UNEP/GRID Documentation Summary for Data Sets:
Africa Climate from FAO/Agrhymet Network & ESRI


These three African climate data sets originate from manuscripts that
were received by ESRI from FAO, as part of work performed under a UNEP
contract to a) construct a World and Africa GIS Database, and b) conduct
a Desertification and Mapping project, both on behalf of UNEP and FAO.
The source climate maps were prepared directly from original hand-drawn
maps, provided by FAO on stable basemap copies at a 1:5,000,000 scale.
Isolines plotted on the FAO/AGS basemaps were then manually digitized by
ESRI.  The final products were later rasterized at UNEP/GRID-Geneva for
the African Database at spatial resolutions of 30 seconds and 2 minutes
latitude/longitude (approx. one and four kilometers, respectively).

Precipitation is "average annual", and is expressed in terms of
millimeters (mm.) per year; Average Days of Precipitation ("Wet Days")
is number of days per year; and Average Windspeed is expressed in
terms of meters per second (note that this is not maximum windspeed,
nor is there any directional content included in this data set).
It is GRID's assumption that the definition of a "wet day"
is one in which enough precipitation occurred on a given day so as
to be recordable by a gauging station at a particular location.

The three FAO/Agrhymet Africa data files all cover the entire African
continent at a spatial resolution of two minutes (120 seconds) of
latitude/longitude, or approximately 3.7 kilometers.  The data files
consist of 2191 rows (lines, records) by 2161 columns (elements, pixels,
samples) each.  Their common upper-left or northwest corner origin is
38 degrees, 0 minutes and 45 seconds North latitude (38d 00' 45" N), and
-20 degrees, 1 minute and 15 seconds West longitude (-20d 01' 15" W);
and they extend to -35 degrees, 1 minute and 15 seconds South latitude
(-35d 01' 15" S), and 52 degrees, 0 minutes and 45 seconds East
longitude (52d 00' 45" E) at their terminal point in the lower-right
or southeast corner.  Each data file comprises 4.74 Megabytes.

The proper reference for these data sets is "Final Report: UNEP/FAO
World and Africa GIS Data Base; December 1984."  Prepared by ESRI -
Environmental Systems Research Institute, 380 New York Street,
Redlands, CA., USA 92373 (one full volume including appendices).
The source to credit is the FAO/UNEP Desertification and Mapping
Project, as rasterized by UNEP/GRID (date of process 1986).

Files:
africa_rain.bil - Image File
africa_rain.hdr - World File for Image Display
africa_rain.bwl - Header File for Image Display
africa_rain.shp - ESRI GIS Shapefile
africa_rain.dbf - DBF File (part of Shapefile)
africa_rain.shx - SHX File (part of Shapefile)
africa_rain.avl - Legend for Shapefile
africa_rain & info folder


UNEP/GRID Legend for Data Set:
Mean Annual Rainfall (Africa; FAO/Agrymet)

Class #   Millimeters per annum
-------   ---------------------
   1         0 - 50
   2        51 - 100
   3       101 - 150
   4       101 - 200
   5       151 - 200
   6       201 - 250
   7       201 - 300
   8       201 - 400
   9       251 - 300
  10       251 - 400
  11       301 - 350
  12       301 - 400
  13       351 - 400
  14       401 - 450
  15       401 - 500
  16       401 - 600
  17       451 - 500
  18       451 - 550
  19       501 - 550
  20       501 - 600
  21       551 - 600
  22       601 - 700
  23       601 - 800
  24       601 - 1000
  25       701 - 800
  26       801 - 900
  27       801 - 1000
  28       901 - 1000
  29      1001 - 1500
  30      1501 - 2000
  31      2001 - 3000
  32           > 3000

UNEP/GRID Legend for Data Set:
Number of Wet Days (Africa; FAO/Agrymet)

Class #   No. of Wet Days/Year
-------   --------------------
   1                0
   2              1 - 20
   3             21 - 40
   4             41 - 60
   5             61 - 80
   6             61 - 100
   7             61 - 120
   8             81 - 100
   9             81 - 120
  10            101 - 120
  11                > 120

UNEP/GRID Legend for Data Set:
Mean Annual Wind Velocity (Africa; FAO/Agrymet)

Class #   Windspeed in meters/second
-------   --------------------------
   1       0.0 - 0.5
   2       0.5 - 1.0
   3       1.0 - 1.5
   4       1.5 - 2.0
   5       2.0 - 2.5
   6       2.5 - 3.0
   7       3.0 - 3.5
   8       3.5 - 4.0
   9       4.0 - 4.5
  10       4.5 - 5.0
  11       5.0 - 5.5
  12       5.5 - 6.0
  13           > 6.0

