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GES DISC DAAC Data Guide:UARS HRDI Level 3A Data Sets Document

HRDI Instrument

Summary:

The High-Resolution Doppler Imager (HRDI) was one of 10 instruments aboard the Upper Atmosphere Research Satellite (UARS). The instrument was designed to study the dynamics of the Earth's atmosphere. HRDI used to observe the emission and absorption lines of molecular oxygen (and other atmospheric components) in small volumes (4 km in height by 50 km in width) above the limb of the Earth. From the Doppler shift of the lines, the horizontal winds can be determined, while the line shapes and strengths yield information about the temperature and atmospheric species make-up. The goal of the HRDI was to measure atmospheric wind components in the stratosphere, mesosphere, and lower thermosphere. HRDI began collecting useful data in November 1991 and was continued till December 2005. HRDI data have been processed to levels 1, 2, and 3. Currently, HRDI level 3AL and 3AT stratospheric and mesospheric wind data for the complete period (1991-2005) are available from the Goddard Earth Sciences Data and Information Services Center (GES-DISC).

Table of Contents:

1. Data Set Overview

Data Set Identification:

UARS HRDI Level 3AL Daily Latitude ordered data on Altitude Surfaces 

UARS HRDI Level 3AL Daily Latitude ordered data  on Pressure Surfaces

UARS HRDI Level 3AT Daily Time ordered data on Altitude Surfaces

UARS HRDI Level 3AT Daily Time ordered data on Pressure Surfaces

Data Set Introduction:

HRDI data are a subset of the UARS dataset. There are two HRDI level 3A data products archived at the DAAC:

Level 3AL

HRDI level 3AL data are daily latitude-ordered data interpolated to intervals of 4 degrees latitude at the intersection of the tangent track of the instrument's line of sight (LOS). Each record consists of a single array of data of one parameter for a specific time. Level 3AL data records are written to UARS defined standard latitudes, which range from -88 to +88 degrees in 4 degree intervals.

Level 3AT

HRDI level 3AT data are daily time-ordered data, arranged at time intervals of 65.536 seconds, or about 495 km intervals along the LOS tangent track. The reference time at which level 3AT data are arranged is common across all UARS level 3AT files. For both 3AL and 3AT data, each record contains an array of "quality assessment" values with one value corresponding to a profile data value. The data file structures for these data products are in the Standard Formatted Data Units (SFDU) documents listed in the Reference section.

Objective:

The goal of HRDI is to measure wind velocities in the stratosphere, mesosphere, and lower thermosphere during the day with an accuracy of 5 m/s, and also to measure the winds in the mesosphere and lower thermosphere at night. HRDI determines winds by measuring the Doppler shifts of atmospheric absorption and emission features of the molecular oxygen band. Line of sight wind measurements are taken in two directions, forward and backward with respect to the spacecraft direction, thus allowing the wind vector to be formed.

Summary of Parameters:

The primary products of HRDI measurements are vertical profiles of wind (meridional and zonal components) in the stratosphere (10 to 40 km.), and mesosphere/lower thermosphere (50 to 115 km). Secondarily, it is possible to recover temperature, O2 atmospheric band volume emission rate, and O3 and O(1D) mixing ratios in the mesosphere and lower thermosphere, and aerosol and molecular extinction coefficients in the stratosphere.

Discussion:

The HRDI Level 3AL and 3AT data files are written in the Standard Data Format Units (SFDU) format. Each file consists of three records called SFDU, LABEL, and DATA. SFDU and LABEL records contain descriptive information about the instrument and the data, such as start/stop time of the data, number of records in the file, etc. The DATA record contains the profile data and their standard deviations. Time, latitude longitude, local solar time, and solar zenith angles are provided with each DATA record. Each data file is accompanied by a short ASCII metadata file, which provides descriptive information such as the start and stop time of the data, file record lengths, and the UARS quality flag.

Related Data Sets:

The UARS Wind Imaging Interferometer (WINDII) instrument also measures wind and temperature data in the mesosphere and lower thermosphere.

All UARS level 3AL and 3AT files use the same formats to allow for intercomparisons of atmospheric profiles between the different instruments. UARS correlative data products can be used to validate the HRDI data.

