Abstract
Using data at 724 stations for 12 years in Japan, the climatological characteristics of diurnal variation in surface wind speed were examined. Wind speed reaches a maximum in early afternoon at most sites. The relative amplitude with respect to the daily mean is larger for winds in lower percentiles, while the 99.9_th percentile winds also have a peak in early afternoon as an average for all stations. The amplitude and phase of the first harmonics of temperature and wind speed are positively correlated among stations, but their variability is larger for wind speed than for temperature. The amplitude and phase of wind speed are correlated with geographical factors such as the percentage of water surface, topographic convexity, and population density, with urban stations tending to show later phase. The amplitude of diurnal variation is small at some stations where nighttime wind speed is comparable to that in the daytime, possibly due to dominant mountain breezes.
