09:45 〜 10:00
[ACG32-04] Impacts of atmospheric and oceanic changes due to historical climate change on heavy snowfall in Northern Japan
キーワード：降雪、気候変動
Historical climate changes have increased the amount of snowfall induced by the winter monsoon in Japan [1]. In this case, while historical atmospheric warming increased atmospheric stability and suppressed precipitation, oceanic warming increased latent heat flux and low-level atmospheric instability over the Sea of Japan, resulting in increased snowfall. Therefore, to assess the impact of climate change on snowfall, it is necessary to consider both atmospheric and oceanic effects. Moreover, the local impact of climate change varies with the background atmospheric conditions; for example, the impacts of climate change on snowfall are different between days under strong cold outbreaks (winter monsoon) and the passage of extratropical cyclones [2].
Our study investigated the impact of atmospheric and oceanic changes on snowfall events due to historical climate change. We selected events similar to the heavy snowfall in mid-December 2021, characterized by the passage of extratropical cyclones, from a large ensemble experiment database. Composite analyses of the atmospheric conditions of these events, under historical and non-warming climate scenarios, showed that the extratropical cyclones passing near northern Japan were more intense due to historical climate change. Regional climate model experiments revealed that the extratropical cyclone brings northward moisture transport, resulting in heavy snowfall in the eastern sector of the cyclone. The effect of oceanic warming on this snowfall event was relatively weak. This suggests that the impacts of the atmospheric and oceanic changes on snowfall vary with the synoptic-scale atmospheric conditions.
References
[1] Kawase, H., Imada, Y., & Watanabe, S. (2022). Impacts of historical atmospheric and oceanic warming on heavy snowfall in December 2020 in Japan. Journal of Geophysical Research, 127(21). https://doi.org/10.1029/2022jd036996
[2] Tamura, K., & Sato, T. (2023). Localized Strong Warming and Humidification Over Winter Japan Tied to Sea Ice Retreat. Geophysical Research Letters, 50(11), e2023GL103522. https://doi.org/10.1029/2023GL103522
Our study investigated the impact of atmospheric and oceanic changes on snowfall events due to historical climate change. We selected events similar to the heavy snowfall in mid-December 2021, characterized by the passage of extratropical cyclones, from a large ensemble experiment database. Composite analyses of the atmospheric conditions of these events, under historical and non-warming climate scenarios, showed that the extratropical cyclones passing near northern Japan were more intense due to historical climate change. Regional climate model experiments revealed that the extratropical cyclone brings northward moisture transport, resulting in heavy snowfall in the eastern sector of the cyclone. The effect of oceanic warming on this snowfall event was relatively weak. This suggests that the impacts of the atmospheric and oceanic changes on snowfall vary with the synoptic-scale atmospheric conditions.
References
[1] Kawase, H., Imada, Y., & Watanabe, S. (2022). Impacts of historical atmospheric and oceanic warming on heavy snowfall in December 2020 in Japan. Journal of Geophysical Research, 127(21). https://doi.org/10.1029/2022jd036996
[2] Tamura, K., & Sato, T. (2023). Localized Strong Warming and Humidification Over Winter Japan Tied to Sea Ice Retreat. Geophysical Research Letters, 50(11), e2023GL103522. https://doi.org/10.1029/2023GL103522