2. Investigators:

Principal Investigator:

Name:
Paul B. Hays
Addresses:
University of Michigan
Space Physics Research Laboratory
Department of Atmospheric, Oceanic, and Space Sciences
2455 Hayward Street
Ann Arbor, MI 48109-2143
Telephone Numbers:
+1-313-764-7220 (voice)
+1-313-763-7130 (fax)
Electronic Mail Address:
hays@sprlj.sprl.umich.edu

Title of Investigation:

High Resolution Doppler Imager

Contact Information:

Contact for Scientific Aspects of Data:
Name:
Wilbert R. Skinner
Addresses:
University of Michigan
Space Physics Research Laboratory
Department of Atmospheric, Oceanic, and Space Sciences
2455 Hayward Street
Ann Arbor, MI 48109-2143
Telephone Numbers:
+1-313-647-3960 (voice)
+1-313-763-7130 (fax)
Electronic Mail Address:
wskinner@umich.edu
Contact for Data Generation:
Name:
David A. Gell
Addresses:
University of Michigan
Space Physics Research Laboratory
Department of Atmospheric, Oceanic, and Space Sciences
2455 Hayward Street
Ann Arbor, MI 48109-2143
Telephone Numbers:
+1-313-763-6221 (voice)
+1-313-763-7130 (fax)
Electronic Mail Address:
gellda@umich.edu

3. Theory of Measurements:

HRDI measures winds by determining the Doppler shift of absorption and emission lines in the O2 atmospheric band, mainly looking above the limb of the earth. Emission lines in the (0-0) A band are used to make measurements in the mesosphere and lower thermosphere (MLT), while absorption lines in the B(1-0) and gamma (2-0) are used in the stratosphere. The atmospheric band of O2 is one that is particularly useful for probing the MLT region, since during the day, the entire atmosphere from ~50 to ~110 km emits this band very strongly. Several excitation sources result in a nearly constant brightness over the MLT region.

At night all of these sources disappear except for the weak chemical source near 95 km. This is of sufficient brightness to allow wind measurements at this altitude. Line of sight winds will be taken in two directions, thus allowing the wind vector to be formed.

Secondarily, it is possible to recover temperature, O2 atmospheric band volume emission rate, and O3 and O(1D) mixing ratios in the mesosphere and lower thermosphere, and aerosol and molecular extinction coefficients in the stratosphere. The operating mode of the instrument determines which of the other quantities are measured, and how often a measurement is made.

4. Equipment:

Instrument Description:

Overview:

The HRDI instrument uses a triple-etalon Fabry-Perot interferometer to measure the Doppler shifts of rotational lines of atmospheric molecular oxygen. Typically, the instrument scans the atmosphere at a 45 degree angle to the spacecraft velocity vector, and then points 135 degrees to perform a second scan of the atmosphere. The cycle is then repeated. The same volume of space can be seen from two directions (forward and backward), separated by about 9 minutes. The horizontal wind components can then be calculated from the two line-of-sight (LOS) measurements. HRDI can provide some measurements at night, but only provides full sets of measurements during the daytime.

HRDI collected scientific data from 06 November 1991 to the present.

Collection Environment:

Satellite data are collected from a near-circular Earth orbit of about 585 km altitude and 57 degree inclination.

Platform:

Upper Atmosphere Research Satellite (UARS).

Platform Mission Objectives:

UARS was launched September 12, 1991 with the mission of investigating the chemical and dynamical processes of the Earth's upper atmosphere. See the UARS Project document for more information.

Calibrations

There are four different types of in-flight calibrations:

  1. high frequency calibration checks which are performed every 1-2 days,
  2. low frequency periodic detailed calibrations (approximately every 36 days),
  3. instrument pointing, and
  4. one of a kind or infrequent special calibrations.

5. Data Acquisition Methods:

Data are telemetered from UARS through the Tracking and Data Relay Satellite System (TDRSS) to the Data Capture Facility (DCF) at NASA GSFC. From there the data are given an initial quality check, and are then forwarded to the UARS Central Data Handling Facility (CDHF). The instrument PI teams are connected to the CDHF through remote analysis computers (RACs), where they have developed software to convert the raw data to higher level processed data. The CDHF uses the production software to convert the level 0 (raw) data to level 1, 2, 3A and 3B data. The Goddard DAAC acquires the UARS data from the CDHF.

