[A-CG46] 北極域の科学

[ACG46-P09] Winter heavy precipitation event in interior Alaska in December 2021

*鈴木 和良¹、平島 寛行²、岩花 剛³、朴 昊澤¹、小林 秀樹¹ (1.国立研究開発法人海洋研究開発機構、2.国立研究開発法人防災科学技術研究所、3.アラスカ大学フェアバンクス校　国際北極圏研究センター)

キーワード：極端気象、積雪上降雨、永久凍土

A record-breaking precipitation event was observed in interior Alaska in December 2021, with daily maximum precipitation of nearly 100 mm in both Fairbanks and Poker Flat, located farther north in the near Arctic Circle, on December 26. Monthly precipitation in December exceeded 200 mm at both locations, with Poker Flat recording the higher precipitation. The Japan Agency for Marine-Earth Science and Technology (JAMSTEC), in collaboration with the University of Alaska, has set up a tower at the Poker Flat supersite to intensively observe the water and carbon cycles of the boreal forest, and is simultaneously conducting meteorological and subsurface observations. In this study, we will clarify the contribution of rainfall and snowfall to precipitation events exceeding summer precipitation in the Arctic in late December using a snow model, in-situ observation and reanalysis dataset. In addition, the effects of record-breaking precipitation events on the snowpack layer and the water and energy balance were analyzed from the snowpack model. Snowpack model simulations and data analysis revealed that the December precipitation event included significant amounts of rainfall. And the rainfall affected not only the snowpack but also the underlying soil freezing. In the end, we will also discuss how record-breaking precipitation events are related to long-term climate change such as global warming.