Sub-Seasonal Forecast of Global Marine Heatwaves Based on NUIST CFS1.1

Marine heatwaves (MHWs), which can exert devastating socioeconomic and ecological impacts, have attracted much public interest in recent years. In this study, we evaluate the sub-seasonal forecast skill of MHWs based on the Nanjing University of Information Science & Technology Climate Forecast System version 1.1 (NUIST CFS1.1) and analyze the related physical processes. Our results show that the model can accurately forecast the occurrence of MHWs on a global scale out to a lead time of 25 days. Notably, even at lead times of 51–55 days, the forecast skill in most tropical regions, as well as in the northeastern and southeastern Pacific, is superior to both random forecasts and persistence forecasts. Accurate predictions of sea level pressure, zonal currents, and mixed-layer depth are important for MHW forecasting. Furthermore, we also conduct forecast skill assessments for two well-documented MHW events. Due to its ability to correctly forecast the changes in heat flux anomalies at a lead time of 25 days, the model can accurately forecast the strong MHW event that occurred in the South China Sea in May–October 2020. However, the forecasting results were less than optimal for the strong MHW event that occurred along the Australian west coast in January–April 2011. Although the model accurately forecasts its occurrence, the forecast of its intensity is poor. Additionally, when the lead time exceeds 10 days, forecasts of the relevant physical processes of this MHW event are also inaccurate.