GES DISC DAAC Data Guide:
NOAA-NASA SSM/I Pathfinder Level 2 and Level 3 Precipitation Rate Products

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Summary:

The SSM/I Pathfinder Level 3 Precipitation Rate data set has been generated using the the Level 2 data, described above. The Level 2 data were interpolated to a longitude-latitude grid with a resolution of 1 degree. The data were weighted using a pixel weighting scheme to account for pixel overlap, which is dependant upon the location of the pixel within the scan and orbit. This weighting scheme was supplied by the algorithm developers. Once the weighting was done, the pixels were averaged over a period of time. The data were averaged over a period of either 5 days (a pentad) or an entire month. The data set, including both pentad and monthly grids, covers the period from 1 August 1987 through 31 December 1988.

Table of Contents:

• Data Set Overview
• Investigator(s)
• Theory of Measurements
• Equipment
• Data Acquisition Methods
• Observations
• Data Description
• Data Organization
• Data Manipulations
• Errors
• Notes
• Application of the Data Set
• Future Modifications and Plans
• Software
• Data Access
• Output Products and Availability
• References
• Glossary of Terms
• List of Acronyms
• Document Information

1. Data Set Overview:

Data Set Identification:

NOAA-NASA Pathfinder Level 2 and Level 3 Preciptation Rate from DMSP F-8.

Data Set Introduction:

The NOAA-NASA SSM/I Pathfinder Level 2 Precipitation Rate data set is created using the NOAA-NASA Pathfinder SSM/I data set which contain antenna temperature data as input. Each SSM/I Pathfinder Precipitation Rate file begins with the first scan after 00:00:00 UTC and contains all data up to 23:59:59 UTC. The files are in Hierarchical Data Format (HDF). The file size for an uncompressed SSM/I Pathfinder daily precipitation rate file is 50 megabytes.

The NOAA-NASA SSM/I Pathfinder Level 3 Precipitation Rate data set is created using the NOAA-NASA Pathfinder SSM/I Level 2 Precipitation Rate data set, which contain full-resolution precipitation rate data, as input. Each SSM/I Pathfinder Precipitation Rate file begins with the first scan after 00:00:00 UTC of the first day of the gridding period and contains all data up to 23:59:59 UTC of the last day of the gridding period. The gridding period may be either a calendar month or a pre-determined group of 5 days within the year, known as a pentad. The files are in Hierarchical Data Format (HDF). The file size for an uncompressed SSM/I Pathfinder gridded precipitation rate file is about 0.8 megabytes.

Objective/Purpose:

The objective of producing the NOAA-NASA SSM/I Pathfinder Level 2 and Level 3 Precipitation Rate data set is to provide long-term research quality global data for global change research.

Summary of Parameters:

The parameters for the Level 2 Precipitation Rate data set are:

• 12.5-km resolution, swath format Precipitation Rates
• Confidence Flag/Surface Type
• File Description
• Latitude Values
• Longitude Values
• Scan Start Times
• Orbit Parameters
• Precipitation Rate Image.

The parameters for the Level 3 Precipitation Rate data set are:

• Precipitation Rate grid, 1 degree longitude-latitude format
• The Sum of the Squares grid
• The Number of Pixels grid

Discussion:

A complete discussion of the Level 2 data sets is available from the NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) and for the Level 3 Precipitation Rate is available from NOAA/NASA SSM/I Pathfinder Pentad and Monthly Precipitation Rate Data Sets .

Related Data Sets:

The following related data sets are available from the Goddard Space Flight Center (GSFC) Distributed Active Archive Center (DAAC):

Chang SSM/I Derived Ocean Monthly Rain Indices
GPCP Combined Precipitation
Arkin & Janowiak GPCP Satellite Derived Monthly Rainfall
Jaeger Monthly Mean Global Precipitation
Legates Surface and Ship Observation of Precipitation
GPCC Rain Gauge Analysis for GPCP

2. Investigator(s):

Investigator(s) Name and Title:

Data Investigators:

    Dr. Robert Adler
    Code 912
    NASA Goddard Space Flight Center
    Greenbelt, MD 20771 USA
    Internet: adler@agnes.gsfc.nasa.gov
    301-286-9086 (voice)
    301-286-1762(fax)
 
    and
 
    Dr. George Huffman
    Code 912
    NASA Goddard Space Flight Center
    Greenbelt, MD 20771 USA
    Internet: huffman@agnes.gsfc.nasa.gov
    301-286-9785 (voice)
    301-286-1762(fax)
     
    

Data Producer

    Mr. Michael Goodman
    Global Hydrology and Climate Center
    ES 44
    NASA Marshall Space Flight Center
    977 Explorer Blvd
    Huntsville, AL 35806  USA
    Telephone Numbers:(205) 922-5890
    Internet: michael.goodman@msfc.nasa.gov
   

Title of Investigation:

NOAA-NASA Pathfinder Special Sensor Microwave / Imager (SSM/I) Level 2 and Level 3 Precipitation Rate Data Set.

