[A-CG36] Extratropical oceans and atmosphere

[ACG36-P10] Impact of a wintertime marine heatwave on a heavy rainfall event in northern Japan in January 2024

*Shito Fukuda¹, Kazuaki Nishii¹, Shusaku Sugimoto² (1.Graduate School of Bioresources, Mie University, 2.Graduate School of Science, Tohoku University)

Keywords:marine heatwave, SST

Since the spring of 2023, the Kuroshio Extension has shifted northward just east of the Tohoku district in northern Japan, leading to a marine heatwave (MHW) off the coast of Tohoku. Although impact of the MHW on summertime climate in Japan has been pointed out, that on wintertime Japan has not yet been clarified. This study focuses on a heavy rainfall event along the eastern coast of Tohoku on 21 January 2024. During this event, daily precipitation was the largest in January in recorded history at several observation points. This heavy rainfall might have been influenced by the MHW because a low-pressure system, whose southeasterly wind brought the heavy rainfall, passed over the MHW. By conducting regional atmospheric model experiments, it is found that the MHW off the coast of Tohoku increased rainfall along the Tohoku coast in association with warming there. While it tends to snow in Tohoku in winter, this case saw an increase in rainfall rather than snowfall, potentially impacting agriculture and social activities. The findings of this study are expected to contribute to improving the accuracy of weather forecasts in this region.