6. Observations:

Data Notes:

Version 11 files were created using corrections for the long-term drifts of the instrument, and an updated stratospheric aerosol calibration in addition to corrections for other instrumental effects. Version 11 data contain stratospheric wind data as well as mesospheric winds, mesospheric temperatures, and O2 band volume emission rates as well. Future versions of the files will contain mesospheric ozone and O1d mixing ratios and stratospheric aerosol extinction coefficients, in addition to the products available earlier.

7. Data Description:

Spatial Characteristics:

Spatial Coverage:

The HRDI instrument provides coverage of the Earth from -80 to 80 degrees latitude, with the coverage for an individual orbit being at least 35 degrees smaller. Since the HRDI telescope is not fixed to the spacecraft, it can view either side of the spacecraft for a particular orbit (-45 to 80 degrees latitude or 45 to -80 degrees latitude). The system can only provide full altitude coverage when viewing sunlit atmosphere - when viewing the night side of orbits recovered winds are limited to a narrow band near 95 km. Longitude coverage is global. Vertical coverage is from approximately 10 to 115 km.

For HRDI level 3a version 11 mesospheric zonal and meridional winds, the daytime altitude range differs according to modes run and time period. There are three main periods:

  1. Before UARS day 201 (3/29/1992) HRDI provided mesospheric data from two different modes, one of which gave results from 80 to 105 km (strato-meso mode), while the other covered from 65 to 105 km. These two modes were generally alternated on a daily basis during this period with the stratospheric mode, so that during a three day period, there may be 80-105km coverage, no mesospheric coverage, then 65-105 km coverage.
  2. 65 to 105 km between UARS day 201 and UARS day 620 (5/22/1993),
  3. 50 to 115 km after UARS day 620. Please note that some data are available above these altitude ranges, at lower quality.

Nighttime winds are only available at the peak of the O2 Atmospheric (0,0) band, which is approximately 94 km but varies (and is always reported as 96 km in our data).

In the HRDI level 3a products, if there is only a single altitude reported, the data are nighttime winds results.

Spatial Coverage Map:

Data coverage for HRDI looking northward on 5/22/1992.

Map showing UARS orbital tracks

Spatial Resolution:

Level 3AL: 4 degrees latitude, varies in longitude.
Level 3AT: varies in latitude and longitude. Near the equator, latitude resolution is about 3 degrees.

Vertical resolution is 3 to 5 km.

Projection:

Not Applicable.

Grid Description:

HRDI level 3A data have been referenced to both the UARS standard pressure grid (subtype _P), and the UARS standard altitude grid (subtype _A). The index of the data array defines the pressure level in millibars:

        P(i) = 1000 x 10**(-i/6) mb, where i=0,1,2,...

The altitude levels in km are:

  Z(i) = 5 * i,                 i <= 12
  Z(i) = 60 + (i - 12) * 3,     13 <= i <= 32
  Z(i) = 120 + (i - 32) * 5,    33 <= i <= 88

Temporal Characteristics:

Temporal Coverage:

The data covers a period of November 1991 April 2005 for mesospheric winds and 1991-2001 for stratospheric winds. The UARS spacecraft was deactivated on 14 December 2005, completing 78084 orbits over 5208 mission days. Listed below are the dates within the above time period for which HRDI data are missing or erroneous:

1-52       (09/12/1991 thru 11/02/1991)  insufficient instrument control coefficients
85-90      (12/05/1991 thru 12/10/1991)  contain invalid winds
202-226    (03/31/1992 thru 04/24/1992)  contain invalid winds
510-519    (02/02/1993 thru 02/11/1993)  contain invalid winds
583-587    (04/16/1993 thru 04/20/1993)  contain invalid winds
266-313    (06/03/1992 thru 07/20/1992)  No measurements available
694-698    (08/05/1993 thru 08/09/1993)  No measurements available
737-743    (09/17/1993 thru 09/23/1993)  No measurements available
753-775    (10/03/1993 thru 10/25/1993)  No measurements available
1290-1302  (03/24/1995 thru 04/05/1995)  No measurements available

NOTE: Before UARS day 394 (10/09/1992) HRDI made nighttime wind measurements approximately only one day out of three; after day 394 nighttime winds were measured nearly every day.