Contact Information:

Please direct all queries to Goddard Space Flight Center (GSFC) DAAC Help Desk.

DAAC Help Desk:

The DAAC Help Desk also provides additional information on the Goddard DAAC system capabilities, and other supported datasets. The Help Desk can be reached at:

EOS Distributed Active Archive Center (DAAC)

Code 610.2

NASA Goddard Space Flight Center

Greenbelt, Maryland 20771

Internet:daacuso@daac.gsfc.nasa.gov

301-614-5224 (voice)

301-614-5268 (fax)

3. Theory of Measurements:

The GSCAT2 algorithm uses the natural properties of microwave energy to determine instantaneous precipitation rates within the area defined by the pixel. Upwelling microwave energy is scattered by ice crystals which are usually present during different phases of the lifetime of convection and other precipitating systems. The GSCAT2 uses the various operating channels of the SSM/I to first mask off pixels as "no rain" which do not meet the criteria to be labelled as "rain". This masking includes surface features such as melting snowpack, cold ocean, desert sand and land-water interfaces. The remaining pixels (which are unmasked) are then converted to instantaneous precipitation rates. The precipitation rate (in mm/hr) is inversly proportional to the brightness temperature; therefore, a cutoff value of 247 K (which equals 1 mm/hr) is used as the maximum temperature (minimum intensity) in the equation. Some unmasked pixels have a lower confidence than others; these are called "ambiguous" and are flagged as such in the Confidence/Surface Type object.

The GSCAT2 algorithm output is used to create pentad and monthly grids of precipitation rate. The full-resolution output is weighted using a pixel weighting scheme supplied by the GSCAT2 algorithm developers. This weighting scheme is used to account for the varying amount of pixel overlap which is dependant upon the location within the scan and orbit. Once the data has been weighted, it is interpolated to a 1 degree by 1 degree longitude-latitude grid. This grid is aligned such that the left side of the grid corresponds to 180 degrees longitude. Thus, the grid location (1,1) corresponds 180-179 degrees west longitude, 90-89 degrees north latitude.

No flagged values are used in computing any of the gridded values. In fact, counts of the ambiguous and cold surface pixels are kept for each grid box. If the percentage of the sum of these pixels exceeds a preset threshold, then the grid box is flagged as having bad or low confidence data, and no average is given. Grid boxes with no data are also flagged.

4. Equipment:

SSM/I Instrument Description:

The information marked with an asterisk (*) in Section 5: Equipment, is quoted from:

Hollinger, J. P., J. L. Peirce, and G. A. Poe, 1990: SSM/I instrument evaluation. IEEE Transactions on Geoscience and Remote Sensing, 28(5), 781-790.

The SSM/I consists of an offset parabolic reflector illuminated by a corrugated broad-band, seven port horn antenna. The reflector and feed-horn antenna are mounted on a drum which contains the radiometers, digital data subsystem, mechanical scanning subsystem, and power subsystem. The entire reflector, feed horn, and drum assembly is rotated about the axis of the drum by a coaxially mounted bearing and power transfer assembly (BAPTA). All data, commands, timing and telemetry signals, and power pass through it on slip ring connectors to the rotating assembly.

Collection Environment:

The SSM/I is a passive microwave sensor aboard the operational DMSP F-8 polar orbiting satellite.

Platform:

The DMSP Block 5D-2 F-8 spacecraft flies in a near polar sun-synchronous orbit. Launched on 18 June 1987, the satellite completes 14.1 revolutions per day, the subsatellite ground track repeats approximately every 16 days.

