasing frequency. Only the first numHingeSurf are valid, dimension (100,30,45) </li>
<li>NumCloud number of retrieved cloud layers (= 0, 1 or 2), dimension (30,45) </li>
<li>TcldTopStd retrieved cloud top temperature (K) for each of up to two retrieved cloud layers, uppermost layer first. Use with caution, under development, dimension (2,30,45) </li>
<li>PcldTopStd retrieved cloud top pressure (mb) for each of up to two retrieved cloud layers, uppermost layer first. Use with caution, under development, dimension (2,30,45) </li>
<li>CldFrcStd
retrieved cloud fraction (0-&gt;1) for each AIRS footprint associated with the
retrieval FOV, for each layer. Ignore CldFrcStd values exactly equal to zero.
The current cloud clearing code sometimes yields a false zero result. Values
very near zero, i.e., 0.0001 or greater, are correct. Use with caution, under
development, dimension (2,3,3,30,45) </li>
<li>clear_flag_4um
a flag indicating clear FOV valid over ocean only at night, which is based on
the agreement of the predicted SST using observed AIRS radiance at 2616 cm-1
and 2707 cm-1 and the coherency among the 9 AIRS spots in the FOV at 2616
cm-1,. A value of 1 indicates possibly clear. Ignore, under development,
dimension (3,3,30,45) </li>
<li>clear_flag_11um
a flag indicating clear FOV valid over ocean day and night, which is based on
the agreement of the predicted SST using AIRS 11 um split window test and the
coherency among the 9 AIRS spots in the FOV. A value of 1 indicates possibly
clear. Ignore, under development, dimension (3,3,30,45) </li>
<li>clear_flag a flag indicating clear FOV derived in the final retrieval step. Ignore, under development, dimension (30,45). </li>
</ul>
<p>Figure
10 illustrates representative physical retrieval data fields from the example
FOV. These data are contained in the L2 Standard Product. The upper panels
(left to right) are respectively TAirStd, H2OMMRStd, O3VMRStd, and emisIRStd.
The temperature, moisture and ozone plots also show the estimated errors as
error bars on the points. The temperature plot also includes TcldTopStd and
TsurfStd and their errors. AIRS radiances are relatively insensitive to water
vapor in the stratosphere. The current retrieval algorithm reports a
climatological water vapor profile above the tropopause. A dry layer near 100
mb is occasionally seen, as in the H2OMMRStd panel, and is an artifact of
combining a retrieval in the troposphere with a climatological water vapor
profile in the stratosphere.</p>
<p>The
lower panels give PcldTopStd and TcldTopStd and graphical representations of
CldFrcStd and CldFrcStderr. A completely filled circle would indicate CldFrcStd
= 1.0. The errors are indicated by the size of the arcs. A single cloud
formation (at 429.6 mb) was retrieved, and AIRS spot #9 (color-coded brown) is
indeed the cloudiest. AIRS spot #4 (color coded magenta) is the least
cloudy.</p>
</div>
<div align="center">
<p><img src="/AIRS/images/image020.jpg" alt="" height="461" width="576" border="0" /></p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Figure 10: Data Fields from Level 2 Standard Product<br />
Sept 6, 2002; Granule 209; Scanset 27; Footprint 11<br />
</div>
</td>
</tr>
</table>
</div>
<div align="left">
<p><b><a name="L2SUP" id="L2SUP">L2 Support Product</a></b></p>
<p>See
pp 73 - 87 of <a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a> for a complete description. Please
note that values of &#150;9999 (if integer) and &#150;9999.0 (if floating)
denote invalid data. General users are urged to order the L2 Standard Product.
The L2 Support Product is intended for the knowledgeable, experienced user of
AIRS products. It contains high resolution profiles intended to be used for
computation of radiances, as-yet unimplemented research products and various
parameters and intermediate results used to evaluate and track the progress of
the retrieval algorithm.</p>
<p>Please read the document that discusses the finer points of AIRS products defined on levels, layers, TOA and surface</p>
</div>
<div align="center">
<p><b><a href= "/AIRS/documentation/airs_l2/DOCS/AIRS_L2_levels_and_layers.pdf">AIRS_L2_levels_and_layers.pdf</a></b></p>
</div>
<div align="left">
<p>The geolocation data fields of immediate interest to the user are:</p>
<ul>
<li>Latitude FOV boresight geodetic latitude<br />
(degrees North, -90-&gt;+90), dimension (30,45) </li>
<li>Longitude FOV boresight geodetic longitude<br />
(degrees East, -180-&gt;+180), dimension (30,45) </li>
</ul>
<p>The attribute of immediate interest to the user are</p>
<ul>
<li>pressSupp
standard pressure (mb) for each of 100 levels in atmosphere associated with
temperature, moisture and ozone profiles. The array order is from the top of
atmosphere downward. This is the reverse of pressStd ordering. Note that
topography may place some of these levels below the surface, dimension (100) </li>
</ul>
<p>The swath data fields of immediate interest to the user are:</p>
<ul>
<li>RetQAFlag always check this, see <a href="/AIRS/documentation/airs_l2/DOCS/V3.0_Release_ProcFileDesc.pdf">V3.0_Release_ProcFileDesc.pdf</a> dimension (30,45) </li>
<li>PsurfStd surface pressure, interpolated from forecast and mean topography of FOV (mb), dimension (30,45) </li>
<li>nSurfSup
index of last physically meaningful profile entries. Retrieved profile entries
beyond this index are filled with diagnostic values that may appear to be
physically meaningful but are not. It may be level just above or just below the
surface, dimension (30,45) </li>
<li>TSurfStd retrieved surface skin temperature (K), dimension (30,45) </li>
<li>TSurfAir retrieved surface air temperature (K), dimension (30,45) </li>
<li>TAirSup
retrieved atmospheric temperature profile (K) at the pressSupp pressures. Array
values below the surface (index &lt; nSurfStd) are not physically meaningful.
