The climatology of cold-air damming in the Kanto Plain, Japan

The climatological characteristics of cold-air damming (CAD) were statistically investigated on the Kanto Plain throughout the year. We detected 397 CAD events from 1991 to 2020 using hourly surface observation data from the Japan Meteorological Agency. The statistical analyses revealed the following characteristics: (1) CAD is most frequent in autumn followed by spring; (2) strong CAD is more frequent in the cold season than in the warm season; (3) The long-term trend in CAD frequency is not obvious; (4) 53% of the events finish in 12 h or less, and 17% of them continue for 24 h or more. CAD with precipitation tended to be stronger than that without precipitation, and the latter was more frequent in the nighttime than in the daytime, indicating the contribution of diabatic processes to the development of CAD. Analysis of synoptic fields in CAD cases using long-term reanalysis data revealed six patterns that differed in the intensity and position of surface highs and lows, corresponding to the typical seasonal sea level pressure fields.