Platform Mission Objectives:

The mission of the DMSP is to provide global, visual and infrared cloud data and other specialized near real-time meteorological, oceanographic and solar-geophysical data required to support worldwide Department of Defense operations and high-priority programs. Timely data are supplied to Air Force Global Weather Central (AFGWC), the Navy Fleet Numerical Meteorology and Oceanography Center (FNMOC) and to deployed tactical receiving terminals worldwide.

Key Variables:

Operational parameters include the following orbital elements:

Nominal altitude: 833 km

Inclination: 98.8 degrees

Nodal period: 102 minutes

Equator crossing: 0612 (ascending local time)

Principles of Operation:

The SSM/I is a seven-channel, four-frequency linearly polarized passive microwave radiometric system. The instrument measures atmospheric, land and ocean surface brightness temperatures at 19.3, 22.2, 37.0 and 85.5 GigaHertz (GHz).

Instrument Measurement Geometry:

The SSM/I rotates at a uniform rate making one revolution in 1.9 seconds, during which time the satellite advances 12.5 km. The antenna beams are at an angle near 45 degrees to the BAPTA rotational axis, which is normal to the earth's surface. Thus, as the antenna rotates, the beams define the surface of a cone and, from the orbital altitude of 833 km, make an angle of incidence of 53.1 degrees at the earth's surface.

The scene is viewed over a scan angle of 102.4 degrees centered on the ground track aft of the satellite, resulting in a scene swath width of 1394 km.

For a discussion of channel sampling methods, please refer to Sensor Measurement Geometry.

Manufacturer of Instrument:

The SSM/I was built by Hughes Aircraft Company under the direction of the Naval Space Systems Activity and the Air Force Space Division.

SSM/I Calibration:

A small mirror and hot reference absorber are mounted on the BAPTA and do not rotate with the drum assembly. They are positioned off-axis such that they pass between the feed horn and the parabolic reflector, occulting the feed once each scan. The mirror reflects cold sky radiation into the feed thus serving, along with the hot reference absorber, as calibration references for the SSM/I.*

This scheme provides an overall absolute calibration which includes the feed horn. Corrections for spillover and antenna pattern effects from the parabolic reflector are incorporated in the data processing algorithms.

For a complete discussion of the SSM/I calibration, please refer to SSM/I Instrument Evaluation (Hollinger et al. 1990).

5. Data Acquisition Methods:

The Antenna Temperature (Ta) data used for the SSM/I Pathfinder Project are provided by Remote Sensing Systems of Santa Rosa, California and are originally derived from the Temperature Data Records (TDR) processed at the FNMOC in Monterey, California. This data is processed at MSFC into the NOAA-NASA SSM/I Pathfinder Ta data set, which is then used as input to create the NOAA-NASA SSM/I Pathfinder Level 2 Precipitation Rate data set, using the GSCAT2 algorithm.

The SSM/I Pathfinder Level 2 Precipitation Rate data set is then used to generate the NOAA-NASA SSM/I Pathfinder Level 3 Precipitation Rate data set. The Level 2 output is binned, averaged, and flagged as describe in Section 3. Theory of Measurements . For details on the processing of the Level 2 data sets, see the NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) and for the Level 3 data sets, see NOAA/NASA SSM/I Pathfinder Pentad and Monthly Precipitation Rate Data Sets.

6. Observations:

Data Notes:

No notes at this time.

Field Notes:

No field notes.

7. Data Description:

Spatial Characteristics:

Spatial Coverage:

Coverage of the Pathfinder Level 2 and Level 3 Precipitation Rate data sets is global.

Spatial Coverage Map:

For the spatial coverage map, blue indicates areas where good data can occur within the grid, black indicates where good data can not occur within the grid, and gold indicates the coastal outlines.

Spatial Resolution:

The Pathfinder Level 2 Precipitation Rate data set has been produced at full resolution (12.5 km).

The Pathfinder Level 3 Precipitation Rate data set has been produced at a resolution of 1 degree in latitude and longitude.

Projection:

The Pathfinder Level 2 Precipitation Rate data set has been produced in swath format.

The Pathfinder Level 3 Precipitation Rate data set has been produced in a equirectangular cylindrical projection.

Grid Description:

The Pathfinder Level 3 Precipitation Rate data set uses an equal-angle (longitude-latitude) grid with each grid box corresponds to an equal interval of latitude and longitude.

