NARCCAP Data Overview

NARCCAP data is stored in CF-compliant NetCDF format. Filenames are of the form VariableName_ModelName_Time.nc.

VariableName is the IPCC/CF-convention Variable Name as listed in the data tables
ModelName is the 4-character RCM identifier
Time is the starting time of the file, in the form YearMonthDayHour.

Each file contains data for a single variable. For 3-D data, a file covers one month. For 2-D data, a file covers 5 years, ending in a year that ends in 0 or 5. (Files covering the beginning and ending of the run may not contain a full five years of data.)

So, for example, tas_RCM3_1981010103.nc contains data for variable tas from the RegCM3 regional model starting at 03 GMT on January 1st, 1981 and ending at 00 GMT on January 1st, 1985. All times are UTC (Universal Coordinated Time) or, equivalently, GMT (Greenwich Mean Time).

Useful Links

model-info.html -- Information about the models.
data-tables.html -- How the variables are grouped
http://cf-pcmdi.llnl.gov/documents/cf-conventions -- The CF Metadata Standard
http://cf-pcmdi.llnl.gov/documents/cf-standard-names -- The CF Standard Name Table

NetCDF

NetCDF is a data format for storing array-oriented scientific data, particularly geophysical data. It is highly portable, widely-understood, and has built-in metadata that makes the files self-describing.

The main data array has associated coodinate arrays, xc, yc, and time, for each of its dimensions. Time is an unlimited or record dimension (important for some tools). Each variable in a NetCDF file can have attributes associated with it.

NetCDF Header

Here is an example of the headers for a NetCDF file: pr_WRFP_1979090103.nc.head.txt -- produced by ncdump -h pr_WRFP_1979090103.nc

Useful Links

http://www.unidata.ucar.edu/software/netcdf/ -- The NetCDF homepage