Non-weibull behavior observed in a model-generated global surface wind field frequency distribution

The frequency distribution of the surface wind speeds at each 4.5⁰ x 7.5⁰ latitude-longitude grid point produced by the National Center for Atmospheric Research community climate model is examined. A modified Kolmogorov-Smirnov (KS) test was used to ascertain the extent of Weibull behavior for perpetual January and July model runs. The modified KS test has been applied to 400 days of both perpetual January and July model runs using a 0.5-day time sample. A global map of the KS statistic for each of the January and July control runs has been generated. These maps are presented for both the ocean and land wind fields. For the January oceanic winds, 29.2% of the frequency distributions were non-Weibull at the 95% confidence level. Over land, 35.4% of the wind speed frequency distributions were judged to be non-Weibull. For the July wind speed data, 32.7% of the ocean data sets were judged to be non-Weibull, while for winds over land, 30.2% were found to be non-Weibull. Large areas of Eurasia experience non-Weibull behavior during the January run. The main oceanic latitudinal zones associated with a non-Weibull character are from 5 ø to 30 ø in each hemisphere, a feature that is most evident in the July run. The monsoonal winds over the Indian Ocean are almost entirely Weibull. The non-Weibull character of surface wind field frequency distributions may explain, in part, the apparent inability of some surface wind data sets to drive an ocean circulation model through inexact wind forcing.