Enhancement of forest fires over northeastern Japan due to atypical strong dry wind

Abstract

Characteristics of this wind are summarized as follows. 1) The surface wind speed remains weak during nighttime hours, even when the upper-level synoptic wind is strong. This is due to the nocturnal stable layer (NSL), which prevents the intrusion of the upper-level synoptic wind into the lowest levels near the surface. 2) Fluctuations in the surface wind speed are induced by variations in the incoming solar radiation due to the passage of small fair-weather cumulus clouds. 3) The onset of the atypical strong winds is related to the strength of the NSL. 4) Routine observations of the wind speed at a mountaintop having an altitude of 500-1000 m above sea level can be utilized to forecast the atypical strong wind, since the NSL does not form in such areas. -from Authors