LEGACY DATA: TOVS PATHFINDER PATH A DATASET GUIDE

The TIROS Operational Vertical Sounder (TOVS) Pathfinder Path A dataset contains atmospheric profiles (primarily temperature and humidity) and surface and cloud parameters derived using one of three conceptually distinct algorithms identified by the TOVS Science Working Group (SWG) in November 1991. The purpose of the Pathfinder Project is to make research-quality global change data sets easily available to the science community in support of the US Global Change Research Program (USGCRP) using long term space-based radiance measurements. The initial set of level 3 geophysical products have been derived for the Pathfinder benchmark period from April 1987 through November 1988.

This dataset contains the TIROS Operational Vertical Sounder (TOVS) level 3 geophysical parameters derived using the physical retrieval method of Susskind et al 1984) and processed by the Satellite Data Utilization Office of the Goddard Laboratory for Atmospheres at NASA/GSFC. This method, which is hydrodynamic model- and a priori data-dependent, is designated asthe so-called Path A scheme by the TOVS Pathfinder Science Working Group. The 20 channel High resolution Infrared Radiation Sounder 2 (HIRS2) and the 4 channel Microwave Sounding Unit (MSU) aboard the NOAA-xx series of Polar Orbiting Satellites are used to produce global fields of the three dimensional temperature-moisture structure of the atmosphere. TOVS data is also used to derive surface skin temperature, sea surface temperature, outgoinglongwave radiation, cloud fraction, cloudtop height, total ozone overburden and precipitation estimates. These geophysical parameters are mapped to a 1 degree by 1 degree latitude-longitude grid at 3 different temporal resolutions: daily, 5 day and monthly, separately for the AM and PM periods.

The primary goal of Pathfinder is the production of consistently processed, long term datasets for use in global change studies. TOVS Pathfinder is one of several Pathfinder studies initiated by NOAA and NASA, the others being the AVHRR, GOES, and SSM/I Pathfinders. As a first step in the processing, a common benchmark period was selected to facilitate the analysis and intercomparison of geophysical fields derived from the various Pathfinders. The benchmark period covers the time period April, 1987 through November, 1988. Once the products from the benchmark period have been endorsed by the scientific community, the processing of the long-term dataset will commence using a fixed algorithm. The experience gained from the processing of these large datasets will serve to guide the EOSDIS (Earth Observing System Data and Information System) development effort in support of the next generation of remote sensing platforms to be launched in the late 1990's.

3-dimensional temperature-moisture structure of the atmosphere

Surface properties (surface skin temperature, sea surface temperature)

Physical cloud properties (cloud fraction, cloudtop height, cloudtop temperature, precipitation)

Radiation Budget (outgoing longwave radiation, cloud radiative forcing)

All of the following material has been extracted from the instrument references given in section 15.1.

The overall mission of the TOVS instruments aboard the NOAA Polar Orbiting Environmental Satellites (POES) is to provide continuous, global measurements of atmospheric temperature and moisture profiles. These profiles are then used to initialize numerical general circulation models for improved, operational weather forecasting capabilities.

atmospheric emission in seven 15.3 micron CO2 channels
atmospheric emission in five 4.3 micron CO2 channels
surface and H2O emission in one 11.0 micron window channel
surface and O3 emission in one 9.6 micron window channel
atmospheric emission in five 6.7 micron H2O channels
surface emission & reflected solar radiation in two 3.7 micron window channels

Microwave Sounding Unit (MSU)

atmospheric emission in three 56 GHz O2 channels
surface emission in one 56 GHz window channel

Stratospheric Sounding Unit (SSU)

upper atmospheric emission in three pressure modulated CO2 channels

HIRS/2: The HIRS/2 instrument measures radiation emitted by the earth-atmosphere system in 19 regions of the infrared spectrum between 3.7 and 15 microns. A visible channel is also available to measure the albedo of the earth's surface. The central wave numbers of these channels are :

          1)   667.70 cm-1              11)  1363.32 cm-1
          2)   680.23                   12)  1489.42
          3)   691.15                   13)  2191.38
          4)   704.33                   14)  2208.74
          5)   716.30                   15)  2237.49
          6)   733.13                   16)  2269.09
          7)   750.72                   17)  2360.00
          8)   899.50                   18)  2514.58
          9)  1029.01                   19)  2665.38
         10)  1224.07                   20) 14453.14

