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Restrictions | Details | Caveats | File Naming | Citation | References | Original Source | Contact

CPC Merged Analysis of Precipitation (CMAP)

Brief Description:

  • Monthly and pentad global gridded precipitation means. It includes a standard and enhanced version (with NCEP Reanalysis) from 1979 to near the present. More Details...

Temporal Coverage:

  • Monthly values 1979/01 to 2014/12
  • Pentad values 1979/01 to 2014/06/25
  • Long term monthly means, derived from years 1979 to 2000.

Spatial Coverage:

  • 2.5 degree latitude x 2.5 degree longitude global grid (144x72).
  • 88.75N - 88.75S, 1.25E - 358.75E.


  • N/A

Update Schedule:

  • Irregular. Try to follow CPC

Download/Plot Data:

Variable Statistic Level Download File Create Plot/Subset
Precipitation Mean (Standard Monthly) ' ' plot
Precipitation Mean (Enhanced Monthly) ' ' plot
Precipitation Long Term Mean (Standard Monthly) ' ' plot
Precipitation Long Term Mean (Enhanced Monthly) ' ' plot
Precipitation Mean (Standard Pentad) ' ' plot
Precipitation Mean (Enhanced Pentad) ' ' plot

Usage Restrictions:

  • None

Detailed Description:

  • The monthly data set consists of two files containing monthly averaged precipitation rate values. Values are obtained from 5 kinds of satellite estimates (GPI,OPI,SSM/I scattering, SSM/I emission and MSU). The enhanced file also includes blended NCEP/NCAR Reanalysis Precipitation values. The other just includes the satellite estimates.
    Pentad data is also available.
  • This data set consists of monthly averaged precipitation rate values (mm/day). The data range is approximately 0 to 70mm/day. The pentad dataset consists of 73 pentads per year with the 12th pentad covering Feb 25-Mar 1 whether or not there is a leap year. The pentad starts on the date stored in the netCDF file.
  • Reading in GrADS: If you read the data in GrADS, it will assume the values are 5 days apart the entire time period including leap years. This isn't correct so you may get the wrong dates. To handle this in GrADS, you can use a ddf file rather than using sdfopen and set the calendar options to 365_day_calendar. Or, you can just use the "t" cvalues as each full year has 73 values starting Jan 1.


  • None

Related File Naming & Structure Information:

File Names:

  • /Datasets/cmap/enh/
  • /Datasets/cmap/std/
  • /Datasets/cmap/enh/

OpenDap File Names:


Dataset Format and Size:

  • PSD standard NetCDF 13 Mbyte file for each monthly file.
  • PSD standard NetCDF 80 Mbyte file for each pentad file.

Missing Data:

  • Missing data is flagged with a value of -9.96921e+36f. The enhanced version has no missing; the standard version does.


  • Xie, P., and P.A. Arkin, 1997: Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 2539 - 2558.
  • Please note: If you acquire CMAP Precipitation data products from PSD, we ask that you acknowledge us in your use of the data. This may be done by including text such as CMAP Precipitation data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSD to justify keeping the CMAP Precipitation data set freely available online in the future. Thank you!


  • Huffman, G. J. and co-authors, 1997: The Global Precipitation Climatology Project (GPCP) combined data set. Bull. Amer. Meteor. Soc., 78, 5-20.
  • Reynolds, R. W., 1988: A real-time global sea surface temperature analysis. J. Climate, 1, 75-86.
  • Spencer, R. W., 1993: Global oceanic precipitation from the MSU during 1979-91 and comparisons to other climatologies. J. Climate, 6, 1301-1326.
  • Xie P., and P. A. Arkin, 1997: Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Amer. Meteor. Soc., 78, 2539-2558.

Original Source:


  • Physical Sciences Division: Data Management
    325 Broadway
    Boulder, CO 80305-3328