[Location: Location_Category='GEOGRAPHIC REGION', Location_Type='TROPICS']
TRMM Precipitation Radar (PR) Level 1 Power and Reflectivity Products (TRMM Product 1C21)Entry ID: GES_DISC_TRMM_1C21_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 1C21 calculates the effective radar reflectivity factor at 13.8 GHz without any propagation loss (due to rain or any other atmospheric gas) correction (Zm). Therefore, the Zm value can be calculated just by applying a radar equation for volume scatter with PR system parameters. The noise-equivalent Zm is about 21 dBZ. Through the subtraction of the system noise, the Zm value as small as 16 or 18 dBZ are still usable although the data quality is marginal. In 1C21, all echoes stored in 1B21 are converted to "dBZ" unit. This is not relevant for "non-rain" echo; however, this policy is adopted so that the 1B21 and 1C21 product format should be as close as possible except for the following points:
- Radar quantity is Zm in dBZ unit instead of received power (dBm).
- Data at echo-free range bins judged in 1B21 are replaced with a dummy
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 1C21)
Dataset Publisher: Goddard Space Flight Center Distributed Active Archive Center (GSFC DAAC)
Version: 7Online Resource: http://disc.gsfc.nasa.gov/datacollection/GES_DISC_TRMM_1C21_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: file size: 42958 kb
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