MSU: The MSU instrument is a 4 channel Dicke radiometer making passive microwave radiation measurements in 4 regions of the 50 GHz oxygen emission spectrum. The central frequencies of these channels are:

         1)   50.30 GHz              3)   54.96 GHz
         2)   53.74 GHz              4)   57.05 GHz

The channel bandwidths are 200 MHz in each case, with a typical Noise Equivalent Differential Temperature (NEDT) of 0.3 degrees K. The instrument has two 4 inch scanning reflector antenna systems, orthomode transducers, four Dicke superheterodyne receivers, a data programmer and power supplies. The antennas are step scanned through eleven individual 1.84 second earth-viewing steps and require a total of 25.6 seconds to complete. The MSU data output represents an apparent brightness temperature after a 1.84 second integration period per step. The data is quantized to 12 bit precision and combined with telemetry and step position information to produce an effective output rate of 320 bits per second.

SSU: The SSU employs the technique of pressure modulation to measure radiation emitted by carbon dioxide in the region from 1 to 20 mb. A cell of CO2 gas in the instrument's optical path has its pressure changed in a cyclic manner. The spectral characteristics of the channel and therefore the height of the weighting function is determined by the pressure in the cell during the integration period. By using 3 cells at different pressures, weighting functions peaking at 3 different heights can be obtained. The instrument is step-scanned perpendicular to the subpoint track, and is composed of 8 individual 4 second steps implying a total of 32 seconds per scan. The integrated output signal level is sampled 8 times during each step, and the output is then digitized to 12 bit precision.

The instrument measurement geometry for the TOVS sensors are summarized in the following table:

Instrument parameter         HIRS/2          MSU            SSU
--------------------         ------         ------         ------
Cross track scan angle
(+/- degrees from nadir)      49.5           47.4           40.0
Number of steps                56             11              8
Angular FOV (degrees)         1.25            7.5           10.0
Step Angle (degrees)          1.80            9.5           10.0
Ground IFOV (km)
  - at nadir                  17.4          109.3          147.3
  - at end of scan           59 x 30      323 x 179      244 x 186
Swath width (+/- km)          1120           1174            737

Manufacturer of Instrument:

HIRS/2: Aerospace/Optical Division of ITT
MSU: Jet Propulsion Laboratory
SSU: MSDS, Frimley

Prelaunch calibration of the infrared and microwave channels are carried out by the instrument manufacturers to characterize their performance. The radiometer sequentially views the warm calibrated laboratory blackbody (representing the earth), a blackbody colled to about 77 degrees K (representing the space view), and it's own internal blackbodies. Temperatures of all blackbodies are sensed with thermistors or platinum resistance thermometers (PRTs). Data are collected as the laboratory blackbody is cycled through a sequence of temperature plateaus between 175 and 320 degrees K. This entire procedure is repeated for several instrument operating temperatures to simulate in-orbit variations in instrument temperature. Because of both short- and long-term variations in instrument sensitivity during its period of operation, the radiometers have been designed to view cold space and one or more internal warm blackbodies as part of the normal scan sequence in orbit. Using this information, the signal-to-noise and radiometric calibration coefficients can be monitored during the instrument's lifetime. See Frequency of Calibration for further information regarding in-flight calibration procedures.

Tolerance

Future Entry.

Frequency of Calibration:

HIRS/2: During normal operations, calibration of the HIRS/2 instrument is performed once every 256 seconds (every 40 scan lines). In calibration mode, the mirror rapidly slews to a space view and samples all channels for the equivalent time of of one complete scan. The mirror is then moved to a position where it views a cold calibration target for the equivalent of a full scan. Finally, the mirror is stepped to view the internal warm target for an equivalent amount of time. With these measurements and an accurate determination of the warm and cold body temperatures using PRTs, calibration coefficients up to second order are obtained for that calibration sequence. These are then used with ensuing earth-view digital counts to obtain the corresponding radiances for each HIRS/2 channel.

MSU: The MSU has no special calibration sequence that interrupts normal scanning. The calibration data is included in a scan line of data. From the last earth-view position, the reflector moves 4 steps to view space, then another 10 steps to view the internal blackbody, before beginning a new scan line. Using these measurements, calibration coefficients up to first order are determined for the scan line.

SSU: A calibration sequence is initiated every 256 seconds (equivalent to 8 scans) during which the radiometer is stepped to a position to view cold space, then to an internal blackbody at a know temperature. Using these measurements, calibration coefficients up to first order are determined for that calibration sequence. These are then used with ensuing earth-view digital counts to obtain the corresponding radiances for each SSU channel.