Temporal Characteristics:

Temporal Coverage:

Both data sets cover the period from 1 August 1987 to 31 December 1988, which includes the Pathfinder Benchmark Period (1 August 1987 to 30 November 1988). On December 3, 1987, the F-8 SSM/I instrument was turned off due to overheating. It was turned on again on January 13, 1988. No data was taken during this period, and thus neither data set contains products from this period. Several other small gaps are also in the data. for more information about gaps in the data.

Temporal Coverage Map:

This map provides the temporal distribution of the available SSM/I data used to derive the precipitaiton rate products.

Temporal Resolution:

The Level 2 data set is available at a resolution of one day.

The Level 3 Pentad data set is available at a resolution of 5 days.

The Level 3 Monthly data set is available at a resolution of one month.

Data Characteristics:

Parameter/Variable:

Average precipitation rate, in mm/day (for the Level 3 data) or in mm/hr (for the Level 2 data).

Variable Description/Definition:

The variable measured is an instantaneous precipitation rate, in mm/hr for the Pathfinder Level 2 data set (the precipitation rates are averaged and then converted to mm/day for the Level 3 data set). Instantaneous precipitation rate refers to the fact that the variable is a rate of accumulation of precipitation, measured at the exact moment that the instrument samples the area in question.

Unit of Measurement:

For the Level 2 Precipitation Rate data set, the units are average precipitation rate in mm/hr * 10.0

For the Level 3 Precipitation Rate data set, the units are average precipitation rate in mm/day * 100.0

Data Source:

The data from which the Pathfinder Level 2 Precipitation Rate data are generated come from the DMSP F-8 SSM/I instrument.

Data Range:

For the Level 2 Precipitation Rate data set, the range of unscaled values is 0 - 100 mm/hr

For the Level 3 Precipitation Rate data set, the range of unscaled values is 0 - 2400 mm/day

Sample Data Record:

For a description of the type of objects included in the Level 2 Precipitation Rate files, refer to the NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) and for the Level 3 Precipitation Rate files, refer to NOAA/NASA SSM/I Pathfinder Pentad and Monthly Precipitation Rate Data Sets .

8. Data Organization:

Data Granularity:

A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.

For the Level 2 products, data is stored in daily files by orbit. The DMSP satellite completes just over 14 orbits each day. An orbit is defined as starting when the satellite crosses the equator going from south to north. Since (swath) data is stored by time, it's possible to have a fraction of an orbit before the first and last full orbits in a particular day's file. Missing data is flagged, such that any data falling on the previous or following days (before 00:00:00 or after 23:59:59 UTC of the current day) will not be present and the scan position will be filled with a missing data flag.

For the Level 3 products, data are stored as grids to which all orbits for a given period (i.e., either a pentad or a month) have been interpolated.

Data Format:

All of the data in the Pathfinder Level 2 and Level 3 data sets are stored in Heirarchical Data Format (HDF).

9. Data Manipulations:

Formulae:

The TB rain rate equation used over land surfaces is

TB = 251.0 - (4.19 * R)

where TB is the brightness temperature and R is the precipitation rate in mm/hr.

For temperatures over an ocean surface, the equation is

TBocean = 251.0 - (2.09 * R)

where R is as defined above and TBocean is the brightness temperature over an ocean. Over the coastal regions, the slope (multiplier for the precipitation rate R) is an average of the land and ocean values.

Derivation Techniques and Algorithms:

The above formulae are derived statisitically from microwave modelling observations. For more information, refer to the list of references in the NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) .

Data Processing Sequence:

Processing Steps:

The antenna temperature data are read into the processing software, and, scan by scan, are checked for data quality. The 19, 22, and 37 GHz channels are interpolated to match the resolution of the 85 GHz channels. The data from the channels is then used to screen each of the 85 GHz horizontal polarization pixels for a precipitation signature. A linear regression equation is then applied to the 85 GHz pixels which have been selected as having precipitation. This data is output as the Level 2 Precipitation Rate data.

These data are then used to create the Level 3 Precipitation Rate data. The precipitation rates are interpolated to a 1 degree latitude-longitude grid, after a pixel-weighting scheme has been applied. Any grid bin populated by ambiguous (low confidence) data or cold surface (ice surface) data above a certain threshold is flagged as bad. These data are output as the Level 3 Precipitation Rate data

A discussion of the Level 2 processing sequence can be found in the NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) and for the Level 3 processing sequence, refer to NOAA/NASA SSM/I Pathfinder Pentad and Monthly Precipitation Rate Data Sets .

Processing Changes:

No changes have been made to the processing sequence.

