Influence of Future Tropical Cyclone Track Changes on Their Basin-Wide Intensity over the Western North Pacific: Downscaled CMIP5 Projections

The possible changes of tropical cyclone (TC) tracks and their influence on the future basin-wide intensity of TCs over the western North Pacific (WNP) are examined based on the projected large-scale environments derived from a selection of CMIP5 (Coupled Model Intercomparison Project Phase 5) models. Specific attention is paid to the performance of the CMIP5 climate models in simulating the large-scale environment for TC development over the WNP. A downscaling system including individual models for simulating the TC track and intensity is used to select the CMIP5 models and to simulate the TC activity in the future. The assessment of the future track and intensity changes of TCs is based on the projected large-scale environment in the 21st century from a selection of nine CMIP5 climate models under the Representative Concentration Pathway 4.5 (RCP4.5) scenario. Due to changes in mean steering flows, the influence of TCs over the South China Sea area is projected to decrease, with an increasing number of TCs taking a northwestward track. Changes in prevailing tracks and their contribution to basin-wide intensity change show considerable inter-model variability. The influences of changes in prevailing track make a marked contribution to TC intensity change in some models, tending to counteract the effect of SST warming. This study suggests that attention should be paid to the simulated large-scale environment when assessing the future changes in regional TC activity based on climate models. In addition, the change in prevailing tracks should be considered when assessing future TC intensity change.