Recent increase in extreme intensity of tropical cyclones making landfall in South China
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Recent increase in extreme intensity of tropical cyclones making landfall in South China Kin Sik Liu1 · Johnny C. L. Chan1 Received: 1 January 2020 / Accepted: 25 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study examines the interdecadal variations in the frequency and intensity of tropical cyclones (TCs) making landfall in South China (SC) during the period 1975–2018. The annual frequency shows a decrease in 1997 but rises again since 2008 and the annual maximum landfall intensity (MLI) shows an increase since 2012. According to these variations, three subperiods, 1975–1996 (higher frequency but lower MLI), 1997–2011 (lower frequency and MLI) and 2012–2018 (higher frequency and MLI), are defined. The increase in MLI during 2012–2018 is related to the increases in the frequency of (1) TCs undergoing rapid intensification over the South China Sea (SCS) and landfalling in SC, with higher maximum intensity and location of maximum intensity closer to the coast of SC, and (2) intense typhoons (ITYs) over the western North Pacific (WNP), which maintain high intensity before landfall. These changes are closely related to the lower vertical wind shear and higher TC heat potential over the ocean east of the Philippines and the northern part of the SCS. Such an environment is more conducive for TC intensification, leading to the observed increases in the number of rapid-intensifying TCs over the SCS and ITYs over the WNP. Some of these latter TCs move across the SCS and tend to maintain high intensity during landfall in SC. The steering flow also changes, which allows more TCs to enter the SCS, resulting in an increase of ITYs making landfall in SC. Keywords Tropical cyclone landfall · Tropical cyclone intensity · South China · Climate change
1 Introduction With global climate change, interdecadal variability of the tropical cyclone (TC) activity over the western North Pacific (WNP) has become a topic of great interest and research during the last decade (e.g. Chan 2008; He et al. 2015; Choi et al. 2017). Some studies have also examined the interdecadal variations over the South China Sea (SCS), a semi-enclosed marginal sea in the WNP (Fig. 1). TCs occurring in the SCS include those that form within the SCS or enter the SCS from the WNP. Some studies investigated the interdecadal variations of TC genesis in the SCS and found two decadal shifts in 1993/1994 and 2002/2003, which are related to the warming of the northern Indian Ocean and the western Pacific Ocean (Ha and Zhong 2015), the zonal * Kin Sik Liu [email protected] 1
Guy Carpenter Asia‑Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong, Tat Chee Ave., Kowloon, Hong Kong, China
sea-surface temperature (SST) gradient between the northern Indian Ocean and the WNP (Li and Zhou 2014), the localized atmospheric intraseasonal variability (Ha et al. 2014; Li et al. 2019) and the east-westward movement of the subtropical high over the SCS (Li et al. 2019). However, very few studies
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