In particular, the first level below the surface contains an extrapolated
value. Always check nSurfSup to identify this extrapolated. The surface value
(at PsurfStd) must be calculated by interpolating in the log(pressure) domain
between this value and the value in the next level up (index = nSurfSup-1),
dimension (100,30,45) </li>
<li>H2OCDSup
retrieved layer column water vapor (molecules/cm-2). The layer corresponding to
value H2OCDSup(index) is bounded by pressSupp(index) at the bottom and
pressSupp(index-1) at the top. Array values below the surface (index &lt;
nSurfStd) are not physically meaningful. In particular, the first level below
the surface contains an extrapolated value. Always check nSurfSup to identify
this extrapolated. The surface value (at PsurfStd) must be calculated by
interpolating in the log(pressure) domain between this value and the value in
the next level up (index = nSurfSup-1), dimension (100,30,45) </li>
<li>lwCDSup
retrieved layer column cloud liquid water (molecules/cm-2). The layer
corresponding to value lwCDSup(index) is bounded by pressSupp(index) at the
bottom and pressSupp(index-1) at the top. Array values below the surface (index
&lt; nSurfStd) are not physically meaningful. In particular, the first level
below the surface contains an extrapolated value. Always check nSurfSup to
identify this extrapolated. The surface value (at PsurfStd) must be calculated
by interpolating in the log(pressure) domain between this value and the value
in the next level up (index = nSurfSup-1). Missing if HSB instrument is not
operational, dimension (100,30,45) </li>
<li>O3CDSup
retrieved layer column ozone (molecules/cm-2). The layer corresponding to value
O3CDSup(index) is bounded by pressSupp(index) at the bottom and
pressSupp(index-1) at the top. Array values below the surface (index &lt;
nSurfStd) are not physically meaningful. In particular, the first level below
the surface contains an extrapolated value. Always check nSurfSup to identify
this extrapolated. The surface value (at PsurfStd) must be calculated by
interpolating in the log(pressure) domain between this value and the value in
the next level up (index = nSurfSup-1), dimension (100,30,45) </li>
</ul>
<p><b><a name="browseprocessing" id="browseprocessing">Browse Processing</a></b></p>
<div align="left">
<p></p>
</div>
<div align="left">
<p>As
240 granules of Level 1B and Level 2 data are produced for a day, a specialized
set of products, termed Browse Products, are also produced each day for each
Level 1B and Level 2 standard product. Each Browse Product is a simplification
of data found within its associated standard product set. Summary Browse
Products are high-level pictorial representations of AIRS Instrument (AIRS
Infrared, AMSU-A and HSB) data binned in 1&deg;x1&deg; boxes, designed as an
aid to ordering data from the GSFC DAAC or the EOS Data Gateway (EDG). By
viewing AIRS Browse images, users will find it easier to select science
granules that correspond to features of interest. Some users may also find
Summary Browse images to be useful tools in their own right.</p>
<p>The AIRS Browse Products included in the data are:</p>
<p></p>
</div>
<div align="center">
<table width="534" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<b>Data Set</b></div>
</td>
<td>
<div align="center">
<b>Short Name </b></div>
</td>
<td>
<div align="center">
<b>Granule Size </b></div>
</td>
</tr>
<tr>
<td>
<div align="left">
L1B AMSU selected radiances browse</div>
</td>
<td>
<div align="center">
AIRABDBR</div>
</td>
<td>
<div align="center">
0.6 MB</div>
</td>
</tr>
<tr>
<td>
<div align="left">
L1B HSB radiance browse</div>
</td>
<td>
<div align="center">
AIRHBDBR</div>
</td>
<td>
<div align="center">
0.3 MB</div>
</td>
</tr>
<tr>
<td>
<div align="left">
L1B AIRS selected radiances browse</div>
</td>
<td>
<div align="center">
AIRIBDBR</div>
</td>
<td>
<div align="center">
0.4 MB</div>
</td>
</tr>
<tr>
<td>
<div align="left">
L2 Cloud-cleared selected radiances browse</div>
</td>
<td>
<div align="center">
AIRI2DBR</div>
</td>
<td>
<div align="center">
0.4 MB</div>
</td>
</tr>
<tr>
<td>
<div align="left">
L2 retrieval browse</div>
</td>
<td>
<div align="center">
AIRX2DBR</div>
</td>
<td>
<div align="center">
0.6 MB</div>
</td>
</tr>
</table>
<p></p>
</div>
<div align="left">
<p><b><a name="l1bsummarybrowse" id="l1bsummarybrowse">L1B Summary Browse Products</a></b></p>
<p>L1B
Summary Browse Products represent a twice-daily global snapshot of selected
AIRS/AMSU/HSB observed radiances for selected data channels, one for ascending
(daytime) nodes and one for descending (nighttime) nodes. This browse consists
of the following observed radiance products averaged over an AMSU FOV:</p>
<p>Observed AMSU-A Radiances</p>
</div>
<ul>
<div align="left">
<li>Channel 1 23.8 GHz, measures atmospheric temperature </li>
<li>Channel 2 31.4 GHz, measures atmospheric temperature </li>
<li>Channel 3 50.3 GHz, measures atmospheric temperature </li>
<li>Channel 4 52.8 GHz, measures atmospheric temperature </li>
<li>Channel 5 53.596 &plusmn; 1.15 GHz, measures atmospheric temperature </li>
<li>Channel 6 54.4 GHz, measures atmospheric temperature </li>
<li>Channel 7 54.94 GHz, measures atmospheric temperature </li>
<li>Channel 15 89.0 GHz, measures water vapor
</li>
</div>
</ul>
<div align="left">
<p>Observed HSB Radiances</p>
</div>
<ul>
<div align="left">
<li>Channel 2 150.0 GHz, measures water vapor </li>
<li>Channel 3 183.31 &plusmn; 1.0 GHz, measures water vapor </li>
<li>Channel 4 183.31 &plusmn; 3.0 GHz, measures water vapor </li>
<li>Channel 5 183.31 &plusmn; 7.0 GHz, measures water vapor
</li>
</div>
</ul>
<div align="left">
<p>Observed AIRS Radiances</p>
</div>
<ul>
<div align="left">
<li>channel 709.74 cm-1, nadir weighting function peaks at 200mb </li>
<li>channel 1040.14 cm-1, representative of O3 channel </li>
<li>channel 1109.49 cm-1, representative window channel </li>
<li>channel 1304.23 cm-1, representative CH4 channel </li>
<li>channel 1310.06 cm-1, representative H2O channel
</li>
</div>
</ul>
<div align="left">
<p><a name="l2summarybrowse" id="l2summarybrowse"><b>L2 Summary Browse Products</b></a></p>
<p>L2
Summary Browse Products represent a twice-daily global snapshot of selected
retrieval products thought to be most helpful to the user for deciding which
data to order. This browse consists of the following retrieval products within
an AMSU FOV:</p>
<p>Cloud-Cleared AIRS Radiances</p>
</div>
<ul>
<div align="left">
<li>channel 709.74 cm-1, nadir weighting function peaks at 200mb </li>
<li>channel 1040.14 cm-1, representative of O3 channel </li>
