| The GEMpro for PRZM and GLEAMS employs the freely-available, USDA-NRCS stochastic weather model GEM (Generation of Weather Elements for Multiple Applications [http://www.wcc.nrcs.usda.gov/climate/gem.html]) and couples it to two commonly-used pesticide exposure models PRZM (EPA) and GLEAMS (USDA-NRCS). GEM simulates daily precipitation, temperature, wind speed, solar radiation, and dewpoint for a user-specified period of time. The GEMpro allows the user to select a site from hundreds of weather stations in the United States and then post-processes the GEM output to create weather input files for PRZM (EPA) and GLEAMS (USDA-NRCS). GEMpro may also be run iteratively to either produce summary statistics for building a distribution of weather data or to produce a series of stochastic weather data for probabilistic versions of GLEAMS or PRZM. The GEMpro provides several options for determining the fit of the simulated and observed weather data. Summary statistics (e.g., mean, maximum, and variation of annual and monthly precipitation, duration of wet and dry spells) of the observed data are presented while test statistics compare differences between the GEMpro output and the observed data for a particular station. A sensitivity analysis of the iterations of simulated weather data can also be conducted to determine the consistency of the GEMpro results. |
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