Development of a Nocturnal Temperature Inversion in a Small Basin Associated with Leaf Area Ratio Changes on the Mountain Slopes in Central Japan

Nocturnal temperature inversion (NTI) is an important factor characterizing the local climate in mountainous areas. In central Japan, most of mountain slopes are covered by forests, but effects their leaf expansion/fall on NTI variations basins have not been clarified. According to a three-year area index (LAI) observation mixed forest Sugadaira Highland (1320 m a.s.l.), Nagano Prefecture, we identified weakening associated with expansion and strengthening after fall small basin. Using digital elevation land-cover data, defined distribution deciduous forests catchment nocturnal cold air drainage. The estimated timings at scale based effective cumulative almost coincided changes. Micrometeorology observations showed that floor downslope winds adjacent grassland strengthened during dormant (leafless) season nighttime when radiative cooling strong. Calm clear nights were chosen spring summer growing for 22 30 nights, respectively. heat loss cold-air pool development was estimated, converted storage flux 3.8 W m−2 more average than season, it less previous studies (several 10 m−2), indicating increase could cancel weaken gravity currents floor.