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TRMM 3G68 hourly rainfall rate

Version 6 TMI,PR observed houly rain rate

3G68 is an hourly gridded product containing TRMM instrument rain estimate. 3G68 contains the rain information from 2A12, 2A25 and 2B31.

A number of climate rainfall products are produced from the passive microwave (TMI) and precipitation radar (PR) sensors on board the Tropical Rainfall Measuring Mission (TRMM) satellite, which was launched in November of 1997. The TRMM monthly or climate rainfall products, referred to as the level 3 products, are derived primarily from accumulations of the TRMM level 2 products, or instantaneous rainfall estimates corresponding to the original satellite snapshot views. The availability of multiple rainfall products from the various TRMM rainfall sensors is due to the fact that each one has various strengths and weaknesses. As a result, the "best" rainfall estimate is application dependent. The TRMM PR provides the highest spatial resolution (~4 km), most information content, the best vertical resolution (80 levels), and the most directly measured surface rainfall estimates for many application. The swath width of the PR, however, is around 1/3 of the TMI swath width resulting is significantly poorer sampling for many climate applications.

3G68 is an hourly gridded text (ascii) product containing TRMM 2A12 [Kummerow etal., 2001], 2A25 [Iguchi et al., 2000], and 2B31 [Haddad et al., 1997a, 1997b], rain estimates. The 3G68 product includes 24 hour of hourly grids into a single daily file. The combination of the rain estimates on a common 0.5 x 0.5 degree grid provides an easy way to compare instantaneous results from the three retrieval algorithms. Note that this is not a standard TRMM product

References:

• Haddad, Z. S., E. A. Smith, C. D. Kummerow, T. Iguchi, M. R. Farrar, S. L. Durden, M. Alves, and W. S. Olson, 1997a: The TRMM `Day-1' Radar/Radiometer Combined Rain-Profiling Algorithm", J. Meteor. Soc. Japan, 75, 799-809.
• Haddad, Z. S., D. A. Short, S. L. Durden, E. Im, S. Hensley, M. B. Grable and R.A. Black, 1997b: "A New Parametrization of the Rain Drop Size Distribution", IEEE Trans. Geosci. Rem. Sens., 35, 532-539.
• Iguchi, T., T. Kozu, R. Meneghine, J. Awaka, and K. Okamoto, 2000: Rain-profiling algorithm for the TRMM precipitation radar, J. Appl. Meteor., 39, 2038-2052
• Kummerow, C. Y. Hong, W. S. Olson, S. Yang, R. F. Adler, J. McCollum, R. Ferraro, G. Petty, D. B. Shin, and T. T. Wilheit, 2001: The evolution of the Goddard profiling algorithm (GPROF) for rainfall estimation from passive microwave sensors, J. Appl. Meteor., 40, 1801-1840.

IMPORTANT: TRMM PR Data Unavailable After Oct. 07, 2014 Due to Satellite Descent

As the descent of TRMM is underway users of TRMM PR data should be aware that the last production orbit of public PR data will be orbit #96230 on data date Oct. 7, 2014. After this time the TRMM PR data is restricted.  TRMM TMI data will continue to be produced and publicly available during the descent of the spacecraft until it reaches its decommissioning altitude of 335km.

Variables	TMI convective percentage (%), PR convective percentage (%), PR and TMI combined convective percentage (%)
Zonal	Global by 0.5 deg
Meridional	40S to 40N by 0.5 deg
Vertical	one level
Temporal	Dec 21, 1997 to Oct 6, 2014 by 1 hour
Static?	yes
Volume	11.8 Gbytes/year
Server	public:
Source	ftp://trmmopen.gsfc.nasa.gov/pub/
Acquired	Mar 28, 2006 (Updated Jan 2015)
APDRC contact	/
Supplements	README.3G68