Statistical and geostatistical analysis of wind: A case study of direction statistics

To study the applicability of geostatistics for vector data, wind velocity data have been analyzed statistically and geostatistically. The study area consists of two districts, the mountainous Chubu and plain Kanto districts in central Japan. For the distribution of wind speeds, exponential distribution was fitted well in both districts. Temporal experimental variograms of wind speeds, directions and velocities suggest daily duration, and wind is stronger by day than by night. While some spatial experimental variogram of wind speeds are traditional spherical schemes showing clear nugget effects, sills and ranges whose values vary 50–130 km, other variograms are not traditional schemes illustrating flat or gradually increasing curves. If variograms of momentary wind speeds have no range an empirical variograms of temporally averaged wind speeds does not also show a range.