<li>channel 1109.49 cm-1, representative window channel </li>
<li>channel 1304.23 cm-1, representative CH4 channel </li>
<li>channel 1310.06 cm-1, representative H2O channel
</li>
</div>
</ul>
<div align="left">
<p>Physical Retrieval</p>
</div>
<ul>
<div align="left">
<li>Percent Cloud Cover </li>
<li>Skin Surface Temperature </li>
<li>Total Water Vapor Burden </li>
<li>Total Ozone Burden </li>
<li>Microwave First Guess Liquid Water Burden </li>
<li>Microwave Rain Rate </li>
<li>Visible Percent Clear (daytime only) </li>
<li>Visible Variability Index (daytime only)
</li>
</div>
</ul>
<div align="left">
<p>The
daily browse products will have gores between the satellite paths where there
is no coverage for that day. Each summary browse product file consists of
several unsigned 8-bit arrays. Each array is a 180 x 360 two-dimensional global
map of the Earth's surface, at 1degree by 1degree resolution, using a
rectilinear projection where each grid cell is bounded by latitude and
longitude lines. The longitudinal extent is from -180.0 degrees to +180.0
degrees, with the prime meridian in the center of the image. Each array element
has a value between 0 and 255 and is a re-scaled representation of a
floating-point number (visible images are integer). The relationship between
pixel value (pv) and input floating point data value (dv) is:</p>
</div>
<div align="center">
<p><img src="/AIRS/images/image023.gif" alt="" width="215" height="44" border="0" /></p>
</div>
<div align="left">
<p></p>
<p>The
files are in HDF RIS8 (8-bit raster) format and for each image within the file
there is an associated color palette. Additionally, for each image there are
descriptive annotations in HDF DFAN format. The annotations consist of image
title, image description, and the minimum, mean, and maximum of the original
data values and the corresponding pixel values. The minimum and maximum of the
original data values may be used to annotate a color bar.</p>
<p><a name="v3.0releaseofl2datainformation" id="v3.0releaseofl2datainformation"><b>V3.0 Release of L2 Data Information</b></a></p>
<p><b><a name="disclaimerandquickstartQA" id="disclaimerandquickstartQA">Data Disclaimer and Quick Start Quality Assurance</a></b></p>
<p><b><a name="datadisclaimer" id="datadisclaimer">Data Disclaimer</a></b></p>
<p>The accompanying file:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/V3.0_Data_Disclaimer.pdf">Data_Disclaimer.pdf</a></b></p>
</div>
<div align="left">
<p>provides
information which affects the availability of data for ordering (i.e., may be
unavailable due to instrument outage or spacecraft maneuvering). It also lists
the known liens against each instrument.</p>
<p><a name="quickstartQA" id="quickstartQA">Quick Start Quality Assurance</a></p>
<p>The accompanying file:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/L1B_QA_Quick_Start.pdf">L1B_QA_Quick_Start.pdf</a></b></p>
</div>
<div align="left">
<p>Is
a guide to the most basic L1B AIRS/AMSU/HSB quality assurance (QA) parameters
that a novice user of AIRS/AMSU/HSB data should access to judge its
quality.</p>
<p>A brief user guide for the selected L1B AIRS Radiance Product QA swath data fields is available at the link:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/Select_AIRS_QA_Fields.pdf">Select_AIRS_QA_Fields.pdf</a></b></p>
</div>
<div align="left">
<p><b><a name="AIRS" id="AIRS">AIRS</a></b></p>
<p><b><a name="AIRSIRchannelcharacteristics" id="AIRSIRchannelcharacteristics">AIRS IR channel characteristics</a></b></p>
<p>The
properties of the 2378 AIRS instrument detectors are individually listed in
self-documenting text files. Some properties of the channels change slowly with
time or discontinuously whenever the instrument is warmed by a spacecraft
safety shutdown or in a defrost cycle. Whenever this occurs, a recalibration
exercise is performed and a new channel properties file is created. Thus a
series of these files will result. The L1B PGE must use the proper one (chosen
by date of properties file and date of data) for initial processing and
reprocessing.</p>
<p>The
file names contain a date, identifying the first date for which they are valid
(and supersede a channel properties file containing an earlier date). As of
this release, there are four such files covering the time period from 8/30/02
to the present. Text versions may be accessed through the following links:</p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
<b>Channel Properties Files</b></div>
</td>
</tr>
<tr>
<td>
<div align="center">
<a href="/AIRS/documentation/airs_l2/DOCS/chan_prop.2002.08.30.v6.6.2.pdf">L2.chan_prop.2002.08.30.v6.6.2.pdf</a></div>
</td>
</tr>
<tr>
<td>
<div align="center">
<a href="/AIRS/documentation/airs_l2/DOCS/chan_prop.2002.09.17.v6.6.3.pdf">L2.chan_prop.2002.09.17.v6.6.3.pdf</a></div>
</td>
</tr>
<tr>
<td>
<div align="center">
<a href="/AIRS/documentation/airs_l2/DOCS/chan_prop.2002.10.22.v6.6.4.pdf">L2.chan_prop.2002.10.22.v6.6.4.pdf</a></div>
</td>
</tr>
<tr>
<td>
<div align="center">
<a href="/AIRS/documentation/airs_l2/DOCS/chan_prop.2003.01.10.v6.6.8.pdf">L2.chan_prop.2003.01.10.v6.6.8.pdf</a></div>
</td>
</tr>
</table>
<p><b><a name="airsinstrumentstate" id="airsinstrumentstate">Instrument state</a></b></p>
<ul>
<li>Instrument is in nominal science mode (instrumentflag OpMode = &#145;Operate&#146;) </li>
<li>The quality of the calibration is judged to be good </li>
</ul>
<p><a name="radiometriccalibration" id="radiometriccalibration">Radiometric calibration</a></p>
<p>Refer to papers:</p>
<p>Pagano,
T.S., Aumann, H.H., Hagan, D.E., and Overoye, K., &#147;Prelaunch and In-Flight
Radiometric calibration of the Atmospheric infrared Sounder (AIRS)&#148;,
&#148;, IEEE Transactions on Geosciences and Remote Sensing, pp 265-273, 41.,
2003</p>
<p>Hagan,
D. and P. Minnett, &#147;AIRS radiance validation over ocean from sea surface
temperature measurements&#148;, IEEE Transactions on Geosciences and Remote
Sensing, pp 432-441, 41., 2003.</p>
<p><b><a name="spectralcalibration" id="spectralcalibration">Spectral Calibration</a></b></p>
<p>Refer to paper:</p>
<p>Gaiser,
S. L., H. H. Aumann, L. L. Strow, S. E. Hannon, and M. Weiler, &#148;In-flight
spectral calibration of the atmospheric infrared sounder (AIRS)&#148;, IEEE
Trans. Geosci. Remote Sensing, vol. 41, pp. 287-297, Feb. 2003</p>
<p><b><a name="spatialcalibration" id="spatialcalibration">Spatial Calibration</a></b></p>
<p>Refer to paper</p>
<p>Gregorich,
D. T. and H. H. Aumann, &#148;Verification of AIRS Boresight Accuracy Using
Coastline Detection&#148;, IEEE Trans. Geosci. Remote Sensing, vol. 41, pp.
