GPCP Version 2.2 Combined Data Sets
X axis: whole world in 144 2.50° steps, first point at 1.25° E, last point at 358.75° E
Y axis: regular grid with 72 2.50° steps, first point at 88.75° S, last point at 88.75° N

Monthly data available from Jan1979 to Feb2015 ( 434 months)
Variable prcp (precipitation) in mm/day
Full metadata. The associated land/sea mask is available for some operations

Get grid points, average area or generate subset

Mask:	no mask mask3.txt   add a mask to the list
Latitude:	°N - °N
Longitude:	°E - °E
Boundaries:	halfway grid points interpolated
Make:	average max min set of grid points subset of the field
Demand at least:	% valid points in this region
Considering:	everything land points sea points show/hide more only land points only sea points not land points not sea points

Create a field with lower time resolution

New time scale:	annual (Jul-Jun) annual (Jan-Dec) biannual seasonal
New variable:	mean sd sum sum above sum below number min time of min max time of max first time last time of precipitation
Threshold:	no cut less than greater than mm/day percentile normal 1971-2000
Minimum:	% valid data
First apply:	-month running mean
Missing data:	ignore, climatology, trend, persistence.

Create a field with lower spatial resolution

Average over blocks of longitude and latitude grid cells

Construct a statistical forecast model from this field

Please consider downloading this field from the authoritative site.
If you really want to get it here, GPCP v2.2 precipitation is available as GrADS .ctl and gzipped .dat files (size 17.5605 MB)
Alternatively, you can generate a netCDF file of the same size.