The Global Precipitation Climatology Project (GPCP) consists of monthly satellite-gauge and associated precipitation error estimates and covers the period January 1979 to the present. The general approach is to combine the precipitation information available from each of several satellite and in situ sources into a final merged product, taking advantage of the strengths of each data type: passive Microwave estimates are based on SSMI/SSMIS data; infrared precipitation estimates are included, using GOES data and POES data; as well as other low earth orbit data and insitu observations. Data are provided on a 2.5 degree grid.