298-302, Feb. 2003</p>
<p><b><a name="VISNIR" id="VISNIR">VIS/NIR</a></b></p>
<div align="left">
<p><b><a name="visnirinstrumentstate" id="visnirinstrumentstate">Instrument state</a></b></p>
<ul>
<li>Nominal science mode </li>
</ul>
<p><b><a name="calibrationandchannel" id="calibrationandchannel">Radiometric calibration and Channel Characteristics</a></b></p>
<p>Refer to paper</p>
<p>Gautier,
C., Y. Shiren, L. L. and M. D. Hofstadter, &#148;AIRS vis/near IR
instrument&#148;, IEEE Trans. Geosci. Remote Sensing, vol. 41, pp. 330-342,
Feb. 2003</p>
<p>The
Vis/NIR L1B radiances have been calibrated and validated by vicarious
calibration, as described in AIRS Design File memo ADF-590-Revised dated
9/27/02. It is available at the link:</p>
</div>
<div align="center">
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/VisGainCalibration.pdf">VisGainCalibration.pdf</a></b></p>
</div>
<div align="left">
<p>Field
data collected at the time of this writing, but not yet published, confirms the
radiances are valid to the quoted accuracy: 11% for Channel #1 and 7% for
Channels #2,3 and 4. This accuracy does not apply to the first few samples of
Channel #4 in each scanline. These data have anomalously low values as reported
in the accompanying disclaimer file.</p>
<p></p>
<table width="700" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">

<!-- <a href="(EmptyReference!)"><img src="/atmodyn/airs/graphics/image025.jpg" alt="image025" height="372" width="575" border="0"></a>
-->
</div>
</td>
</tr>
<tr>
<td>Figure 11: The approximate spectral response of the four VIS/NIR channels. The three solid curves are, from left to right, Channels 1, 2, and 3. The dashed curve is the response of Channel 4.</td>
</tr>
</table>
<p>Channel
1 (0.40 to 0.44 &micro;m) is designed to be most sensitive to aerosols.
Channels 2 (0.58 to 0.68 &micro;m) and 3 (0.71 to 0.92 &micro;m) approximate
the response of AVHRR channels 1 and 2, respectively, and are particularly
useful for surface studies. (AVHRR is an imaging instrument currently carried
by NOAA polar orbiting satellites.) Channel 4 has a broadband response (0.49 to
0.94 &micro;m) for energy balance studies</p>
<p><b><a name="pointing" id="pointing">Pointing</a></b></p>
<ul>
<li>Validation of the Vis/NIR pointing is not yet complete, but initial comparisons to other satellite data (Terra MISR and Aqua MODIS instruments) suggests it is accurate to within 0.3 degrees (corresponding to 4 km at nadir). </li>
</ul>
<p>Note:
To reduce the data volume, not every VIS/NIR pixel is geolocated. Instead, only
the four &#147;corner pixels&#148; of the 9x8 grouping associated with each IR
footprint are geolocated. (A bi-linear interpolation can be used to locate the
remaining pixels.) In the data files, four-element arrays called
&#147;cornerlats&#148; and &#147;cornerlons&#148; carry this information. The
first array element is the upper-left pixel when viewing an image aligned with
&#147;up&#148; being North. The second element is the upper-right pixel. The
third and fourth elements refer to the lower-left and lower-right pixels,
respectively.</p>
<p></p>
<p><b><a name="AMSU-A" id="AMSU-A">AMSU-A</a></b></p>
<p><b><a name="amsu-ainstrumentstate" id="amsu-ainstrumentstate">Instrument state</a></b></p>
<ul>
<li>Instrument is in nominal science mode </li>
<li>Both AMSU modules are in the optimal space view position </li>
</ul>
<p><b><a name="amsu-aradiometriccalibration" id="amsu-aradiometriccalibration">Radiometric calibration</a></b></p>
<ul>
<li>The data have been reprocessed with the current best calibration algorithm and calibration parameters. </li>
<li>Calibration accuracy is estimated to be on the order of 1 K </li>
<li>Radiometric sensitivity is better than requirements &#150; see AMSU-A channel characteristics table, below. </li>
<li>The quality of the calibration is judged to be good, but at present there are substantial scan biases. Modeling of the sidelobe pickup is under way to correct these scan biases. </li>
<li>L1B
data contain fields named &#147;antenna_temp&#148; and
&#147;brightness_temp&#148;. Both are well calibrated and without sidelobe
correction in this release. The brightness_temp data field will include
sidelobe correction in a future release. In this release the two fields are
identical. </li>
<li>Channel
7 has additional correlated noise, and should be avoided in applications that
use single measurements, such as comparisons with collocated soundings. It may
be used in applications in which some averaging is done (i.e. gridding/binning
or regional averages) </li>
<li>Channel 6 exhibits additional correlated noise; similar to channel 7 but much smaller </li>
<li>Channel 9 exhibits occasional popping, i.e. the calibration counts suddenly drop and then quickly recover. This typically occurs no more than once per orbit. </li>
<li>Channel 14 may have correlated noise, but it is minor </li>
</ul>
<p><b><a name="amsu-apreliminarypointinganalysis" id="amsu-apreliminarypointinganalysis">Preliminary Pointing Analysis using Coastlines</a></b></p>
<ul>
<li>Valid for channels 1, 2, 3, 15 (window channels) </li>
<li>Pitch error &lt; 10% of FOV (&lt; 4 km at nadir) </li>
<li>Roll Error estimated to be less than 20% of FOV </li>
<li>Yaw error estimated to be less than 30% of FOV at swath edge </li>
</ul>
<p><b><a name="amsu-arelevantanalysis" id="amsu-arelevantanalysis">Relevant analysis</a></b></p>
<ul>
<li>See Accompanying Document: <a href="/AIRS/documentation/airs_l2/DOCS/MW_L1B_Assessment.pdf">MW_L1B_Assessment.pdf</a> which is based upon a status report given to the AIRS Science Team in September 2002 and has been updated as of March 10, 2003. </li>