Other Calibration Information:

HIRS/2: No correction for non-linear instrument response is required for the HIRS/2 raw data prior to applying the radiometric calibration coefficients. To convert channel radiances to brightness temperatures, the inverse Planck function is used to obtain an "apparent" brightness temperature, which is adjusted using satellite-specific band correction coefficients. See the Polar Orbiter User's guide for more detailed information.

MSU: A correction for non-linear instrument response is required for the MSU raw data prior to applying the radiometric calibration coefficients. A set of four coefficients is applied to the raw counts using a third order "normalization" equation. The inverse Planck function is used to convert the resulting channel radiances to brightness temperatures.

SSU: No correction for non-linear instrument response is required for the SSU raw data prior to applying the radiometric calibration coefficients. The inverse Planck function is used to convert the resulting channel radiances to brightness temperatures.

There are 360 cells in the longitude direction with the first grid cell centered at 179.5W (near the date line), and with a grid spacing of 1 degree. There are 180 cells in the latitude direction with the first grid cell centered at 79.5S (near the South Pole), and with a grid spacing of 1 degree. The vertical levels coincide with mandatory pressure levels in the case of the temperature and humidity profiles.

Each level 2 spot retrieval is assigned to a single gridbox according to which gridbox the spatial coordinates of the center of the level 2 FOV falls within. For individual gridboxes with multiple observations, a simple unweighted average of all points within the box is used when determining the value of the geophysical parameter to assign to that gridbox. No interpolation or data filling is used for gridboxes with missing data; the fill value for missing or suspect data is contained in the metadata file descriptor annotation accompanying each HDF file. Currently, this value is set to -999.99 for the mean and standard deviation arrays, and 0 for the count arrays.

The level 3 gridded products are created at 3 temporal resolutions: daily, 5 day and monthly. These products are created separately for the AM (descending nodes on morning satellites) and PM (ascending nodes for morning satellites) periods.

Temperature Parameters: Atmospheric temperatures are given at up to 12 pressure levels, including the surface. The surface air temperature is always given. If the model forecast surface pressure is less than a given pressure, the retrieved value for that pressure is given a fill value (-999.99). Average coarse layer temperatures are also derived between four sets of pressure levels.

Water Vapor Profiles: Water vapor profiles are given in terms of specific humidity at 5 mandatory pressure levels. In addition, total precipitable water above the surface and above 4 mandatory pressure levels are also derived and output as additional measures of atmospheric moisture. As in the case of temperature, a fill value (-999.99) is given at mandatory levels if the surface pressure is less than the mandatory level pressure level.

Total Ozone Index: The total ozone index is computed as an experimental parameter using HIRS/2 channel 9 (9.6 microns). The TOMS total ozone is used for tuning the TOVS ozone index on both a latitudinal and seasonal basis. However, unlike TOMS, both daytime and nighttime estimates of the total ozone are obtained using the HIRS/2 measurements.

Surface Parameters: Two surface parameters are provided, namely, the retrieved surface skin temperature (both land and sea) and forecast surface air pressure. The first quantity is derived from the TOVS radiances, and the second is generated by the General Circulation Model.

Cloud Parameters: Ten cloud parameters are derived. These are total effective cloud fraction (for clouds in any layer), effective cloud fraction for clouds with cloud top pressure levels situated in each of seven ISSCP layers, cloud top pressure and cloud top temperature. The cloud top pressure and cloud top temperature are those associated with the total effective cloud fraction. The sum of the cloud fraction in each of the seven layers is equal to the total cloud fraction.

Longwave Radiation Parameters: Longwave radiation parameters are computed from the retrieved cloud parameters and other geophysical parameters. Two quantities are written out: Outgoing Longwave Radiation, defined as the upward longwave flux exiting the top of the atmosphere, and Longwave Cloud Radiative Forcing, defined as the difference between the cloudy sky and clear sky Outgoing Longwave Radiation values.

Precipitation Estimate: The precipitation estimate is an experimental quantity inferred from retrievals of cloud parameters and the relative humidity profile. It is derived over both land and water surfaces.

