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National Water and Climate Center


Weather Generator Technology (GEM)

For many applications, users need a continuous time stream of weather data, typically to be used as input to a computer model of some process of interest, such as water or wind erosion. A weather generator is a statistical model that can be used for this purpose. Presented here is brief information about one such stochastic weather simulation model, or weather generator technology known as the GEM (Generation of weather Elements for Multiple applications) model. This is an on-going research and development project, as well, in joint partnership between the NRCS National Water and Climate Center and the USDA Agricultural Research Service (ARS).


GEM delivers a time series (data stream) of daily weather data (precipitation, maximum and minimum temperature, solar radiation, dewpoint and wind speed). When you run the model you can generate as many years of simulated weather as desired, for any location in the continental U.S.

Stochastic Climate Simulation Models diagram
How GEM Functions.

Further Information

For more information, please contact:

Dr. Greg Johnson
Leader, Air Quality and Atmospheric Change Team
USDA-NRCS West National Technology Support Center
1201 NE Lloyd Blvd., Suite 1000
Portland OR 97232-1274
(503)273-2424 Fax: (503)273-2401
email: greg,johnson@por.usda.gov