Climate Moisture Index
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Interactive Map

Annual average climate moisture index (CMI, Willmott and Feddema, 1992) computed using the ratio of annual precipitation (P) to annual potential evapotranspiration, (PET).

Map description and dataset provided by: Water Systems Analysis Group, Complex System Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, USA

DescriptionClimate Moisture Index

This map shows the Climate Moisture Index (CMI) indicator for the globe on a 0.5 X 0.5 degree global grid. The CMI illustrates the relationship between plant water demand and available precipitation. The CMI indicator ranges from –1 to +1, with wet climates showing positive CMI, and dry climates negative CMI.

Interpretation

The CMI is an aggregate measure of potential water availability imposed solely by climate. Negative CMI values show potential evapotranspiration in excess of precipitation and thus the potential for climate-based water scarcity for resident populations. Areas with CMI values exceeding 0 generally represent humid or water abundant areas. Arid regions with very low rainfall show CMI values less than -0.5 where semi-arid regions have CMI values ranging from 0 to -0.5. These semi-arid transitional zones regions such as the southern flank of the Sahel in Africa are most vulnerable to impacts from climate change.

Source

The dataset for this map was provided by: Charles J. Vörösmarty, Water Systems Analysis Group, Complex System Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, USA

Background

This dataset was developed for the World Water Development Report II, Indicators for the World Water Assessment Program (http://wwdrii.sr.unh.edu/index.html) and in support of analysis outlined in Vörösmarty et al., 2005.

Citation

Please cite this map as: "GWSP Digital Water Atlas (2008). Map 40: Climate Moisture Index (V1.0). Available online at http://atlas.gwsp.org."

Contact Information

Charles J. Vörösmarty, Water Systems Analysis Group, Complex System Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH USA 03824, This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , Phone: +01.603.862.0850, Fax: +01.603.8