</ul>
<p><b><a name="amsu-achannelcharacteristics" id="amsu-achannelcharacteristics">AMSU-A channel characteristics</a></b></p>
<p></p>
<table width="629" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Ch</div>
</td>
<td>
<div align="center"></div>
</td>
<td>
<div align="center">
Center freq</div>
</td>
<td>
<div align="center">
Stability</div>
</td>
<td>
<div align="center">
Bandwidth</div>
</td>
<td>
<div align="center">
On-Orbit</div>
</td>
<td>
<div align="center">
T/V</div>
</td>
<td>
<div align="center"></div>
</td>
</tr>
<tr>
<td>
<div align="center">
#</div>
</td>
<td>
<div align="center">
Module</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
NEdT[K]</div>
</td>
<td>
<div align="center">
NEdT[K]</div>
</td>
<td>
<div align="center">
Pol</div>
</td>
</tr>
<tr>
<td>
<div align="center">
1</div>
</td>
<td>
<div align="center">
A2</div>
</td>
<td>
<div align="center">
23800</div>
</td>
<td>
<div align="center">
&plusmn;10</div>
</td>
<td>
<div align="center">
1x270</div>
</td>
<td>
<div align="center">
0.17</div>
</td>
<td>
<div align="center">
0.17</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
2</div>
</td>
<td>
<div align="center">
A2</div>
</td>
<td>
<div align="center">
31400</div>
</td>
<td>
<div align="center">
&plusmn;10</div>
</td>
<td>
<div align="center">
1x180</div>
</td>
<td>
<div align="center">
0.19</div>
</td>
<td>
<div align="center">
0.25</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
3</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
50300</div>
</td>
<td>
<div align="center">
&plusmn;10</div>
</td>
<td>
<div align="center">
1x160</div>
</td>
<td>
<div align="center">
0.21</div>
</td>
<td>
<div align="center">
0.25</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
4</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
52800</div>
</td>
<td>
<div align="center">
&plusmn;5</div>
</td>
<td>
<div align="center">
1x380</div>
</td>
<td>
<div align="center">
0.12</div>
</td>
<td>
<div align="center">
0.14</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
5</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
53596&plusmn;115</div>
</td>
<td>
<div align="center">
&plusmn;5</div>
</td>
<td>
<div align="center">
2x170</div>
</td>
<td>
<div align="center">
0.16</div>
</td>
<td>
<div align="center">
0.19</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
6</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
54400</div>
</td>
<td>
<div align="center">
&plusmn;5</div>
</td>
<td>
<div align="center">
1x380</div>
</td>
<td>
<div align="center">
0.21</div>
</td>
<td>
<div align="center">
0.17</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
7</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
54940</div>
</td>
<td>
<div align="center">
&plusmn;5</div>
</td>
<td>
<div align="center">
1x380</div>
</td>
<td>
<div align="center">
0.21</div>
</td>
<td>
<div align="center">
0.14</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
8</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
55500</div>
</td>
<td>
<div align="center">
&plusmn;10</div>
</td>
<td>
<div align="center">
1x310</div>
</td>
<td>
<div align="center">
0.14</div>
</td>
<td>
<div align="center">
0.16</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
9</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
[f0]=57290.344</div>
</td>
<td>
<div align="center">
&plusmn;0.5</div>
</td>
<td>
<div align="center">
1x310</div>
</td>
<td>
<div align="center">
0.14</div>
</td>
<td>
<div align="center">
0.16</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
10</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
f0&plusmn;217</div>
</td>
<td>
<div align="center">
&plusmn;0.5</div>
</td>
<td>
<div align="center">
2x77</div>
</td>
<td>
<div align="center">
0.19</div>
</td>
<td>
<div align="center">
0.22</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
11</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
f0&plusmn;322.4&plusmn;48</div>
</td>
<td>
<div align="center">
&plusmn;1.2</div>
</td>
<td>
<div align="center">
4x35</div>
</td>
<td>
<div align="center">
0.22</div>
</td>
<td>
<div align="center">
0.24</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
12</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
f0&plusmn;322.4&plusmn;22</div>
</td>
<td>
<div align="center">
&plusmn;1.2</div>
</td>
<td>
<div align="center">
4x16</div>
</td>
<td>
<div align="center">
0.31</div>
</td>
<td>
<div align="center">
0.36</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
13</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
f0&plusmn;322.4&plusmn;10</div>
</td>
<td>
<div align="center">
&plusmn;0.5</div>
</td>
<td>
<div align="center">
4x8</div>
</td>
<td>
<div align="center">
0.43</div>
</td>
<td>
<div align="center">
0.50</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
14</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
f0&plusmn;322.4&plusmn;4.5</div>
</td>
<td>
<div align="center">
&plusmn;0.5</div>
</td>
<td>
<div align="center">
4x3</div>
</td>
<td>
<div align="center">
0.71</div>
</td>
<td>
<div align="center">
0.81</div>
</td>
<td>
<div align="center">
H</div>
</td>
</tr>
<tr>
<td>
<div align="center">
15</div>
</td>
<td>
<div align="center">
A1</div>
</td>
<td>
<div align="center">
89000</div>
</td>
<td>
<div align="center">
&plusmn;130</div>
</td>
<td>
<div align="center">
1x2000</div>
</td>
<td>
<div align="center">
0.10</div>
</td>
<td>
<div align="center">
0.12</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
</table>
<p></p>
<p></p>
<p><b><a name="HSB" id="HSB">HSB</a></b></p>
<p><b><a name="hsbinstrumentstate" id="hsbinstrumentstate">Instrument state</a></b></p>