Until UARS day 900 (02/27/1994) the HRDI instrument alternately measured winds in the mesosphere and stratosphere on a daily basis (one day stratosphere, the next mesosphere), except for several special campaign periods each year. Since UARS day 900 the 'standard' sampling mode has changed to alternating orbits in the stratosphere and mesosphere, so that every day will contain some stratospheric and mesospheric data (again, with the exception of special campaigns). Currently the DAAC supports HRDI stratospheric and mesospheric wind data.

Temporal Resolution:

The temporal resolution of HRDI level 3A data granules is daily.

Data Characteristics:

Parameters:

There are eight1 parameters for each HRDI version 11 Level 3AL and 3AT data product. The parameters are classified according to HRDI subtypes. The measured parameters are listed below with the original HRDI subtype name, DISC parameter name, units, data directory and period of availability:

(i) UARHR3AL  (Latitude ordered data)

 

Parameters

 

Data Directory

Data Period

Meridional winds for Altitude surface  (m/s)

UARHR3ALMERWINA.001

1991-2005

Meridional winds for Pressure surface  (m/s)

UARHR3ALMERWINP.001

1991-2005

Zonal winds for Altitude surfaces    (m/s)

UARHR3ALZONWINA.001

1991-2005

Zonal winds for Pressure surfaces    (m/s)

UARHR3ALZONWINP.001

1991-2005

O singlet d on Altitude surfaces      (ppm)

UARHR3ALO1DA.001

1991-2005

O singlet d on Pressure surfaces      (ppm)

UARHR3ALO1DP.001

1991-2005

O3 on Altitude surfaces                   (ppm)

UARHR3ALO3A.001

1991-2005

O3 on Pressure surfaces                  (ppm)

UARHR3ALO3P.001

1991-2005

Temperature on Altitude surfaces     (°K)

UARHR3ALTEMPA.001

1991-2005

Temperature on Pressure surfaces      (°K)

UARHR3ALTEMPP.001

1991-2005

O2 band volume emission rate on Altitude surfaces (cm-3)

UARHR3ALVOLERA.001

1991-2005

O2 band volume emission rate on Pressure surfaces  (cm-3)

UARHR3ALVOLERP.001

1991-2005

 

 

(ii) UARHR3AT  (Time referenced data)

Parameters

 

Data Directory

Data Period

Meridional winds for Altitude surface  (m/s)

UARHR3ATMERWINA.001

1991-2001

Meridional winds for Pressure surface  (m/s)

UARHR3ATMERWINP.001

1991-2001

Zonal winds for Altitude surfaces         (m/s)

UARHR3ATZONWINA.001

1991-2001

Zonal winds for Pressure surfaces         (m/s)

UARHR3ATZONWINP.001

1991-2001

O singlet d on Altitude surfaces            (ppm)

UARHR3ATO1DA.001

1991-2001

O singlet d on Pressure surfaces           (ppm)

UARHR3ATO1DP.001

1991-2001

O3 on Altitude surfaces                        (ppm)

UARHR3ATO3A.001

1991-2001

O3 on Pressure surfaces                        (ppm)

UARHR3ATO3P.001

1991-2001

Temperature on Altitude surfaces         (°K)

UARHR3ATTEMPA.001

1991-2001

Temperature on Pressure surfaces        (°K)

UARHR3ATTEMPP.001

1991-2001

O2 band volume emission rate on Altitude surfaces (cm-3)

UARHR3ATVOLERA.001

1991-2001

O2 band volume emission rate on Pressure surfaces (cm-3)

UARHR3ATVOLERP.001

1991-2001

 

 

 

(Data Granularity:

 

The granularity of HRDI data is defined such that there is one granule for each process level (3AL and 3AT), and parameter subtype (see the Parameters section above) per day, for a total of 16 granules per day. Each HRDI Level 3A data granule is a multi-file granule consisting of two files:

  1. The binary data file (files ending with PROD, or *PROD extension) which contains the vertical profile data, along with quality indicators, time, latitude, longitude, local solar time, and solar zenith angle.