Other Parameters: There are three other parameters written out in each file. The most important is a quality flag which indicates the degree to which the radiances computed from the retrieval match the observations. The highest quality indicator is 0 and the lowest is 4. By definition, differences between observed and computed radiances for all retrievals included in the data set matched sufficiently closely to be accepted. In addition, the effective HIRS2 observed zenith angle (zenith angles to the right and left of nadir have different signs) and the average local time of day in hours (between 0 and 23.99) are provided to facilitate the interpretation of the retrieval products. The effective zenith angle is defined as the arc-cosine of the average value of the cosines of the individual satellite zenith angles.


Variable	Units		Description
---------	----		------------
TEMPSFC		K	Temperature at surface air 
TEMP1000	K	Temperature at 1000 mb 
TEMP850		K	Temperature at 850 mb 
TEMP700		K	Temperature at 700 mb 
TEMP500		K	Temperature at 500 mb 
TEMP400		K	Temperature at 400 mb 
TEMP300		K	Temperature at 300 mb 
TEMP200		K	Temperature at 200 mb 
TEMP100		K	Temperature at 100 mb 
TEMP70		K	Temperature at 70 mb 
TEMP50		K	Temperature at 50 mb 
TEMP30		K	Temperature at 30 mb 
TEMPGRD     K   Surface Skin Temperature
CLTEMP1		K	Mean temperature surface to 500 mb 
CLTEMP2		K	Mean temperature 500 mb to 300 mb 
CLTEMP3		K	Mean temperature 300 mb to 100 mb 
CLTEMP4		K	Mean temperature 100 mb to 30 mb 
PRWATSFC	cm	Precipitable water vapor above surface 
PRWAT850	cm	Precipitable water vapor above 850 mb 
PRWAT700	cm	Precipitable water vapor above 700 mb 
PRWAT500	cm	Precipitable water vapor above 500 mb 
PRWAT300	cm	Precipitable water vapor above 300 mb
FCLD *		%	Total cloud fraction 
FCLDP1 *	-	Cloud fraction above 180 mb
FCLDP2 *	-	Cloud fraction between 310 and 180 mb
FCLDP3 *	-	Cloud fraction between 440 and 310 mb
FCLDP4 *	-	Cloud fraction between 560 and 440 mb
FCLDP5 *	-	Cloud fraction between 680 and 560 mb
FCLDP6 *	-	Cloud fraction between 800 and 680 mb
FCLDP7 *	-	Cloud fraction below 800 mb
PCLD *		mb	Cloud top pressure for FCLDTOT
TCLD *		K	Cloud top temperature for FCLDTOT 
ZANGLE		deg	HIRS/2 satellite zenith angle 
TIME		hrs	Local time of the day 
QFLAG		N/A	Quality flag (0 is best, 4 is marginal) 
TOZ *		D.U.	Total ozone index 
OLR		W/m^2	Outgoing longwave radiation
LCRF		W/m^2	Longwave cloud radiative forcing 
PRECIP *	mm/day	Precipitation estimate 
SPHUM1000	g/kg	Specific humidity at 1000 mb 
SPHUM850	g/kg	Specific humidity at  850 mb 
SPHUM700	g/kg	Specific humidity at  700 mb 
SPHUM500	g/kg	Specific humidity at  500 mb 
SPHUM300	g/kg	Specific humidity at  300 mb
PSURF       mb      Forecast Surface Pressure

The '*' indicates that these derived parameters were designated as experimental by the TOVS Implementation Team, pending further validation of the results.

The TOVS Path A methodology makes use of a combination of HIRS/2 and/or MSU channel radiances to infer information pertaining to the following groups of geophysical parameters :

Temp profile      H2O profile       Clouds       Surf temp
------------      -----------     -----------    ---------
HIRS....1,2,4     HIRS....8,10    HIRS....4,5    HIRS...8,18,19
     13,14,15            11,12          6,7,8
MSU.......3,4

Cloud Clearing       Ozone
--------------     ---------
HIRS.....13,14     HIRS....9
MSU..........2

where the HIRS/ and MSU channel designations are listed in section 5.1.5 of this document.

