Rainfall

Global Precipitation Climatology Project (GPCP)

GPCP combines the precipitation information available from each of several sources into a final merged product, taking advantage of the strengths of each data type. The microwave estimates are based on Special Sensor Microwave/Imager (SSM/I) data from the Defense Meteorological Satellite Program (DMSP, United States) satellites that fly in sun-synchronous low-earth orbits. The current products include global monthly 2.5o and daily 1o rainfall estimates. The monthly data extends from 1979 to current, while the daily product is from 1996 to present. Both products are made available with some time delay.

From the IRI Data Library: 1-degree daily combination precipitation estimates and Monthly 2.5 degree

CPC Merged Analysis of Precipitation (CMAP)

CMAP is produced by the National Oceanographic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC) at a spatial resolution of 2.5o with pentad (five-day) and monthly aggregations. This technique produces global precipitation in which observations from rain gauges are merged with precipitation estimates from several satellite-based algorithms and is very similar to that of GPCP.

From the IRI Data Library: Merged analysis

CPC MORPHing technique (CMORPH)

CMORPH is a product from NOAA-CPC and it produces global precipitation analyses at very high spatial (8km) and temporal (30 min) resolutions. This technique uses precipitation estimates that have been derived from low orbiter satellite microwave observations exclusively, and whose features are transported via spatial propagation information that is obtained entirely from geostationary satellite IR data. This method is extremely flexible such that any precipitation estimates from any microwave satellite source can be incorporated. Data is available starting from December 2002.

From the IRI Data Library: Morphing technique

Tropical Rainfall Measurement Mission (TRMM) Combination

TRMM is being flown by the National Aeronautics and Space Administration (NASA, U.S.) and the National Aeronautics and Japan Aerospace Exploration Agency (JAXA, Japan) to improve our quantitative knowledge of the 3-dimensional distribution of precipitation in the tropics. TRMM has a passive microwave radiometer, the first active space-borne Precipitation Radar, and a Visible-Infrared Scanner (VIRS), plus other instruments. Two of the products produced operationally in TRMM are the “TRMM and Other Satellites” precipitation estimate and the “TRMM and Other Sources” precipitation estimate. It optimally merges microwave and IR rain estimates to produce 3-hourly precipitation fields at quarter degree spatial resolution. Then the 3-hourly products are aggregated to monthly and merged with gauge data over land to produce the best-estimated monthly precipitation field. The data sets cover the period January 1998-present, with about a month’s delay.

From the IRI Data Library: Three-hourly precipitation estimates and Daily estimates

African Rainfall Estimation (RFE)

RFE is a product produced by NOAA-CPC specifically for Africa. The current version, RFE 2.0 (RFE2), started in January 2001. It replaced the previous version, RFE 1.0 (RFE1), which was operational from 1995 through 2000. RFE2 uses microwave estimates in addition to continuing the use of cloud top temperature and station rainfall data that formed the basis of RFE1. Meteosat geostationary satellite infrared data is acquired in 30-minute intervals, and areas depicting cloud top temperatures of less than 235Kare used to estimate convective rainfall. WMO Global Telecommunication System (GTS) data taken from ~1000 stations provide accurate rainfall totals, and are assumed to be the true rainfall near each station. RFE1 used an interpolation method to combine Meteosat and GTS data for daily precipitation estimates, and warm cloud information was included to obtain dekadal estimates. RFE2 obtains the final daily rainfall estimation using a two part merging process, then sums daily totals to produce dekadal estimates at about 10km spatial resolution.

From the IRI Data Library: Gridded precipitation estimates

African Rainfall Climatology (ARC)

ARC is also produced by NOAA-CPC at 10km spatial resolution daily. It is very similar to RFE except that 3-hourly TIR data is used instead of 30-minute and it does not include microwave observations. Its objective is to create 1982-present climatology of daily precipitation over African. Currently ARC data is available starting from 1995.