     

  2. An ASCII metadata file (files ending with META, or *META extension) associated with the data file containing items such as the begin date, end date, PI assigned quality flag and record length size of the data file.

The naming convention for UARS granule file names distributed by the Goddard DAAC is as follows:

HRDI_Llll_Sssss_Ddddd .Vvvvv_Ccc_xxxx,

where:

lll
is the UARS processing level (3AL or 3AT),
ssss
is the subtype or parameter),
dddd
is the UARS acquisition day (0001 = 12 September 1991),
vvvv
is the data version number),
cc
is the data version cycle number, and
xxxx
is the file extension (PROD for the binary files, or META for the ASCII metadata files)

For a full description of the naming convention see the "meta_desc.doc" file.

Average granule size for 3AT altitude gridded (_A) products is about 280 KB. For 3AT pressure gridded (_P)products, the average granule size is 170 KB. The average granule size for 3AL altitude gridded (_A) products is about 195 KB. For 3AL pressure gridded (_P) products, the average granule size is 125 KB. The *META files are small, only about 7 00 bytes each.

Data Format:

The data are in a native UARS format (SFDU). The files were originally created on a VAX/VMS system at the UARS CDHF, and now exist as UNIX stream files at the Goddard DAAC. WINDII data file structures are presented in the Standard Formatted Data Units (SFDU) documents listed in the References section.

9. Data Manipulations:

Formulae:

Derivation Techniques and Algorithms:

After a scan of data has been accumulated, the data are analyzed by first finding the average signal in each channel. The signal is corrected for instrument dead time, the dark counts (background value) are subtracted from the data, the signal level for each channel is converted to Rayleighs per inverse centimeter, and the line of sight velocity of the atmosphere is calculated using the Doppler shift of an atmospheric absorption or emission

Data Processing Sequence:

Processing Steps:

In the Level 3 data processing software, each profile is read sequentially from the Level 2B source file, and the location, time and data type (i.e., which region of the atmosphere does the profiles contain data for, and what geophysical data does it contain) are stored. The sequence of profiles of each type is divided into subsequences called 'semi-orbits'. The HRDI Level 3 processing analyzes all data (for each atmospheric region and data type) for one semi-orbit at the same time, pairing profiles for different regions (so a single profile can represent both mesospheric and stratospheric data), filling points on the standard latitude grid by interpolation, pairing forward- and backward-looking velocity scans to determine wind velocity components, and pairing pressure profiles to all other types so that data can be written onto a pressure grid rather than the altitude gridding that Level 2B uses. The data are then interpolated onto a time grid, using the latitude gridded profiles if the profiles are obtained by pairing, otherwise by simply interpolating between consecutive profiles onto the time grid point between.

Processing Changes:

Reprocessing of the data occur about once a year.

Calculations:

Special Corrections/Adjustments:

None.

Calculated Variables:

The retrieval of parameters is based on a sequential estimation algorithm. Other values, such as latitude, longitude, local solar time, and solar zenith angles are retrieved from routines at the UARS CDHF, and included with each data record in the data files.

10. Errors:

Sources of Error:

Systematic effects with the level 3A data result from the sequential estimation routine, in effect taking a weighted average of the current measurement and those near it in time and location. As a result small scale features in the real winds may be smoothed out by this process. No sequential estimation is used in determining the nighttime winds.

Quality Assessment:

Data Validation by Source:

All data are checked by the HRDI science team and assigned quality values. These values appear as the DATA_QUALITY_UARS fields in the ASCII metadata files. The format for DATA_QUALITY_UARS is a 3 character field of the form "p.q" where:

                VALUE       MEANING
         for p      0       Machine inspected
                    1       Qualitative evaluation
                    2       Intensive analysis
         for q      1       less than 50% good data
                    2       50% - 75% good data
                    3       76% - 98% good data
                    4       better than 98% good data

For HRDI, the DATA_QUALITY_PI field is filled with the same value as DATA_QUALITY_UARS. The DATA_QUALITY_UARS field is also displayed in the IMS's Inventory Details screen under the Additional Information section for each data granule.

