This dataset contains Version 3.2 of The Global Precipitation Climatology Project (GPCP) Satellite-Gauge (SG) Combined Precipitation Data Set at monthly resolution (GPCPMON). The variables included are combined SG precipitation, combined SG precipitation random error, multi-satellite precipitation, probability of liquid phase, wind-loss adjusted gauge precipitation, satellite source index, gauge relative weighing, and quality index.

As the follow-on to the GPCP Version 2.X products, GPCP Version 3 (GPCP V3.2) seeks to continue the long, homogeneous precipitation record using modern merging techniques and input data sets. The GPCP V3 suite currently consists of the 0.5-degree Monthly and Daily products. A follow-on 0.1-degree 3-hourly product is expected. All GPCP V3 products are constructed to be internally consistent. The Monthly product spans 1983 to the present, with roughly quarterly updates.

Inputs consist of the Goddard Profiling Algorithm (GPROF) applied to the 6 AM/PM (local solar time) Special Sensor Microwave Imager / Special Sensor Microwave Imager-Sounder (SSMI/SSMIS) passive microwave (PMW) orbit files that are used to calibrate the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN-CDR) infrared (IR) based precipitation in the span 60 degrees N-S, which are in turn calibrated to the monthly 2.5-degree Microwave Emission brightness Temperature Histograms (METH) product computed from the same SSMI/SSMIS data. The METH-GPROF-adjusted PERSIANN-CDR IR estimates are then climatologically adjusted to the blended Tropical Combined Climatology (TCC) at low latitudes and Merged CloudSat, Tropical Rainfall Measuring Mission (TRMM), and GPM (MCTG) climatology at higher latitudes. These climatologies are computed from shorter-term, but higher-quality precipitation datasets that are considered to provide the best global climatology of precipitation. Outside of 58 degrees N-S, estimates computed from Television-Infrared Operational Satellite (TIROS) Operational Vertical Sounder / Advanced Infrared Sounder (TOVS/AIRS) data, adjusted climatologically to the MCTG, are used. The PERSIANN-CDR / TOVS/AIRS estimates are then merged in the region between 35 degrees N-S and 58 degrees N-S, and this multi-satellite product is then merged with Global Precipitation Climatology Centre (GPCC) gauge analyses over land to obtain the complete Monthly product. In addition to the merged precipitation field, random error, Quality Index, and probability of liquid phase estimates are provided.

GPCP Version 3 was initiated under a NASA Making Earth Science Data Records for Use in Research Environments (MEaSUREs) program (PI: George Huffman, NASA GSFC) and is now being upgraded under a current NASA MEaSUREs project (PI: Ali Behrangi, University of Arizona). The GPCP is computed as a contribution to the World Climate Research Program (WCRP) and Global Water and Energy Exchange (GEWEX) activity and is part of the array of data sets describing the water and energy cycles of the planet. Prior versions of the GPCP analysis have been produced by a consortium of individual scientists at various government and university institutions and most recently as part of the NOAA Climate Data Record (CDR) Program. The current GPCP Monthly SG product described here blends precipitation estimates from polar-orbit PMW imagers (SSMI, SSMIS), polar orbit IR sounders (TOVS, AIRS), and geostationary IR imagers (GOES, MeteoSat, GMS, MTSat, and Himawari); and then combines in Global Precipitation Climatology Centre (GPCC) precipitation gauge analyses, the Tropical Combined Climatology (TCC); and the Merged CloudSat, TRMM, and GPM (MCTG) climatology products.

For more information, see the GPCPMON official site at NASA GES DISC.