TITLE OF THE DATA SET

A Comprehensive Precipitation Data Set for Global Land Areas.


DATA CONTRIBUTORS

Jon K. Eischeid
Henry F. Diaz
CIRES, University of Colorado
and Environmental Research Laboratories
NOAA
Boulder, Colorado

Raymond S. Bradley
University of Massachusetts
Amherst, Massachusetts

Philip D. Jones
Climatic Research Unit
University of East Anglia
Norwich, United Kingdom

DOI: 10.3334/CDIAC/cli.tr051

SOURCE AND SCOPE OF THE DATA

     An expanded and updated compilation of long-term station
precipitation data, together with a new set of gridded monthly mean
fields for global land areas are provided in this subdirectory.  This
data set contains 5328 station records of monthly total precipitation,
covering the period from the mid 1800s to the late 1980s.  The
station data were individually tested and visually inspected for
the presence of spurious trends, jumps and other measurement
biases.  The quality control procedure which was used to check the
station records for nonclimatic discontinuities and other biases
is detailed in the report that accompanies these data files.  Some 
of the problems which typically contribute to potential inhomogeneities 
in precipitation records are also described in the accompanying report.
     The station data were interpolated onto a 4 degree latitude by 
5 degree longitude uniform grid. Comparisons of these data with two 
other global scale precipitation climatologies showed good agreement
among the three global scale climatologies over the common areas in 
each set. Three different indices of long-term precipitation variations
over the global land areas all indicate a general increase of annual 
precipitation since the 1940s, although a decline is evident over the 
last decade.  There is some indication that the last few decades of 
the 19th century may have been as wet as the recent ones.  An 
interesting feature of this study is the presence of relatively large 
differences in seasonal trends, with March-May and September-November 
becoming wetter in the last few decades.  The December-February and 
June-August seasons exhibit smaller overall trends, although the 
northern winter season does exhibit large decadal-scale fluctuations.

DATA FORMAT

Four files are provided in this subdirectory (TR051) including this
descriptive file (tr051.des), one data file containing the seasonal
precipitation anomalies (in mm) interpolated to a 4 degree by
5 degree latitude-longitude grid for the period 1851-1989
precip.grd), one data file containing the total monthly precipitation 
records for the 5328 station used to compile the gridded data set 
(station.dat), and a file that provides an inventory of the surface 
stations (station.inv).  

The file (precip.grd) that contains the gridded seasonal precipitation 
anomalies may be read in the following manner:

       PROGRAM READ
       REAL DATA(72,38)
       DO 100 IY=1851,1989
        DO 99 IS=1,5
        READ(1,'(I4,I2)')IYEAR,ISEAS
        READ(1,'(12F8.2)')((DATA(J,K),J=1,72,K=1,38)

where:

ISEAS = 1 = DJF
        2 = MAM
        3 = JJA
        4 = SON
        5 = Annual

J     = 1 = 0 degrees
        2 = 5 degrees E
        3 = 10 degrees E
        . = .
        . = .
        . = .
        . = .
       72 = 5 degress W

K     = 1 = 62 degrees S
        2 = 58 degrees S
        3 = 54 degrees S
        . = .
        . = .
        . = .
        . = .
       38 = 86 degrees N

All missing values are denoted by -9999.99.

The format of the file (station.dat) that contains the surface station 
records is as follows:

1) Header record (record length = 68 characters)

  GHCN/DOE id#    Latitude      Longitude     Elevation    Station Name
    9999999999      9999           99999        99999        (33 char.)

  Begin yr        End yr        id
    9999           9999          9999999

  GHCN/DOE id# (I10): 

   contains

     WMO region (I1)
     WMO country code (I2)
     WMO # (I6)
     Flag (I1)
       Flag=0 if a standard WMO station 
       Flag=1 if WMO # has been assigned, but is not listed in WMO official
              station listing (i.e., it indicates that it is a 'pseudo-WMO'
              id number).

  Latitude (I4): tenths of a degree, south latitude is negative
  Longitude (I5): tenths of a degree, east longitude is negative
  Elevation (I5): meters
  Station name (A33): station name and country
  Begin yr (I4): initial year of record
  End yr (I4): final year of record
  id (I7 or A7): unique station code assigned to a particular station by the
                 data source (country organization furnishing the data). This
                 information is not available for all stations.

Example of one header record:

6010100100 710   84    9jan mayen                        19221989

2) Data records (one logical record per year)

 year       12 monthly values
 9999       12 x 999999

 year (I4)
 data (12I6): in tenths of millimeters, missing values are negative


REFERENCES

Eischeid, J.K., H.F. Diaz, R.S, Bradley, and P.D. Jones. 1991. A comprehensive
   precipitation data set for global land areas. DOE/ER-69017T-H1, TR051,
   United States Department of Energy, Carbon Dioxide Research Program,
   Washington, D.C. doi: 10.3334/CDIAC/cli.tr051