[Personnel: Last_Name='HYDROLOGY DATA SUPPORT TEAM']
TRMM Precipitation Radar (PR) Level 1 Power and Reflectivity Products (TRMM Product 1B21)Entry ID: GES_DISC_TRMM_1B21_V7
Abstract: The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating.
The TRMM Precipitation Radar (PR), the first of its kind in space, is an electronically scanning radar, operating at 13.8 GHz that measures the 3-D rainfall distribution ... over both land and ocean, and defines the layer depth of the precipitation.
The 1B21 calculates the received power at the PR receiver input point from the Level-0 count value which is linearly proportional to the logarithm of the PR receiver output power. To convert the count value to the input power, extensive internal calibrations are applied, which are mainly based upon the system model, temperature dependence of model parameters and many temperature sensors attached at various locations of the PR. Periodically the input-output characteristics are measured using an internal calibration loop for the IF unit and later receiver stages. To make an absolute calibration, an Active Radar Calibrator (ARC) is placed at Kansai Branch of CRL and overall system gain of the PR is being measured every 2 months. Using the transfer function based on the above internal and external calibrations, the PR received power is obtained. Note that the value assumes that the signal follows the Rayleigh fading, so if the fading characteristics of a scatter is different, a small bias error may occur (within 1 or 2 dB).
The data are stored in the Hierarchical Data Format (HDF), which includes both core and product specific metadata applicable to the PR measurements. A file contains a single orbit of data with a file size of about 139 MB (uncompressed). The HDF-EOS "swath" structure is used to accommodate the actual geophysical data arrays. There are 16 files each of PR 1B21 and 1C21 data produced per day.
Spatial coverage is between 38 degrees North and 38 degrees South, owing to the 35 degree inclination of the TRMM satellite. This orbit provides extensive coverage in the tropics and allows each location to be covered at a different local time each day, enabling the analysis of the diurnal cycle of precipitation. There are, in general, 9150 scans along the orbit, with each scan consisting of 49 rays. The scan width is about 220 km.
Data Set Citation
Dataset Originator/Creator: NASA,JAXA, Tropical Rainfall Measuring Mission (TRMM)
Dataset Title: TRMM Precipitation Radar (PR) Level 1 Power and Reflectivity Products (TRMM Product 1B21)
Dataset Publisher: Goddard Space Flight Center Distributed Active Archive Center (GSFC DAAC)
Version: 7Online Resource: http://disc.gsfc.nasa.gov/datacollection/GES_DISC_TRMM_1B21_V7.shtml
Start Date: 1997-12-07
Latitude Resolution: 4 km
Longitude Resolution: 4 km
Horizontal Resolution Range: 1 km - < 10 km or approximately .01 degree - < .09 degree
Vertical Resolution: 125-250 m
Vertical Resolution Range: 100 meters - < 1 km
Temporal Resolution: 16 orbits per day
Temporal Resolution Range: Daily - < Weekly
ISO Topic Category
Quality A Table structure (called Scan Status) is included in the HDF file,
containing entries on a scan-by-scan basis. These entries include a
geolocation flag and a data quality flag, indicating the percentage of
pixels along each scan with values within a pre-defined range.
Access Constraints None
Data Set Progress
Distribution Media: FTP
Distribution Size: 15-16 files /day; 80,000 - 81,000 KB/file
Distribution Format: HDF
Role: TECHNICAL CONTACT
Email: gsfc-help-disc at lists.nasa.gov
Goddard Earth Sciences Data and Information Services Center Code 610.2 NASA Goddard Space Flight Center
Province or State: MD
Postal Code: 20771
Role: DIF AUTHOR
Email: Zhong.Liu-1 at nasa.gov
NASA Goddard Space Flight Center Mailstop 610.2
Province or State: MD
Postal Code: 20771
File Specifications for TRMM Products: http://pps.gsfc.nasa.gov/Documents/filespec.TRMM.V7.pdf
Metadata for TRMM Products: http://pps.gsfc.nasa.gov/Documents/filespecMeta.TRMM.V7.pdf
TRMM V6 vs. V7 Major Data Format Changes: http://pps.gsfc.nasa.gov/Documents/formatChangesV7.pdf
T. Kozu, T. Kawanishi, K. Oshimura, M. Satake, H. Kumagai; TRMM
... precipitation radar: calibration and data collection strategies, Proc.
M. Satake, K. Oshimura, Y. Ishido, S. Kawase, T. Kozu: TRMM PR data
processing and calibration to be performed by NASDA, Proc. IGARSS'95,
426-428, Florence, 1995.
Interface Control Specification Between the Tropical Rainfall Measuring
Mission Science Data and Information System (TSDIS) and the TSDIS Science
User (TSU). Volume 3: File Specifications for TSDIS Products-Level 1. NASA
Goddard Space Flight Center, March 31, 1999.
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2011-07-15
Last DIF Revision Date: 2014-09-11