The following information is from the "README.txt" file for this data set found at ftp://ftp.cpc.ncep.noaa.gov/wd51yf/GHCN_CAMS/.
CPC Monthly Global Surface Air Temperature Data Set
at 0.5 degree from 1948-present
1. Description of the data
The unit for the temperature is (K), averaged monthly in GRIB format.
The data sets will be routinely updated around 8th of each month.
2. Raw spatical resolution & Coverage:
0.5 deg lat x 0.5 deg lon;
-89.75S -- 89.75N;
0.25E -> Eastward -> 0.25W (or 0.25E -> 359.75E);
from January 1948 to present;
The data set is also availabe at T126, T62 and 2.5x2.5 resolutions
in this directory.
3. Missing values:
9.999E+20
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4. Reading and using the data
A. GrADS data control files (___.ctl) in the same directory.
B. Use wgrib to manipulate, inventory, and decode GRIB files. See:
http://www.cpc.noaa.gov/products/wesley/wgrib.html.
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5. Reference:
Yun Fan and Huug van den Dool, 2008: A global monthly land surface air
temperature analysis for 1948-present. J. Geophys. Res., 113, D01103,
doi:10.1029/2007JD008470.
Yun Fan and Huug van den Dool, 2004: Climate Prediction Center global
monthly soil moisture data set at 0.5° resolution for 1948 to present.
J. Geophys. Res., VOL. 109, D10102, doi:10.1029/2003JD004345.