[A-CG42] Science in the Arctic Region

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

*Kazuyoshi Suzuki¹, Milija Zupanski², Takashi Dan^1,3, Akira Yamazaki¹, Hotaek Park¹, Tetsuya Hiyama⁴, Go Iwahana⁵, Hideki Kobayashi¹ (1.Japan Agency for Marine-Earth Science and Technology, 2.Colorado State University, 3.Yokohama National University, 4.ISEE, Nagoya University, 5.IARC, University of Alaska at Fairbanks)

Keywords:extreme weather, winter, precipitation, blocking high pressure

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.