[thredds] use of thredds data server

Dear all,

Thanks for the very useful tool NetcdfSubset. http://www.ncdc.noaa.gov/thredds/ncss/grid/gpcp_agg/dataset.html I try to use it to extract monthly mean GPCP precipitation, for years from 1991 to 2010, in netcdf format. I obtain a file which contains 624 time steps. I've expected 240: 12 months * 20 years. I think I obtain first the 240 time steps I've required in the file, then the entire archive from 1979 to 2010 (384 time steps more). Can you explain me this think? Is it possible to extract only the 240 time steps?
Thank you very much.

Isabelle Charon (Meteo-France, Frebch meteorology service)