11:00 〜 11:15
[ACG36-02] Role of Kuroshio Warming in Intensifying the Mei-yu-baiu Rainband: A Quantitative Study
キーワード：Mei-yu-baiu, Kuroshio , SST increase, climate model
With the increasing sea surface temperature (SST) over the Kuroshio in the East China Sea (ECS), precipitation has significantly intensified during the mei-yu-baiu season over the last four decades. However, the extent to which changes in SST contributed to the intensified mei-yu-baiu precipitation remains unknown. Therefore, in this study, we aimed to quantify the contribution of Kuroshio warming to increased precipitation. We first simulated recent (2018–2022; RtRa) and past (1979–1983; HtHa) East Asian atmospheres for each June. Next, we conducted a set of sensitivity experiments (HtRa and RtHa) in which the SSTs used in the RtRa and HtHa were exchanged sequentially. The simulated precipitation averaged within the ECS–Kuroshio region increased by approximately 5.57 mm/day during the last four decades. Meanwhile, 37% of that was mainly contributed by the SST increase over the ECS–Kuroshio.
We revealed that the precipitation responded to ECS–Kuroshio warming through a combination of the following two mechanisms: 1. Intensified evaporation increased the equivalent potential temperature in the marine atmospheric boundary layer, which effectively destabilized the mid-to-upper troposphere and favored the development of local convection through the convective instability. 2. Increased SST and enhanced SST fronts over the ECS–Kuroshio intensified the near-surface wind convergence and upward movement by strengthening the near-surface low pressure that was anchored along the ECS–Kuroshio, which can amplify the convective activities.
We revealed that the precipitation responded to ECS–Kuroshio warming through a combination of the following two mechanisms: 1. Intensified evaporation increased the equivalent potential temperature in the marine atmospheric boundary layer, which effectively destabilized the mid-to-upper troposphere and favored the development of local convection through the convective instability. 2. Increased SST and enhanced SST fronts over the ECS–Kuroshio intensified the near-surface wind convergence and upward movement by strengthening the near-surface low pressure that was anchored along the ECS–Kuroshio, which can amplify the convective activities.