A Study on Climatological Aspects of Winds in Japan. Part I: Mean Wind Fields and Annual Variations of Winds

Abstract

Using the winds in Japan as an example, the validity of the vectorial treatment of the surface wind in climatological investigations has been demonstrated, and the expressions for climatological mean and variability of the wind have been reviewed. The annual resultant surface winds tend to be westerly at latitudes higher than 30° and easterly at lower latitudes. At lower latitudes, the mean surface winds and the mean 850 mb winds are almost opposite to each other in direction at times. Climatological mean wind directions according to different definitions have been investigated for the surface wind. The means of wind direction agree with the directions of the vector mean wind within 30° where the magnitudes of the vector mean wind are larger than 1.5 m s?1. The relationships between the two measures of the constancy of the wind are investigated.