Behavior of Winds in the Lowest 200 m in Central Tsukuba Science City

Abstract

A meteorological observation tower at Tsukuba Science City is equipped with mean wind, temperature and humidity sensors, together with instruments for the measurement of their short period fluctuations at seven levels (including the top of the tower) ranging from 10 m to 213 m above the base of the tower. The general statistical properties of wind data for one year are discussed in this paper together with the tower facilities including the data acquisition system. The annual arithmetic mean wind speeds increase from 3.14 m/s at the 25 m level to 6.09 m/s at the top level. The annual mean wind speed at the 25 m level is highest during the daytime and one at the 213 m level at night. Monthly relative frequency distribution of wind speed can be well simulated with Weibull distribution. Annual relative frequency of wind direction has three clear peaks, which are very similar to the climatological data obtained at the Tateno Aerological Observatory near the Meteorological Research Institute. The characteristics of vector wind speed are examined and the monthly mean profiles from May to September seem to be explained by the geostrophic wind. The power spectra of wind speed in summer and fall have a remarkable peak of daily cycle and a relatively large peak with 3-4 days period in winter and spring.