Data Requirements for Estimation of Weather Generation Parameters

Weather generation models are needed to provide data for various agricultural and water managementapplications. The parameters required to make weather generation models functional must be derived from actualweather data to ensure that data generated are adequate representations of real weather data at a selected site. This studyexamined the stability of estimates of weather generation parameters relative to the length of record of actual data fromwhich the parameters were estimated. Stable estimates of the parameters for generating daily temperature were obtainedwith relatively short records of actual data. Precipitation generation parameters, however, required relatively longrecords to achieve stable estimates. The amount of data required to achieve a specific level of stability also depended onthe geographic location and the season of the year. In general, at least 10 years of data are needed for estimation oftemperature parameters and 20 or more years of data are needed for estimation of precipitation parameters.