The TOVS Pathfinder level 3 output consist of binary files containing 2- and 3-dimensional geophysical parameters mapped to a rectangular latitude-longitude grid. For each parameter, each cell in the grid is characterized by a mean value of that parameter, the associated standard deviation, and the number of observations used in computing the first two quantities. All 3 of these statistics are stored as Scientific Data Sets (SDSs) in the Hierarchical Data Format (HDF). Means and standard deviations are stored as 32 bit floating point words, while the number of observations in each gridbox or the " gridbox counts" are represented as 16 bit integers. Version 3.2 release 4 of HDF (HDF3.2r4) was used to create all level 3 files The overall structure of a TOVS HDF file is shown in the schematic below:

SDS   SDS Name    SDS Dims     SDS Description
----  ---------   ---------    ---------------
 1    TEMP        360x180x12   Vertical temperature profile at 12 levels
 2    CLTEMP      360x180x4    Mean temperatures for 4 coarse layers
 3    PRWAT       360x180x5    Total precipitable water above 5 levels
 4    TSURF       360x180      Surface skin temperature
 5    FCLD        360x180      Effective total cloud fraction
 6    FCLDP       360x180x7    Effective cloud fraction, 7 ISSCP layers
 7    PCLD        360x180      Effective cloudtop pressure
 8    TCLD        360x180      Effective cloudtop temperature
 9    ZANGLE      360x180      Effective satellite zenith angle
10    TIME        360x180      Time of day
11    QFLAG       360x180      Quality flag
12    TOZ         360x180      Total ozone index
13    OLR         360x180      Outgoing longwave radiation
14    LCRF        360x180      Longwave cloud radiative forcing
15    PRECIP      360x180      Precipitation estimate
16    SPHUM       360x180x5    Specific humidity profile at 5 levels
17    PSURF       360x180      Model forecast surface pressure

The fundamental formulae used in the TOVS Path A methodology can be found in a postscript file in the anonymous ftp directory /pub/tovs/pathA/doc/appendixAB.ps located on eosdata.gsfc.nasa.gov.

There have been many improvements to the old retrieval system, described in Susskind and Pfaendtner (1989), arising from research we have been doing and incorporated in the Pathfinder processing scheme. These include :

coupling the interactive retrieval system with a new higher vertical resolution General Circulation Model and Optimal Interpolation Analysis scheme
developing an improved iterative scheme for both temperature and moisture retrievals
developing improved methodology for systematic error correction for temperature and moisture retrievals
developing an on-line algorithm to compute Outgoing Longwave Radiation on a retrieval by retrieval basis.

The level 3 Path A parameters have been validated against independently measured data from both insitu and satellite sources. The errors quoted represent the "expected errors" using the RMS differences between the TOVS-derived values and the correlative values (area-weighted by latitude) summed over all gridboxes for a monthly period.

All retrievals are objectively validated according to the agreement between observed (cloud corrected) brightness temperatures for the temperature sounding channels and those computed from the solution. Two measures are used in this validation: the difference (residual) between observed and computed brightness temperatures for MSU channel 2, and the root mean square difference (rms error) between observed and computed brightness temperatures for the remainder of the temperature sounding channels. If either value is greater than 1 degree, the retrieval is rejected and a fill value is written out for all parameters except those related to cloud properties, which are always computed and written out. If each difference is less than 1 degree, a quality flag indicator is then computed based on the sum of the two measures as follows:

A quality flag value less than 1.0 indicates that the overall disagreement was rather small and the retrieval is assumed to be of very good quality. Quality flag values between 1.0 and 4.0 indicate an increasing difference between the observed and computed MSU channel 2 brightness temperatures and/or a higher RMS error for the remainder of the temperature sounding channels.

A checksum is used prior to data ingest to verify proper file transfer from the data producer to the archive center. Visual inspection of the level 3 data has been performed on a random basis using the IDL and Collage visualization packages to ensure proper HDF implementation and ready access to file contents.

Temperatures: Coarse layer temperatures are better defined by the TOVS radiances than point temperatures and therefore the results should be less method dependent provided effects of clouds on the radiances and sources of systematic errors are handled appropriately. The coarse layer temperatures are best determined in the order starting from the lower troposphere, with quantitative accuracy decreasing with increasing height. Interannual differences of monthly mean surface to 500 mb layer mean temperatures have high quantitative accuracy (better than 0.1 degree C) compared to radiosonde reports and spatial correlations greater than 0.95. They are therefore useful for global and regional trend studies as well as climate variability studies, such as spatial and temporal correlations between interannual differences of lower tropospheric temperature with those of other layer mean temperatures, surface skin temperature, water vapor distribution, clouds, and precipitation. Other layer mean temperatures are potentially less precise. They are best used for interannual variability studies and should be used for precise trend studies with care. As in all other parameters, retrievals over polar regions are more difficult for a number of reasons and expected error bars are larger, perhaps by a factor of 2, than elsewhere.

