Global Climate Maps from FAOEntry ID: FAO_CLIMATE_MAPS
Abstract: The FAO global climate maps are based on data for mean monthly values of
temperature, precipitation and cloudiness prepared in 1991 by R. Leemans and W.
Cramer and published by the International Institute for Applied Systems
Analysis (IIASA). The IIASA data correspond to an imaginary "net" covering the
Earth's surface with a mesh size of 0.5 degrees. This is equivalent to about 60
km - an area of ... about 3,600 sq. km - at the equator.
Monthly climatic data for each cell in the net are provided by weather stations
and consist of an average, or "normal", value of monthly climate elements.
Using spatial extrapolation, a value is computed for each cell based on the
neighbouring station values.
The IIASA database includes three key climatic elements: average monthly
rainfall total, average monthly temperature, and monthly average sunshine. For
each of the stations used in the gridding exercise, data have been assembled
over a long time period - usually between 1961 and 1990 - and then averaged.
Annual totals for rainfall, and the averages for temperature and sunshine, were
derived from the monthly values.
Two products derived by the FAO Agrometeorology Group from the IIASA data sets
are a "climate classification" according to Koeppen, and "Potential biomass"
according to Lieth.
The most widely used system of climate classification is that of the German
climatologist Koeppen (1936) - virtually all more recent classifications are
refinements or variants of the "Koeppen system". The classification is based on
monthly rainfall and temperatures, including the following five inputs:
- Average monthly temperature of the warmest month
- Average monthly temperature of the coldest month
- Average thermal amplitude between the coldest and warmest months
- Number of months with temperature exceeding 10¡C
- Winter and summer rains
The Koeppen system assigns codes to the main climates: Tropical (A), Dry (B),
Temperate (C), Cold (D) and Polar (E):
Potential biomass is the amount of plant biomass that can be accumulated in one
year under the assumption of ideal conditions prevailing for photosynthesis,
i.e. absorption of solar energy by plants and storage of the energy as plant
material. The map given below uses one of the earliest methods, developed by H.
Lieth and published in 1972.
FAO's Environment and Natural Resources Service (SDRN) is making the global
climate data base available as geo-referenced digital images and maps. The data
are in Image Display and Analysis (IDA) format, DOS-based public domain
software developed jointly by FAO and USAID's Famine Early Warning System
(FEWS) for displaying, processing and analysing satellite images.
The data can be analysed using WinDisp (view sample screen), a Windows-based
successor to IDA that was developed with funding from the European Union as
part of the FAO Global Information and Early Warning System (GIEWS) Workstation
Project. The SADC Food Security Technical Unit, FAO-ARTEMIS, USAID-FEWS, the
USGS EROS Data Center and the US Forest Service have contributed funds to add
additional analytical features to WinDisp.
Data Set Citation
Dataset Originator/Creator: FAO Agrometeorology Group
Dataset Title: Global Climate Maps
Dataset Release Place: Rome, Italy
Dataset Publisher: FAO/SDOnline Resource: http://www.fao.org/sd/EIdirect/climate/EIsp0002.htm
Start Date: 1961-01-01Stop Date: 1990-12-31
Latitude Resolution: 0.5 degree
Longitude Resolution: 0.5 degree
ATMOSPHERE > ATMOSPHERIC TEMPERATURE > AIR TEMPERATURE
ATMOSPHERE > PRECIPITATION > PRECIPITATION AMOUNT
ATMOSPHERE > PRECIPITATION > RAIN > RAINFALL
ATMOSPHERE > ATMOSPHERIC RADIATION > SUNSHINE > SUNSHINE DURATION
BIOSPHERE > ECOLOGICAL DYNAMICS > ECOSYSTEM FUNCTIONS > BIOMASS DYNAMICS > BIOMASS POTENTIAL
Data Set Progress
Distribution Media: online, www
Leemans, R. and Cramer, W., 1991. "The IIASA database for mean monthly values of temperature, precipitation and cloudiness on a global terrestrial grid". Research Report RR-91-18. November 1991. International Institute of Applied Systems Analyses, Laxenburg, pp. 61.
Lieth, H., 1972. "Modelling the primary productivity of the earth. Nature and resources", UNESCO, VIII, 2:5-10.
Creation and Review Dates
DIF Creation Date: 2004-08-05
Last DIF Revision Date: 2004-08-05