<ul>
<li>Instrument
was placed in survival mode Feb 5, 2003, and remains as of this writing (March
10, 2003). An anomaly investigation team has concluded that the most likely
failure cause is a bad connection or solder joint in the motor drive
electronics commutation circuit. The symptoms seen on orbit were replicated on
an engineering model. Reactivation of HSB will be attempted periodically, but
the chance of success is small. </li>
</ul>
<p><b><a name="hsbradiometriccalibration" id="hsbradiometriccalibration">Radiometric calibration</a></b></p>
<ul>
<li>The data have been reprocessed with the current best calibration algorithm and calibration parameters. </li>
<li>Calibration accuracy is estimated to be on the order of 1 K </li>
<li>Radiometric sensitivity is better than requirements &#150; see HSB channel characteristics table, below. </li>
<li>The quality of the calibration is judged to be good, but at present there are substantial scan biases. Modeling of the sidelobe pickup is under way to correct these scan biases. </li>
<li>L1B
data contain fields named &#147;<b>antenna_temp</b>&#148; and
&#147;<b>brightness_temp</b>&#148;. Both are well calibrated and without
sidelobe correction in this release. The <b>brightness_temp</b> data field will
include sidelobe correction in a future release. In this release the two fields
are identical </li>
</ul>
<p><b><a name="hsbpreliminarypointinganalysis" id="hsbpreliminarypointinganalysis">Preliminary Pointing Analysis using Coastlines</a></b></p>
<ul>
<li>Valid for channel 2 (window channel) </li>
<li>Pitch error &lt; 10% of FOV (&lt; 1.5 km at nadir) </li>
<li>Roll Error estimated to be less than 20% of FOV </li>
<li>Yaw error estimated to be less than 30% of FOV at swath edge </li>
</ul>
<p><b><a name="hsbrelevantanalysis" id="hsbrelevantanalysis">Relevant analysis</a></b></p>
<ul>
<li>See Accompanying Document: <a href="/AIRS/documentation/airs_l2/DOCS/MW_L1B_Assessment.pdf">MW_L1B_Assessment.pdf </a> which is based upon a status report given to the AIRS Science Team in September 2002 and has been updated as of March 10, 2003 </li>
</ul>
<p>Refer to paper:</p>
<p>Lambrigtsen, B. H., and R. V. Calheiros, &quot;The humidity sounder for Brazil--an international partnership&quot;, IEEE Trans. Geosci. and Remote Sensing, 41, 2, pp 352-361, 2003.</p>
<p></p>
<p><b><a name="hsbchannelcharacteristics" id="hsbchannelcharacteristics">HSB channel characteristics</a></b></p>
<p></p>
<p></p>
</div>
<table width="648" border="1" cellspacing="2" cellpadding="0">
<tr>
<td>
<div align="center">
Ch</div>
</td>
<td>
<div align="center">
Center freq</div>
</td>
<td>
<div align="center">
Stability</div>
</td>
<td>
<div align="center">
Bandwidth</div>
</td>
<td>
<div align="center">
On-Orbit</div>
</td>
<td>
<div align="center">
T/V</div>
</td>
<td>
<div align="center">
Pol</div>
</td>
</tr>
<tr>
<td>
<div align="center">
#</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
[MHz]</div>
</td>
<td>
<div align="center">
NEdT[K]</div>
</td>
<td>
<div align="center">
NEdT[K]</div>
</td>
<td>
<div align="center"></div>
</td>
</tr>
<tr>
<td>
<div align="center">
1</div>
</td>
<td colspan="6">
<div align="center">
AMSU-B channel 1 was not implemented for HSB</div>
</td>
</tr>
<tr>
<td>
<div align="center">
2</div>
</td>
<td>
<div align="center">
150000</div>
</td>
<td>
<div align="center">
&plusmn;100</div>
</td>
<td>
<div align="center">
2x1000</div>
</td>
<td>
<div align="center">
0.58</div>
</td>
<td>
<div align="center">
0.68</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
3</div>
</td>
<td>
<div align="center">
183310&plusmn;1000</div>
</td>
<td>
<div align="center">
&plusmn;50</div>
</td>
<td>
<div align="center">
2x500</div>
</td>
<td>
<div align="center">
0.55</div>
</td>
<td>
<div align="center">
0.57</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
4</div>
</td>
<td>
<div align="center">
183310&plusmn;3000</div>
</td>
<td>
<div align="center">
&plusmn;70</div>
</td>
<td>
<div align="center">
2x1000</div>
</td>
<td>
<div align="center">
0.35</div>
</td>
<td>
<div align="center">
0.39</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
<tr>
<td>
<div align="center">
5</div>
</td>
<td>
<div align="center">
183310&plusmn;7000</div>
</td>
<td>
<div align="center">
&plusmn;70</div>
</td>
<td>
<div align="center">
2x2000</div>
</td>
<td>
<div align="center">
0.28</div>
</td>
<td>
<div align="center">
0.30</div>
</td>
<td>
<div align="center">
V</div>
</td>
</tr>
</table>
<div align="left">
<p></p>
<p></p>
<p><b><a name="sampledatareaders" id="sampledatareaders">Sample IDL-Based Data Readers</a></b></p>
<p>The
AIRS Project releases to the broad scientific community sample data readers
written in Interactive Data Language (IDL) to facilitate user community use of
data products. IDL is an array-oriented data analysis and visualization
environment developed and marketed by Research Systems, Incorporated (RSI) of
Boulder, Colorado.</p>
<p>The
user community must realize that the AIRS Project does not have the resources
to support consultation on these readers. They are being provided as an aid to
give the user community a leg up in using the data. There is no commitment to
provide assistance to the broad user community beyond the release of these
readers</p>
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/read_swath_l2.pro.pdf">read_swath_l2.pro.pdf</a></b></p>
<p><b>reads:</b></p>
<p>Level 2 Standard Product</p>
<p>Level 2 Support Product</p>
<p><b>minimal call sequence:</b></p>
<p>read_swath_l2, pattern, numfp, numline, tai, lat, lon, pres, tair, h2o, ozo, Nsurf, Psurf, RetQAFlag</p>
