readme_gis.txt
6/1/00

Note:  this data is available in two formats.  The original ASCII formatted 
output and ASCII GRID format which can be imported directly into
ARC/INFO GIS software.  This document describes the latter.

CRU05 1901-1996 0.5o Latitude/Longitude Monthly Climate Data
23 August 1998

Global Data

Variables                  Directory           Units
Precipitation              pre                 mm
Wet day frequency          rd0                 days
Mean temperature           tmp                 degC*10
Diurnal temperature range  dtr                 degC*10
Vapour pressure            vap                 hPa*10
Cloud cover                cld                 oktas*10


Format - ASCII Grid format (for ArcInfo)
         The first 5 rows include the header information and NODATA values
         are set to -9999.
Projection - Data not projected/Geographic (lat/long)
Number of Columns - 720
Number of Rows - 360
Cellsize - .5

Each variable directory (pre, rd0, tmp...) contains a directory for each year
represented by the data (1901d, 1902d...).  Each of these directories contains
12 zipped files representing months of the year (numbered 1-12).  Use gzip to
uncompress the files.  Use the ASCIIGRID command in ArcInfo or GRID to import 
the grids.

    ARC:  ASCIIGRID <in_ascii_file> <out_grid> {INT | FLOAT}
    GRID: <out_grid> = ASCIIGRID (<in_ascii_file>, {INT | FLOAT})

The original data was subsetted and reformatted into monthly grids using perl 
script and Arc Macro Language (AML) programming.  Specifically, perl script was
used to reformat the header information to the asciigrid file format and to
parse the yearly data into monthly grids.  AML was used to read the data into
ArcInfo, to FLIP the grids, and to export the grids to asciigrid format.