Changes in tropical cyclone response to the Boreal Summer Intraseasonal Oscillation in the western North Pacific under global warming in EC-Earth3P-HR

EC-Earth3P-HR reproduces well the observed Boreal Summer Intraseasonal Oscillation (BSISO) and its impacts on tropical cyclone genesis (TCG) in the western North Pacific (WNP). Hence, the historical simulation (1950- 1979) and future projection under the SSP5-8.5 scenario (2020-2049) in EC-Earth3P-HR are adopted to explore possible changes in the BSISO's modification of WNP TCG under global warming to enhance the understanding of TC activities in the WNP. Results show that the BSISO circulation in the WNP shifts northeastward under global warming. This leads to enhanced convection in a northwest-southeast-oriented band crossing the WNP. Along the band, the BSISO-related TCG anomalies are enhanced. Analyses of genesis potential index show that changes in the BSISO-related mid-tropospheric relative humidity play the dominant role in modifying the BSISO's impacts on WNP TCG under global warming. The enhanced BSISO convection in the band moistens the middle troposphere, which helps reduce the entrainment of generally dry mid-tropospheric air in the updrafts and the modification of the boundary layer by the downdraft of generally dry mid-tropospheric air, leading to enhanced TCG.