<p><b>input:</b></p>
<p>pattern path/filename of AIRS L2 product to be read</p>
<p>either Standard or Support Product</p>
<p><b>output:</b></p>
<p>numfp number of AIRS footprints in swath scanline (usually = <b>GeoXTrack</b> = 30)</p>
<p>numline number of AIRS scanlines in swath (usually = <b>GeoTrack</b> = 45)</p>
<p>numpres number of levels in all profiles (i.e., pres, tair, h2o,ozo)</p>
<p>(either StdPressureLev = 28 if Standard Product<br />
or XtraPressureLev = 100 if Support Product)</p>
<p>tai array of AIRS footprint tai ( tai[numfp,numline] ), sec</p>
<p>lat array of AIRS footprint latitudes ( lat[numfp, numline] ), deg</p>
<p>lon array of AIRS footprint longitudes ( lon[numfp, numline] ), deg</p>
<p>pres array of pressure levels ( pres[numpres] ), mb</p>
<p>order is surface upward for Standard Product</p>
<p>order is top of atmosphere downward for Support Product</p>
<p>tair array of air temperature ( tair[numpres, numfp, numline] ), K</p>
<p>h2o array of water vapor profiles ( h2o[numpres, numfp, numline] )</p>
<p>ozo array of ozone profiles ( ozo[numpres, numfp, numline] )</p>
<p>Nsurf array of indices of pressure level of last valid profile entry ( Nsurf[numfp, numline] )</p>
<p>Psurf array of surface pressure ( Psurf[numfp, numline] ), mb</p>
<p>RetQAFlag array of retrieval QA flags ( RetQAFlag[numfp, numline] )</p>
<p><b>expanded call sequence:</b></p>
<p>read_swath_l2_airs, pattern, numfp, numline, tai, lat, lon,</p>
<p>pres, tair, h2o, ozo, Nsurf, Psurf, RetQAFlag</p>
<p>full_swath_data_field_name_1=variable_1_to_hold_it</p>
<p>full_swath_data_field_name_n=variable_n_to_hold_it</p>
<p>where the reader supplied already supports these optional swath data field names: Tsurface, Tsurf_Air, LandFrac, sun_glint_distance, final_clear_flag, invalid, CldFrc, PcldTop, TcldTop, clear_flag_4um, clear_flag_11um, tsurf_forecast, tsurf_dif_11um, spatial_coh_11um, tsurf_diff_4um, spatial_coh_4um, cldfrcvis</p>
<p>The user can add more optional data fields by using the code as an example.</p>
<p></p>
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/read_swath_l1_l2cc_airs.pro.pdf">read_swath_l1_l2cc_airs.pro.pdf</a></b></p>
<p><b>reads</b>:<br />
Level 1B AIRS Radiance Product<br />
Level 2 Cloud-Cleared AIRS Radiance Product</p>
<p><b>minimal call sequence</b>:<br />
read_swath_l1_l2cc_airs, pattern, numfp, numline, tai, lat, lon, rad, solzen</p>
<p><b>input</b>:<br />
pattern path/filename of AIRS L1B product to be read</p>
<p><b>output:<br />
</b>numfp number of AIRS footprints in swath scanline<br />
(usually = <b>GeoXTrack</b> = 90)<br />
numline number of AIRS scanlines in swath<br />
(usually = <b>GeoTrack</b> = 135)<br />
tai array of AIRS footprint tai ( tai[numfp,numline] ), sec<br />
lat array of AIRS footprint latitudes ( lat[numfp, numline] ), deg<br />
lon array of AIRS footprint longitudes ( lon[numfp, numline] ), deg<br />
rad array of AIRS radiances ( rad[Channel, numfp, numline] ),<br />
milliWatts/m**2/cm**-1/sterad where <b>Channel</b> = 2378<br />
solzen array of AIRS footprint solar zenith angles<br />
( solzen[numfp,numline] ), deg</p>
<p>expanded call sequence:<br />
read_swath_l1_l2cc_airs, pattern, numfp, numline, tai, lat, lon, rad, solzen<br />
full_swath_data_field_name_1=variable_1_to_hold_it<br />
full_swath_data_field_name_n=variable_n_to_hold_it<br />
<br />
where the reader supplied already supports these optional swath data field names: RetQAFlag, freq, topog<br />
<br />
The user can add more optional data fields by using the code as an example.<br />
<br />
</p>
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/read_swath_l1_vis.pro.pdf">read_swath_l1_vis.pro.pdf</a></b></p>
<p><b>reads</b>:<br />
Level 1B Visible/NearIR Radiance Product</p>
<p><b>minimal call sequence:</b><br />
read_swath_l1_vis, pattern, cornerlats, cornerlons, rad</p>
<p><b>input:</b><br />
pattern path/filename of VIS L1B product to be read</p>
<p><b>output:</b><br />
cornerlats array of VIS geodetic latitudes at the centers of the pixels at the corners of the IR footprint by channel in degrees north<br />
( cornerlats[GeoTrack, GeoXTrack, GeoLocationsPerSpot,<br />
Channel] ), deg<br />
cornerlons array of VIS geodetic longitudes at the centers of the pixels at the corners of the IR footprint by channel in degrees East<br />
(range from &#150;180 to +180) ( cornerlons[GeoTrack, GeoXTrack, GeoLocationsPerSpot, Channel] ), deg<br />
rad array of VIS radiances<br />
( rad[GeoTrack, GeoXTrack, Channel, SubTrack, SubXTrack] ),<br />
in Watts/m**2/micron/steradian<br />
where <b>Channel </b>= 4, <b>SubTrack</b> = 9, <b>SubXTrack</b> = 8,<br />
<b>GeoTrack</b> = 135, <b>GeoXTrack</b> = 90 and <b>GeoLocationsPerSpot</b> = 4.<br />
The storage order of the <b>GeoLocationsPerSpot</b> (corners) is:<br />
AlongTrack Foreward Edge, CrossTrack ScanStart Edge<br />
AlongTrack Foreward Edge, CrossTrack ScanEnd Edge<br />
AlongTrack Trailing Edge, CrossTrack ScanStart Edge<br />
AlongTrack Trailing Edge, CrossTrack ScanEnd Edge<br />
where foreward edge is the edge of the swath data field closest to the direction the satellite is traveling and scanend edge is the edge of the swath data field closest to the end of a crosstrack scan.<br />
The example reader fills this array with the swath data field named <b>radiances</b></p>
<p>The user can add more optional data fields by using the code as an example.<br />
</p>
<p></p>
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/read_swath_l1_amsu.pro.pdf">read_swath_l1_amsu.pro.pdf</a></b></p>
<p><b>reads:</b><br />
Level 1B AMSU Radiance Product</p>
<p><b>minimal call sequence:<br />