Measurement Error for Parameters:

Precision information is available in the 'data quality' field of the file, which contains the standard deviations of the measurements. These values depend on viewing conditions, at 95 km with low solar zenith angle, they can be less than 3 m/s, while under 'average' conditions (solar zenith angle about 30 degrees) the standard deviation of the data varies from 6 to 12 m/s at 111 km, from 3 to 7 m/s at 95 km, from 8 to 15 m/s at 69 km, and from 20 to 40 m/s at 50 km.

Additional Quality Assessments:

The accuracy of the data set depends on how well the 'zero wind' position has been determined for the current mode of instrument operation. The 'zero wind' position has been determined to within 5 m/s, for most data before UARS day 1000 (06/07/1994), and 10 to 15 m/s after UARS day 1000. These later data have not yet been fully validated.

Also, there are some days (before UARS day 201, 06/30/1992) during which different modes were run which, because of the small size of the data set, cannot be validated/calibrated to the same degree as the rest of the data set. These are UARS days: 63-79 (11/13/1991 thru 11/29/1991), 113-120 (01/02/1992 thru 01/09/1992), 134-149 (01/23/1992 thru 02/07/1992), 165-173 (02/23/1992 thru 03/02/1992), 182-189 (03/11/1992 thru 03/18/1992). The accuracy of these data is at or near the 10 m/s level.

The user is referred to the HRDI Data Quality and Usage document for any problems with the data.

Data Verification by Data Center:

Data files are checked to ensure that they are properly transferred and translated from their original VAX/VMS format at the UARS CDHF to the DAAC's UNIX format. No additional data checks are performed by the DAAC.

11. Notes:

Limitations of the Data:

The data files exist as UNIX stream files at the DAAC. Binary data are IEEE formatted. The binary data files should be read on 32 bit machines running UNIX operating systems. This is especially important for fields which are IEEE floating point values, such as the profile data and quality values. If you are going to use a non 32-bit and/or non-UNIX machine, then you will need to write your own conversion routines to read the data files.

File record length information is only listed in the ASCII metadata files (*META extension) which accompany the data and parameter files.

The CDHF contains several versions of processing results for each day of data - no HRDI data earlier than version 7 should be used for scientific study. Version 7 data files include only mesospheric winds (daytime and nighttime). Version 8 files differ from version 7 files only in that they fix a problem in the version 7 files for days on and after 02/12/1993 (UARS day 520 - days since the spacecraft was activated). Version 9 files contain stratospheric wind data as well as mesospheric winds. Version 10 files differ from the prior version only in that they were created using updated corrections for the long-term drifts of the instrument, and an updated stratospheric aerosol calibration. Version 11 files were created using further corrections for the instrumental effects, and contain mesospheric temperatures, O2 band volume emission rates as well. Future versions of the files will contain mesospheric ozone and O1d mixing ratios and stratospheric aerosol extinction coefficients, in addition to the products available earlier.

Known Problems with the Data:

The HRDI instrument has been collecting scientific data since November 2, 1991. There have been several periods when the instrument was either off or not in a condition to make useful measurements. These are summarized in Table 1. There have been two occasions when there have been hardware problems that have temporarily prevented scientific data collection. Fortunately, both had work-arounds that allowed complete recovery.

HRDI TIMELINE
Date UARS Operational Day Description
Sep 12, 1991 1 UARS launch
Oct 1, 1991 20 HRDI activation
Nov 2, 1991 52 Scientific observations began
Mar 30-Apr 26, 1992 201-228 Instrument data of limited value due to MRE post 2 partial failure
Jun 2-Jul 22, 1992 265-301 Instrument off due to spacecraft solar array problem
Feb 2-12, 1993 510-520 Instrument data of limited value due to MRE post 1 partial failure
Feb 15, 1993 523 Calibrations performed on night side only
Jun 14, 1993 642 Begin temperature feedback
Aug 2, 1993 691 Improved yaw offset calibration
Aug 2, 1993 691 Begin improved temperature feedback
Aug 4-9, 1993 694-698 Instrument off due to spacecraft solar array problem
Sep 17-23, 1993 737-743 Instrument off due to spacecraft solar array problem
Oct 2-7, 1993 752-757 Instrument off due to spacecraft solar array problem
Oct 22-26,1993 772-776 Instrument off due to spacecraft solar array problem
Dec 8-9, 1993 819-820 Instrument off due to low battery power
Mar 15, 1994 916 Reduced calibration frequency began
Mar 24-Apr 6, 1995 1290-1303 Instrument off due to spacecraft solar array problem
Apr 17, 1995 to ? 1314-? Instrument off due to spacecraft solar array problem

