The WMO maintains a list of station numbers for meteorological stations to facilitate international data exchange. Unfortunately, many countries also maintain their own numbering systems and station lists for a range of operational and historical reasons. Occasionally, stations do not have a matching WMO number or have inconsistent WMO numbers.
The numbers we use are listed in numerical order up to station number 988360. Up to this point, the numbers ending in zeroes are generally the WMO number (*10) in use for that station in the mid-1980s. Numbers not ending in a zero have generally been assigned by CRU or may have originated from other sources. Stations that are listed after number 988360 are stations for which CRU has assigned numbers, mostly beginning with 72 (so using spare country numbers not officially used by WMO) to 75 (corresponding to stations in the United States). Some WMO IDs have been updated in the 2000s.
Latitude of the station in degrees and tenths (so 712 is 71.2 degrees N). Positive values are degrees and tenths North, with negative values for the Southern Hemisphere. These latitudes refer to the locations of the stations as defined in the mid-1980s, although some may have been updated in the 2000s. There are a number of reasons why site locations (both position and height) may have apparently changed (when, in fact, there was no site move) including, for example, more accurate mapping of locations using GPS.
Longitude of the station in degrees and tenths (as with the latitude). Positive values are West and negative East. These longitudes refer to the locations of the stations as defined in the mid-1980s, although some may have been updated in the 2000s.
Station elevation (in metres) as defined in the mid-1980s, although some may have been updated in the 2000s. Unknown elevations are coded as -999. A number of sites within the former USSR have zero elevation. This is incorrect, but this is a field that is not used by the gridding program (see later) and therefore the elevation (whether known, unknown or incorrect) does not affect the gridded data set.
The final field is the station name and the country. This is largely as defined in the mid-1980s, with some being updated in the 2000s. This field is also not used within the gridding. Some country names are missing, and many have not been updated for country name changes; for example the break-up of the countries of the former USSR and Yugoslavia.
Brohan, P., Kennedy, J., Harris, I., Tett, S.F.B. and Jones, P.D., 2006:
Uncertainty estimates in regional and global observed temperature changes: a new dataset from 1850.
J. Geophys. Res. 111, D12106, doi:10.1029/2005JD006548.