Intra-seasonal and interannual variations in snowfall and rainfall during winter in Rikubetsu, inland Hokkaido, Japan

Global warming is likely to increase precipitation and the relative proportion of rainfall to precipitation. Since relatively few continuous and independent observations of snowfall and rainfall have been conducted worldwide, it is difficult to clarify the likelihood of future changes in the proportion of snow versus rainfall. Low-cost disdrometers, which have become more ubiquitous in recent years, can record snowfall and rainfall separately based on the characteristics of the precipitation particles. In this study, snowfall and rainfall amounts were investigated using disdrometer measurements for the winters from 2013 to 2023 in Rikubetsu (43.5°N, 143.8°E), Hokkaido, Japan. It represents the current status on snowfall in one of the southernmost regions of the Arctic. The results show that the total winter precipitation in each year ranged from 101.9 to 399.6 mm. Rainfall ranged from 5.9 to 80.2 mm, and therefore accounted for 17% of the total precipitation, 96% of which occurred in December and March. Rainfall accounted for 2% in January and February, and 27% in December and March, respectively. Large snowfall and rainfall events contributed significantly to total winter precipitation, and these events were associated with rising temperatures associated with synoptic-scale disturbances. Snowfall occurred when temperatures were below freezing after warming, and rainfall occurred when temperatures were above freezing. It is considered that future changes in temperatures during synopticscale disturbances will play a key role in the amount of rainfall in Rikubetsu as the climate changes.