</b>read_swath_l1_amsu, pattern, numfp, numline, tai, lat, lon, rad, solzen</p>
<p><b>input</b>:<br />
pattern path/filename of AMSU L1B product to be read</p>
<p><b>output</b>:<br />
numfp number of AMSU footprints in swath scanline<br />
(usually = GeoXTrack = 30)<br />
numline number of AMSU scanlines in swath<br />
(usually = GeoTrack = 45)<br />
tai array of AMSU footprint tai ( tai[numfp,numline] ), sec<br />
lat array of AMSU footprint latitudes ( lat[numfp, numline] ), deg<br />
lon array of AMSU footprint longitudes ( lon[numfp, numline] ), deg<br />
rad array of AMSU radiances ( rad[Channel, numfp, numline] ), K<br />
where Channel = 15. The example reader fills this array with<br />
the swath data field named brightness_temp<br />
solzen array of AMSU footprint solar zenith angles<br />
( solzen[numfp,numline] ), deg</p>
<p><b>expanded call sequence:</b><br />
read_swath_l1_amsu, pattern, numfp, numline, tai, lat, lon, rad, solzen<br />
full_swath_data_field_name_1=variable_1_to_hold_it<br />
full_swath_data_field_name_n=variable_n_to_hold_it</p>
<p>where the reader supplied already supports these optional swath data field names: scangang, sun_glint_distance, CalFlag, freq, topog, state</p>
<p>The user can add more optional data fields by using the code as an example.</p>
<p></p>
<p></p>
<p><b><a href="/AIRS/documentation/airs_l2/DOCS/read_swath_l1_hsb.pro.pdf">read_swath_l1_hsb.pro.pdf</a></b></p>
<p><b>reads:</b><br />
Level 1B HSB Radiance Product</p>
<p><b>minimal call sequence:</b><br />
read_swath_l1_hsb, pattern, numfp, numline, tai, lat, lon, rad, solzen</p>
<p><b>input:</b><br />
pattern path/filename of AMSU L1B product to be read</p>
<p><b>output</b>:<br />
numfp number of HSB footprints in swath scanline<br />
(usually = <b>GeoXTrack</b> = 90)<br />
numline number of HSB scanlines in swath<br />
(usually = <b>GeoTrack = 135</b>)<br />
tai array of HSB footprint tai ( tai[numfp,numline] ), sec<br />
lat array of HSB footprint latitudes ( lat[numfp, numline] ), deg<br />
lon array of HSB footprint longitudes ( lon[numfp, numline] ), deg<br />
rad array of HSB radiances ( rad[Channel, numfp, numline] ), K<br />
where <b>Channel</b> = 5. The example reader fills this array with<br />
the swath data field named <b>brightness_temp</b><br />
solzen array of HSB footprint solar zenith angles<br />
( solzen[numfp,numline] ), deg</p>
<p><b>expanded call sequence:</b><br />
read_swath_l1_hsb, pattern, numfp, numline, tai, lat, lon, rad, solzen<br />
full_swath_data_field_name_1=variable_1_to_hold_it<br />
full_swath_data_field_name_n=variable_n_to_hold_it</p>
<p>where the reader supplied already supports these optional swath data field names: scangang, sun_glint_distance, satheight</p>
<p>The user can add more optional data fields by using the code as an example.</p>
<p></p>
<p><b><a name="acronyms" id="acronyms">Acronyms</a></b></p>
<table width="549" border="0" cellspacing="2" cellpadding="0">
<tr>
<td><b>ADPUPA </b></td>
<td>Automatic Data Processing Upper Air (radiosonde reports)</td>
</tr>
<tr>
<td><b>AIRS</b></td>
<td>Atmospheric infraRed Sounder</td>
</tr>
<tr>
<td><b>AMSU</b></td>
<td>Advanced Microwave Sounding Unit</td>
</tr>
<tr>
<td><b>DAAC</b> </td>
<td>Distributed Active Archive Center</td>
</tr>
<tr>
<td><b>DN</b></td>
<td>Data Number</td>
</tr>
<tr>
<td><b>ECMWF</b></td>
<td>European Centre for Medium Range Weather Forecasts (UK)</td>
</tr>
<tr>
<td><b>ECS</b></td>
<td>EOSDIS Core System</td>
</tr>
<tr>
<td><b>EDOS</b></td>
<td>Earth Observing System Data and Operations System</td>
</tr>
<tr>
<td><b>EOS</b></td>
<td>Earth Observing System</td>
</tr>
<tr>
<td><b>EOSDIS</b></td>
<td>Earth Observing System Data and Information System</td>
</tr>
<tr>
<td><b>ESDT</b></td>
<td> Earth Science Data Type</td>
</tr>
<tr>
<td><b>EU</b></td>
<td>Engineering Unit</td>
</tr>
<tr>
<td><b>FOV</b></td>
<td>Field of View</td>
</tr>
<tr>
<td><b>GDAAC</b></td>
<td>Goddard Space Flight Center Distributed Active Archive Center</td>
</tr>
<tr>
<td><b>GSFC</b></td>
<td>Goddard Space Flight Center</td>
</tr>
<tr>
<td><b>HDF</b></td>
<td>Hierarchical Data Format</td>
</tr>
<tr>
<td><b>HSB</b> </td>
<td>Humidity Sounder for Brazil</td>
</tr>
<tr>
<td><b>L1A</b></td>
<td>Level 1A Data</td>
</tr>
<tr>
<td><b>L1B</b></td>
<td>Level 1B Data</td>
</tr>
<tr>
<td><b>L2</b></td>
<td>Level 2 Data</td>
</tr>
<tr>
<td><b>L3</b></td>
<td>Level 3 Data</td>
</tr>
<tr>
<td><b>LGID</b></td>
<td>Local Granule IDentification</td>
</tr>
<tr>
<td><b>MW</b></td>
<td>Microwave</td>
</tr>
<tr>
<td><b>NCEP</b></td>
<td>National Centers for Environmental Prediction</td>
</tr>
<tr>
<td><b>NESDIS</b></td>
<td>National Environmental Satellite, Data and Information Service</td>
</tr>
<tr>
<td><b>NIR</b></td>
<td>Near Infrared</td>
</tr>
<tr>
<td><b>NOAA</b></td>
<td>National Oceanic and Atmospheric Administration</td>
</tr>
<tr>
<td><b>PGE</b></td>
<td>Product Generation Executive</td>
</tr>
<tr>
<td><b>PGS</b></td>
<td>Product Generation System</td>
</tr>
<tr>
<td><b>PREPQC</b> </td>
<td>NCEP quality controlled final observation data</td>
</tr>
<tr>
<td><b>QA</b></td>
<td>Quality Assessment</td>
</tr>
<tr>
<td><b>RTA</b></td>
<td>Radiative Transfer Algorithm</td>
</tr>
<tr>
<td><b>SPS</b></td>
<td>Science Processing System</td>
</tr>
<tr>
<td><b>URL</b></td>
<td>Universal Reference Link</td>
</tr>
<tr>
<td><b>VIS</b></td>
<td>Visible</td>
</tr>
<tr>
<td><b>WMO</b></td>
<td> World Meteorological Organization</td>
</tr>
</table>
<p></p>
</div>
</div>
</div>
</div>
</div>
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</tr>
</table>
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