The products appear to be of sufficient accuracy to study interannual difference patterns and correlations in space and time between differences of surface and atmospheric quantities. Coarse layer temperatures and OLR are of high quantitative accuracy and may be useful for quantitative trend studies as well. The detailed temperature, moisture, and cloud distribution also provide information about the detailed factors entering the coarse layer temperatures and the OLR. See Limitations of the Data for more detailed information on dataset usage.

For long term measurement of trends, or even climate variability studies, it is important to be able to analyze data from different satellites without having appreciable intersatellite biases. There are two potential problems involved: different instrumentation and different time of day. It is expected that the Path A methodology of systematic error correction for temperature, moisture, and ozone will be accurate enough to account for intersatellite instrumentation differences. Differences in time of day are not accounted for directly. It is up to the user to account for time sampling differences in their interpretation of the data.


                                            Mean         Standard Deviation
          Parameter                    (NOAA9-NOAA10)      1 deg by 1 deg
          ---------                    -------------     ------------------
* Global surface skin temperature (C)       .37                1.58
  Sea surface temperature (C)               .07                0.47
* OLR (W/m2)                                .04                5.23
  Total Ozone (DU)                          .15                9.13
  Surf - 500 mb temp (C)                   -.17                0.89 
  500 mb - 300 mb temp (C)                  .07                0.86
  300 mb - 100 mb temp (C)                  .19                0.87
  100 mb - 30 mb temp (C)                   .06                0.82
  Total precip water (cm)                   .01                0.23
  Precip water above 850 mb (cm)           -.01                0.17
  Precip water above 700 mb (cm)            .00                0.09
  Precip water above 500 mb (cm)            .00                0.03
* Precipitation estimate (mm/day)           .06                0.80
* Cloud fraction (%)                       1.00                7.10
* Cloudtop pressure (mb)                   3.50               72.00

* Most sensitive to sampling difference in local time of day

Future plans involve processing the entire 16 year data set, 1979-1995, using a consistent algorithm, with completion by the end of calendar year1996. Based on what has been learned from the benchmark period, several improvements in the methodology are being considered. If these are made, the benchmark period will be reprocessed. The main improvement is a modification of the water vapor systematic error correction methodology so as to be independent of land or ocean surface. Also available are improved systematic error corrections for temperature profiles and total ozone. These improvements are currently being tested, while also using an improved version of the General Circulation model and data assimilation scheme which provides more accurate first guess water vapor fields.

Kidwell, K., 1991, NOAA Polar Orbiter Data User's Guide, NCDC/SDSD, National Climate Data Center, Washington, D.C.

Baker, W.E., 1983, "Objective Analysis and Assimilation of Observational Data from FGGE", Mon. Wea. Rev., 111, 328-342.

There are 2 FORTRAN programs developed by the DAAC, called TOVS_hdflist and TOVS_hdfdump, which can be used to read the data in the TOVS HDF files. These programs were designed and tested on SGI UNIX workstations only, but it should be quite easy to modify the FORTRAN code for use on other UNIX workstations as well as on VAX/VMS machines. The HDF calling interface library must be installed on your machine and linked to these programs during compilation.

The FORTRAN source code is available via FTP from the Goddard DAAC online system by request via the Document/Software List screen under the Options menu. They are distributed as a single tar file. To receive the software, log into the DAAC online system and request the tools from the Document/Software screen. To use the software, consult the documentation file automatically included along with the tar file.

Data can be obtained either by contacting the GSFC DAAC User Services Office listed above, or through the DAAC online IMS user interface. Telnet to :

Data can be ordered on the following media: 8mm tape (8200 or 8500 format), 4mm tape (60 or 90 meter), 9 track 6250 bpi, or by FTP. Magnetic tape requests can be mailed to the user, or picked up in person at the DAAC. For FTP requests, the user is notified by E-mail when the data have been staged and are ready for downloading.

NASA Official: Steve Kempler
Website Curator: Anthony Drake

Last updated: May 06, 2009 22:26:52 GMT

Additional Features

TOVS PATHFINDER PATH A DATASET GUIDE

Table of Contents

1. Document Information:

3. Dataset Information

4. Theory of Measurements:

5. Equipment:

6. Procedure:

7. Observations:

8. Data Granularity:

9. Data Description:

10. Data Manipulations:

11. Errors:

12. Notes:

Limitations of the Data:

13. Application of the Dataset:

14. Dataset Plans:

15. References:

16. Related Software:

17. Data Access:

18. Output Products and Availability:

19. Glossary of Terms:

20. List of Acronyms: