Comparisons of rainrates from 3B42, IMERG Final-Run and MRMS
3B42TMPA 3B42 files are avaliable from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). These gridded estimates are on a 3-hour temporal resolution and a 0.25-degree by 0.25-degree spatial resolution in a global belt extending from 50S to 50N. The 3B42 estimates are produced in four stages:
(2) infrared precipitation estimates are created using the calibrated microwave precipitation;
(3) the microwave and IR estimates are combined;
(4) rescaling to monthly data is applied. Each precipitation field is best interpreted as the precipitation rate effective at the nominal observation time.
IMERGIntegrated Multi-Satellite Retrievals for GPM (IMERG) Algorithm is intended to intercalibrate, merge, and interpolate "all" satellite microwave precipitation estimates, together with microwave-calibrated infrared (IR) satellite estimates, precipitation gauge analyses, and potentially other precipitation estimators at fine time and space scales for the TRMM and GPM eras over the entire globe. The system is run several times for each observation time, first giving a quick estimate and successively providing better estimates as more data arrive. The final step uses monthly gauge data to create research-level products. Background information and references are provided to describe the context and the relation to other similar missions. Issues involved in understanding the accuracies obtained from the calculations are discussed. Throughout, a baseline Day-1 product is described, together with options and planned improvements that might be instituted before or after launch depending on maturity and project constraints. The IMERG gridded estimates are on a 30-minute temporal resolution and a 0.1-degree by 0.1-degree spatial resolution extending from 180W to 180E and 60S to 60N. For more information about IMERG, downlad IMERG_ATBD_V4.4.pdf Thanks to George Huffman and David T. Bolvin for providing the pre-launch "test-version" of IMERG data (03-28 Jun 2012) and IMERG Final Run research product (V03D: 12 Mar 2014 - 31 Jan 2016; V04A: 12 Mar 2014 - Present).
Comparisons with MRMSThe comparisons are conducted over the CONUS (20N-50N, 125W-65W) using 3B42, IMERG and MRMS data during the commonly available periods:
TEST: Jun 2012
V03D: Apr 2014 - Jan 2016
V04A: Apr 2014 - May 2016