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ARS Home » Pacific West Area » Boise, Idaho » Northwest Watershed Research Center » Research » Publications at this Location » Publication #96298
Title: GEM (GENERATION OF WEATHER ELEMENTS FOR MULTIPLE APPLICATIONS): ITS APPLICATION IN AREAS OF COMPLEX TERRAIN

Author
item Hanson, Clayton
item JOHNSON, GREGORY - USDA-NRCS

Submitted to: International Association of Scientific Hydrology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: To address the need for readily-available climate data, the stochastic simulation model GEM (Generation of Weather Elements for Multiple applications) is being developed that delivers a statistically-representative, time series of daily weather. GEM provides easy access to precipitation probabilities or simulated daily weather data for as many months or years as needed for a location within the contiguous United States. Daily precipitation, maximum and minimum air temperatures, solar radiation, dew-point temperature and wind speed can be simulated. Comparisons between historical and simulated weather records for three climatological sites on the Reynolds Creek Experimental Watershed in climatological sites on the Reynolds Creek Experimental Watershed in southwest Idaho, showed that the simulated number of wet days and amounts of precipitation per wet day were representative of historical values. Simulated mean monthly maximum and minimum air temperatures were within 2.9 degrees Celsius of the observed values, while simulated mean annual air temperatures were within 1 degree Celsius of historical values. Simulated mean monthly solar radiation varied as much as 15 percent from historical values but most were within 10 percent. Generated mean monthly and annual wind speeds were nearly all less than 0.56 m/s different from observed values.

Technical Abstract: The stochastic climate simulation model "Generation of Weather Elements for Multiple Applications" (GEM) has been modified to simultaneously generate mean daily dew-point temperature and wind speed in addition to other weather elements. Comparisons between historical and simulated weather records for three climatological sites on the Reynolds Creek Experimental Watershed in southwest Idaho, USA, showed that the simulated number of wet days and amounts of precipitation per wet day were representative of historical values. Simulated mean monthly maximum and minimum air temperatures were within 2.9 degrees Celcius of the observed values, while simulated mean annual air temperatures were within 1 degree Celcius of historical values. Simulated mean monthly solar radiation varied as much as 15 percent from historical values but most were within 10 percent. Generated mean monthly and annual wind speeds were nearly all less than 0.5 m/s different from observed values.