H11O-04
The First Year of Day-1 IMERG Data and Future Directions

Monday, 14 December 2015: 08:45
3022 (Moscone West)
George John Huffman1, David T Bolvin2, Dan Braithwaite3, Kuo-lin Hsu3, Robert Joyce4, Christopher Kidd5, Eric J. Nelkin2, Soroosh Sorooshian3 and Pingping Xie6, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)Science Systems and Applications, Inc., Lanham, MD, United States, (3)Univ California Irvine, Irvine, CA, United States, (4)NOAA/NCEP/CPC, Boca Raton, FL, United States, (5)Earth System Science Interdisciplinary Center, COLLEGE PARK, MD, United States, (6)NOAA/NCEP, College Park, MD, United States
Abstract:
The Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm merges precipitation estimates from the international constellation of low-Earth-orbit microwave and geostationary-Earth-orbit infrared satellites. The GPM Core Observatory instruments provide intercalibration data, and a monthly surface precipitation gauge analysis is incorporated as well. IMERG is a unified U.S. algorithm based on code from groups at NASA Goddard Space Flight Center, NOAA Climate Prediction Center, and Univ. of California Irvine’s Center for Hydrometeorology and Remote Sensing. Due to differing latency requirements from different classes of users, data sets are computed at 6 hours, 16 hours, and 3 months after observation time, referred to as Early, Late, and Final Runs, respectively. The Day-1 products cover the latitude band 60°N-S on a 0.1°x0.1°grid, with half-hourly data starting on 1 April 2015, 7 March 2015, and 10 March 2014 for the Early, Late, and Final, respectively.

The presentation will briefly outline the various data fields provided in the IMERG data files, including precipitation estimates and precipitation phase. The performance of the IMERG estimates will be discussed, including comparisons among the near-real-time “Early” and “Late” Runs and the research-quality “Final” Run. Early results show that IMERG is competitive with the current TRMM Multi-satellite Precipitation Analysis (TMPA) estimates, even with the pre-GPM calibrations that are used in Day-1 IMERG and the input precipitation estimates. One important result is that the “morphed” data values have bulk difference statistics that are similar to the statistics for many of the individual sensors. In about March 2016 the GPM era will be reprocessed with improved, fully GPM-based algorithms. About a year later IMERG will be extended to cover the period 1998 to the present. The talk will summarize the transition from the legacy TMPA to IMERG.

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