Impact of ocean warming on tropical cyclone track over the western north pacific: A numerical investigation based on two case studies

The impact of ocean warming on tropical cyclone (TC) track over the western North Pacific is an open issue. Relatively little is known about possible changes in TC tracks under ocean warming conditions due to both inhomogeneous observation networks and large natural variability over a relatively short observational period. A suite of semiidealized numerical experiments on two TC cases is conducted to investigate the response of TC tracks to increases in sea surface temperature (SST). It is found that the simulated TC track is highly sensitive to underlying SST. Specifically, through its influence on the radial distribution of sea surface enthalpy, ocean warming can lead to changes in the tangential wind profile and thus increase the TC size in terms of the radius of gale force wind, which is attributed to the increase in maximum wind speed, the expansion of the radius of maximum wind, and the additional increase in outer winds. The increased TC size, as suggested by previous studies, further leads to the eastward withdrawal of the western Pacific subtropical high (WPSH) and thus a northward turning of the TC. Results of climate simulations in the present study provide further evidence for the aforementioned impact of ocean warming on TC size and thus the WPSH and TC track. Results of the present study also imply that the threat of storms to countries in East Asia may be reduced due to possible changes in TC tracks if ocean warming continues in the future. Plain Language Summary In this paper we investigate the impact of ocean warming on tropical cyclone (TC) track over the western North Pacific (WNP). Our model results show that as the sea surface temperature (SST) increases, the TC expands significantly amplifying the influence of TC on the surrounding environmental flow associated with the western Pacific subtropical high and eventually leading to the northward turning of TC over the WNP. Our results also implies that the threat of storm to the countries in the East Asian may reduce due to the change of TC track if ocean warming happens in future.