[A-CG42] 北極域の科学

[ACG42-P08] Understanding the December 2021 Extreme Precipitation Event in Interior Alaska Using the Arctic Regional Reanalysis (ARR) and ERA5

*鈴木 和良¹、Zupanski Milija²、段 卓志^1,3、山崎 哲¹、朴 昊澤¹、檜山 哲哉⁴、岩花 剛⁵、小林 秀樹¹ (1.国立研究開発法人海洋研究開発機構、2.コロラド州立大学、3.横浜国立大学、4.名古屋大学宇宙地球環境研究所、5.アラスカ大学北極圏研究センター)

キーワード：極端気象、冬季、降水、ブロッキング高気圧

A record-breaking precipitation event was observed in interior Alaska on 26 December 2021, with daily maximum precipitation of nearly 100 mm in both Fairbanks and Poker Flat, located farther north in the near Arctic Circle. Monthly precipitation in December exceeded 200 mm at both locations, with Poker Flat recording the higher precipitation. In this study, we will clarify the contribution of rainfall and snowfall to the precipitation events exceeding summer precipitation in the Arctic using in-situ observation and reanalysis dataset. In addition, the effects of record-breaking precipitation events on the snowpack and soil layer and the water and energy balance were analyzed. At the same time, we are developing an Arctic region system reanalysis (ARR) using Polar WRF-MLEF. We attempted to reproduce anomalous precipitation from the reanalysis values by using our reanalysis system. Also, we assessed the impact of AMSR2's Sea surface wind retrieval.
Analysis using ERA5 and ARR suggested the influence of a low-pressure system developed on the Kamchatka Peninsula and a blocking high-pressure system over the Northeast Pacific Ocean in the south of Alaska as a cause of the extreme precipitation. In addition, high sea surface temperature anomaly in the Kuroshio extension enhanced water vapor supply to the atmosphere.