The GPCP provides a 2.5-degree latitude-longitude resolution pentad (5-day) mean precipitation data set, and I have calculated a pentad mean data set from the 1-degree latitude-longitude resolution daily GPCP data. I provide both data sets in netCDF format on this page.
A comparison of the Climate Prediction Center Merged Analysis of
Precipitation (CMAP) and GPCP merged precipitation datasets is given
Yin, X., A. Gruber, and P. Arkinc, 2004: Comparison of the GPCP and CMAP Merged Gauge-Satellite Monthly Precipitation Products for the Period 1979-2001. J. Hydromet., 5, 1207-1222.
The GPCP is managed by Robert Adler, and it is a component of the Global Energy and Water Cycle Experiment of the World Climate Research Program. GPCP is an ongoing project, and updates and new algorithms are always being developed, so users are advised to to check the NCDC GPCP WWW page and NASA Goddard Space Flight Center to see if there is a newer product that replaces this one. The updates of the data seem to lag reality by 2-3 months. I will not be updating the netCDF version of this data set until I have a need for updated data. Please send questions or comments about the product to Pingping Xie.