error: cannot locate 20CRv3/prate_daily.nc
Full metadata. The associated land/sea mask is available for some operations

Get grid points, average area or generate subset

Mask:	no mask mask7.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 monthly 10-daily 5-daily
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 absolute value percentile normal 1971-2000
Minimum:	% valid data
First apply:	-day running mean
Missing data:	ignore, climatology, trend, persistence.

Create a field with lower spatial resolution

Average over blocks of longitude and latitude grid cells

Please consider downloading this field from the authoritative site.
If you really want to get it here, 20CRv3 precipitation is available as a netcdf file (size MB).