The HRDI instrument has had two hardware failures, and has also been somewhat affected by the UARS spacecraft solar array problems, and HRDI's exposure to the space environment. Please see the HRDI Data Quality and Usage document for a description of these problems.

Usage Guidance:

HRDI level 3A data are interpolated to create both L3AT and L3AL data files. They are also available on both an altitude and pressure grid. The HRDI team recommends using the altitude gridded data for a number of reasons: 1) the HRDI instrument makes its measurements on the altitude grid, 2) the pressure gridded data are produced using NMC pressure/altitude data for the given day, a somewhat smoothed product, and 3) the UARS standard grid for pressure has a top level of 1.47e-3 mb, or about 90 km, while HRDI makes measurements well above this level.

 

Any other Relevant Information about the Study:

None.

12. Application of the Data Set:

These data are intended for those interested in studying atmospheric dynamics and winds in the stratosphere and mesosphere. Knowledge of the stratospheric wind field will help to determine how transport and mixing influence the ozone budget in the lower stratosphere, and to quantify the mean and eddy circulations associated with the observed semiannual oscillations. In the mesosphere, the wind measurements will contribute to the understanding of the relative role of turbulent diffusion and bulk advection in accounting for mesospheric tracer budgets.

13. Future Modifications and Plans:

The HRDI data will be reprocessed to a new data version if problems are discovered with the current data, or if a better algorithm is developed in the future. Users who have previously ordered these data will be notified by e-mail on the availability of any reprocessed data.

The following data products are planned for future development: O3 mixing ratio 1e-4 to 1e-8, O(1D) mixing ratio 1e-11 to 1e-14, molecular and aerosol extinction coefficients 0 to .5.

 

14. Read Software:

Software Description:

Simple read/dump programs are available for reading the HRDI level 3A data files. The read programs are available in C and IDL languages.
 

Software Access:

To get the software use the links below:
 

15. Data Access:

Contacts Information:

Name:
Help Desk
Addresses:
NASA Goddard Space Flight Center
Code 610.2
Greenbelt, MD 20771
Telephone Numbers:
Phone: 1-301-614-5224
FAX: 1-301-614-5268
Electronic Mail Address:
gsfc-help-disc@lists.nasa.gov

 

Archive Identification:

The UARS HRDI data are archived at the GES DISC under the UARS Project.

Procedures for Obtaining Data:

The HRDI level 3A data files can be obtained from the GES DISC by several mechanisms. These include the following:

 

Data Archive Status/Plans:

The GES DISC currently supports HRDI level 3A data products.

16. Output Products and Availability:

The HRDI level 3A data are available. See the section above on Procedures for Obtaining Data for specific information. For more information on HRDI, please refer to the HRDI Home Page.

17. References:

Satellite/Instrument/Data Processing Documentation:

'The Upper Atmosphere Research Satellite (UARS) Mission', Reber, C. A., C. E. Trevathan, R. J. McNeal, and M. R. Luther, J. Geophys. Res. 98, D6, 10643-10647, 1993.

'The High-Resolution Doppler Imager on the Upper Atmosphere Research Satellite', Hays, P. B., V. J. Abreu, M. E. Dobbs, D. A. Gell, H. J. Grassl, and W. R. Skinner, J. Geophys. Res. 98, D6, 10713-10723, 1993.

Journal Articles and Study Reports:

'Remote Sensing of Mesospheric Winds with the High Resolution Doppler Imager' Hays, P. B., et al., Planet. Space Sci., 40, 1599-1606, 1992.

