Impacts of climate change on heavy wet snowfall in Japan

Wet snow is a primary cause of atmospheric icing, which can lead to severe damage to power towers and lines, resulting in electrical breakdowns and blackouts. This study investigates the influence of climate change on heavy wet snowfall events in Japan by using climate projections obtained from the database for policy decision-making for future climate change (d4PDF). The projected future climate in the regional model simulations shows nonuniform spatial distribution of wet snowfall. The increases in the risk of extreme wet snowfall are found over northern part of Japan Alps (mountainous regions in central Japan) and Hokkaido (northern part of Japan). Self-organizing maps (SOMs) are applied using the surface atmospheric circulation to explore the weather patterns (WPs) associated with changes in heavy wet snowfall. The SOMs show that some WPs have a significant effect on the magnitude, frequency, and location of heavy wet snowfall in Japan. Additionally, the impact of climate forcing on WPs associated with heavy wet snowfall is evaluated to understand the spatially heterogeneous changes in wet snowfall. The SOM analysis results suggest that the future changes in spatially heterogeneous extreme wet snowfall can be attributed to differences in WP responses to climate change. These differences can be attributed to the future variations in the region of the atmospheric layer at temperatures near 0 degrees C (rain-snow transition layer) among WPs, which can alter the spatial distribution and frequency of heavy wet snowfall. The findings can help inform structural design requirements to withstand regional climate change.