Calculations:

Special Corrections/Adjustments:

No enhancements were made to the GSCAT2 algorithm, except to enable the algorithm to accept the NOAA-NASA Pathfinder Antenna Temperature data set as input.

Calculated Variables:

The only calculated variable is the precipitation rate.

Graphs and Plots:

No graphs or plots are available.

10. Errors:

Sources of Error:

No information on error sources is available at this time.

Quality Assessment:

Data Validation by Source:

Studies have been conducted by the GSCAT2 algorithm developers. Refer to the list of references available in NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) for information on the data validation.

Confidence Level/Accuracy Judgement:

The NOAA/NASA Pathfinder Team believes this data set to be an accurate representation of the algorithm as developed by the GSCAT2 algorithm developers.

Measurement Error for Parameters:

There is no data about the measurement error at this time.

Additional Quality Assessments:

The algorithm was implemented to use SSM/I Pathfinder Antenna Temperature data sets as input, and the Level 2 and Level 3 output were reviewed by the algorithm developers to ensure that the algorithm had been properly implemented.

Data Verification by Data Center:

The Pathfinder Level 2 and Level 3 Precipitation Rate data have been through a rigorous quality control procedure, and both data sets are judged to be accurate representations of the algorithm. For details, contact the GSFC DAAC Help Desk Office.

11. Notes:

Limitations of the Data:

This algorithm is a scattering algorithm and will primarily identify convective precipitation. Stratiform precipitation will be underestimated.

Known Problems with the Data:

The algorithm will sometimes define pixels of precipitation rate as "ambiguous" which indicates a lower confidence in the existence of precipitation at that pixel. Sometimes these ambiguous pixels are the result of surface ice or snow melting. The user should be cautious when using these pixels in large scale precipitation studies. A significant number of ambiguous pixels should be viewed as suspect data.

The algorithm will also label pixels as "cold surface", which are associated with snow/ice fields. No precipitaion is associated with cold surface pixels. Precipitation rates which are co-located with a large number of "cold surface" pixels should also be treated as suspect data.

All reference materials refer to brightness temperatures; however, at the direction of the algorithm developers, antenna temperatures were used in the computation of the precipitation rates.

In some of the Level 3 pentad grids, there are bins which are obviously ambiguous precipitation rates, although they are not flagged. This is due to the higher ambiguous/cold surface threshold used in the pentad processing (40%) as opposed to the lower threshold of the monthly processing (20%). This allows a precipitation rate average to be calculated even at the occurrence of higher ambiguous/cold surface counts. Most of these bins occur in the far Norhtern Hemisphere polar region during the summer months

Usage Guidance:

See Section 11.2 Known Problems with the Data above for usage guidance.

Any Other Relevant Information about the Study:

No other information at this time.

12. Application of the Data Set:

Monitoring of global precipitation.

13. Future Modifications and Plans:

Please Note: These files were generated and archived at MSFC. Recently the SSM/I pathfinder dataset is moved to Goddard DAAC. The file description written in each file has not been updated for the new point of contact and user service mail address since in few months this data will be replaced with the new version of SSM/I path finder data produced by Drs. Adler and George Huffman group at Goddard NASA. However for more information on the existing data and informations on the old and new algorithms please contact the Goddard Space Flight Center DAAC Help Desk.

14. Software:

Software Description:

Three pieces of software are sent with the Level 2 Precipitation Rate data as utilities to aid in handling the data within the files. The routines are "extractpr.c", "getorbpr.c", and "getfiledesc_pr.c". A makefile is also sent along to compile this software. The user will also need to access NCSA's HDF library software, which is free from NCSA via ftp. A README is also sent along with the data to help the user understand the files and the data.

Three pieces of software are sent with the Level 3 Precipitation Rate data as utilities to aid in handling the data within the files. The routines are "extractrg.c", "getfiledesc.c" and "read_bin.c". A makefile is also sent along to compile this software. The user will also need to access NCSA's HDF library software, which is free from NCSA via ftp. Documentation is also sent along with the data to help the user understand the files and the data.

For more information about the Level 2 software and how to use it, refer to NOAA/NASA Special Sensor Microwave/ Imager (SSM/I) Pathfinder Daily Precipitation Rate Data (Level 2) and for the Level 3 software, see NOAA/NASA SSM/I Pathfinder Pentad and Monthly Precipitation Rate Data Sets.