'Global Mesospheric Tidal Winds Observed by the High Resolution Doppler Imager on Board the Upper Atmosphere Research Satellite', Morton, Y. T., R. S. Lieberman, P. B. Hays, D. A. Ortland, A. R. Marshall, D. Wu, W. R. Skinner, M. D. Burrage, and D. A. Gell, Geophys. Res. Letts., in press, 1993.

'The High Resolution Doppler Imager', Paul B. Hays, Wilbert R. Skinner, Vincent J. Abreu, and Jeng-Hwa Yee, Digest of the Topical Meeting on Optical Remote Sensing of the Atmosphere, 1990, (Optical Society of America, Washington, D. C. 1990), Vol. 4, p. 7.

'A Sequential Estimation Technique for Recovering Atmospheric Data from Orbiting Satellites', D. A. Ortland, P. B. Hays, W. R. Skinner, M. D. Burrage, A. R. Marshall, and D. A. Gell, The Upper Mesosphere and Lower Thermosphere, Geophyiscal Monograph Series, Vol 87, edited by R. Johnson and T. Killeen, AGU, Washington, D. C., 1995.

'Validation of HRDI Mesospheric and Lower Thermospheric Winds', M. D. Burrage, W. R. Skinner, A. R. Marshall, P. B. Hays, R. S. Lieberman, S. J. Franke, D. A. Gell, D. A. Ortland, F. J. Schmidlin, R. A. Vincent, and D. L. Wu, J. Geophys. Res., in press 1996.

'Comparison of HRDI wind measurements with radar and rocket observations', M. D. Burrage, W. R. Skinner, A. R. Marshall, P. B. Hays, R. S. Lieberman, D. A. Gell, D. A. Ortland, Y. T. Morton, D. L. Wu, S. J. Franke, F. J. Schmidlin, and R. A. Vincent, Geophys. Res. Letts. 20, 1259-1263, 1993.

Goddard DAAC IMS online documentation:

HRDI level 3AL SFDU Version 11, NURSHR03.

HRDI level 3AT SFDU Version 11, NURSHR04.

HRDI Data Quality and Usage.

Horne, C., UARS Granule Level File (*META) Description, July 1994.

18. Glossary of Terms:

DATA PRODUCT
A collection of parameters packaged with associated ancillary and labeling data. Uniformly processed and formatted. Typically uniform temporal and spatial resolution. HRDI level 3A data products include HRDI_L3AL_DAILY and HRDI_L3AT_DAILY. The HRDI data product class is divided into data product subclasses according to measured parameters.

 

DATA SET
A logically meaningful grouping or collection of similar or related data. Data having mostly similar characteristics (source or class of source, processing level and algorithms, etc.) HRDI is a subset of the UARS data set.

 

GRANULE
A Granule is the smallest aggregation of data which is independently managed.

 

PARAMETER
A measurable or derived variable represented by the data (e.g. air temperature, snow depth, relative humidity). At the Goddard DAAC, parameters are grouped into a Parameter General category, which is broken down into Parameter Specific.

19. List of Acronyms:

CDHF Central Data Handling Facility
DAAC Distributed Active Archive Center
DCF Data Capture Facility
EOS Earth Observing System
FOV field of view
GSFC Goddard Space Flight Center
HRDI High-Resolution Doppler Imager
IMS Information Management System
JPL Jet Propulsion Laboratory
km kilometer
LOS line of sight
m meter
mb millibar
NASA National Aeronautics and Space Administration
NMC National Meteorological Center
O2 (molecular) oxygen
PI Principal Investigator
RAC Remote Analysis Computer
s second
SFDU Standard Formatted Data Units
TDRSS Tracking and Data Relay Satellite System
UARS Upper Atmosphere Research Satellite
USO User Services Office

20. Document Information:

Document Revision Date:Fri May 10 11:53:48 EDT 2002

23 February 1998

Document Review Date:

Document ID:

Citation:

Document Curator:

Document URL:

/guides/GSFC/guide/uars_hrdi_l3a_dataset.gd.shtml

UARS Home Page UARS Project

Change History

Version 2.0
Version baselined on addition to the GES Controlled Documents List, February 23, 1998.
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