[A-CG31] Climate Variability and Predictability on Subseasonal to Centennial Timescales

[ACG31-P08] Future marine heatwaves around Japan based on high-resolution ensemble simulations

*Yuma Kawakami¹, Hideyuki Nakano¹, Shogo Urakawa¹, Takahiro Toyoda¹, Kei Sakamoto², Shiro Nisikawa³, Toru Sugiyama³, Masao Kurogi³, Yoichi Ishikawa³, Katsunari Sato², Goro Yamanaka¹ (1.Meteorological Research Institute, 2.Japan Meteorological Agency, 3.Japan Agency for Marine-Earth Science and Technology)

Keywords:Marine Heatwaves, Northwestern Pacific Ocean, Future projections

Marine heatwaves (MHWs) are oceanic conditions with extremely high sea surface temperature (SST) anomalies that last for several days to years. Since MHWs have devastating effects on marine ecosystems and significant impacts on fisheries, insights into future MHWs are important for adapting to upcoming climate changes. In this study, we examined future changes in MHWs around Japan under two CO2 emission scenarios using a high-resolution ensemble (four members for each scenario) simulation product using a high-resolution ocean model that satisfactorily resolves the Kuroshio, Kuroshio Extension, and SST fronts. High-resolution multi-scenario ensemble future projections of MHWs are advanced efforts in MHW researches.
Following global warming, MHWs will increase and intensify (i.e., occur with higher SST anomalies than before). In the historical period (1981–2005), the annual MHW days is 20–34 days. Annual MHW days increase to 63–313 days (188 days–all year round) depending on the region under the high CO2 mitigation (emission) scenario at the end of the 21st century of 2076–2100. We further investigated the spatial details of future MHWs. Future MHWs reflect the magnitude of SST variability in addition to that of sea surface warming in the 21st century; future MHWs are less frequent and more intense in the subtropical–subarctic frontal zone with large SST variability than in other regions.