Software Access:

To access information about how to retrieve the HDF libraries, please refer to the Goddard DAAC HDF Information Page

15. Data Access:

Contact Information:

Goddard Space Flight Center DAAC Help Desk.

Data Center Identification:

GSFC Distributed Active Archive Center

Procedures for Obtaining Data:

This data set is available via several ways: by contacting the GSFC DAAC Help Desk, by accessing the Goddard DAAC Prepackaged Tape Ordering System via the WWW interface, or Anonymous FTP.

GSFC DAAC Help Desk:

The DAAC Help Desk also provides additional information on the Goddard DAAC system capabilities, and other supported datasets. The Help Desk can be reached at:

     EOS Distributed Active Archive Center (DAAC)
     Code 610.2
     NASA Goddard Space Flight Center
     Greenbelt, Maryland 20771
     Internet:daacuso@daac.gsfc.nasa.gov
     301-614-5224 (voice)
     301-614-5268 (fax)
      

ANONYMOUS FTP:

The Precipitation Global Data Set also resides on-line at the Goddard DAAC anonymous FTP and may be accessed either directly from this document,

SSM/I Pathfinder Daily Precipitation

SSM/I Pathfinder Pentad Precipitation

SSM/I Pathfinder Monthly Precipitation

or can be acessed via FTP at

ftp daac.gsfc.nasa.gov

login: anonymous

password: < your internet address >

cd http://disc.sci.gsfc.nasa.gov/data/precipitation/precip/ssmi_pathf_monthly(pentad or daily)

Data Center Status/Plans:

The GSFC DAAC plans to periodically check with the data producer regarding updates to the data set.

16. Output Products and Availability:

Data sets are provided on 8 mm tapes, or via FTP.

17. References:

Satellite/Instrument/Data Processing Documentation:

• Hollinger, J. P., R. Lo, G. Poe, R. Savage, and J. Peirce,1987: Special Sensor Microwave/Imager User's Guide.
• Hollinger, J. P., ed, 1989: DMSP Special Sensor Microwave/Imager Calibration/Validation Final Report Volume 1.
• MSFC DAAC Users Guide to Special Sensor Microwave Imager (SSM/I) Data (NESDIS Level 1b Format), 1993: George C. Marshall Space Flight Center Distributed Active Archive Center, pub.
• Wentz, F.J., 1991: User's Manual SSM/I Antenna Temperature Tapes (Revision 1).

Journal Articles and Study Reports:

• Adler, Robert F., A. J. Negri, P. R. Keehn, and I. M. Hakkarinen, 1993: Estimation of Monthly Rainfall over Japan and Surrounding Waters from a Combination of Low-Orbit Microwave and Geosynchronous IR Data. Journal of Applied Meteorology, 32, 335-356.
• Adler, Robert F., H.-Y. M. Yeh, N. Prasad, W.-K. Tao and J. Simpson, 1991: Microwave Simulations of a Tropical Rainfall System with a Three-Dimensional Cloud Model. Journal of Applied Meteorology, 30, 924-953.
• Adler, Robert F., G. J. Huffman, and P. R. Keehn, 1994: Global Tropical Rain Estimates From Microwave-adjusted and Geosynchronous IR Data. Remote Sensing Reviews, in press.
• Hollinger, J. P., J. L. Peirce, and G. A. Poe, 1990: SSM/I Instrument Evaluation. IEEE Transactions on Geoscience and Remote Sensing, 28(5), 781-790.

18. Glossary of Terms:

EOSDIS glossary

19. List of Acronyms:

EOSDIS acronyms

Other Terms:

NOAA: National Oceanic and Atmospheric Administration

NASA: National Aeronautics and Space Administration

DMSP: Defense Meteorological Satellite Program

SSM/I: Special Sensor Microwave/Imager

GSCAT2: Goddard Scattering Algorithm Version 2

HDF: Hierarchical Data Format

Ta: Antenna Temperature

Tb: Brightness Temperature

PR: Precipitation Rate

mm: millimeter

GHz: Gigahertz

20. Document Information:

Document Revision Date:Fri May 10 11:53:16 EDT 2002

March 11, 1997

Document Review Date:

March 11, 1997

Document ID:

Intentionally left blank

Citation:

Intentionally left blank

Document Curator:

Hydrology Data Support Team (hydrology@daac.gsfc.nasa.gov)

Document URL: