The Impact of Storm-Induced SST Cooling on Storm Size and Destructiveness: Results from Atmosphere-Ocean Coupled Simulat
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Volume 34
OCTOBER 2020
The Impact of Storm-Induced SST Cooling on Storm Size and Destructiveness: Results from Atmosphere–Ocean Coupled Simulations Tao GUO, Yuan SUN*, Lei LIU, and Zhong ZHONG College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101 (Received January 4, 2020; in final form May 20, 2020)
ABSTRACT In this study, both an atmospheric model [Weather Research and Forecasting (WRF) model] and an atmosphere (WRF)–ocean (Princeton Ocean Model; POM) coupled model are used to simulate the tropical cyclone (TC) Kaemi (2006). By comparing the simulation results of the models, effects of oceanic elements, especially the TC-induced sea surface temperature (SST) cooling, on the simulated TC size and destructiveness are identified and analyzed. The results show that there are no notable differences in the simulated TC track and its intensity between the uncoupled and coupled experiments; however, there are large differences in the TC size (i.e., the radius of gale-force wind) between the two experiments, and it is the TC-induced SST cooling that decreases the TC size. The SST cooling contributes to the decrease of air–sea moisture difference (ASMD) outside the TC eyewall, which subsequently leads to the decreases in surface enthalpy flux (SEF), radial sea-level pressure gradient, absolute vorticity advection, and wind speed outside the TC eyewall. As a result, the TC size and size-dependent TC destructive potential all decrease remarkably. Key words: tropical cyclone (TC) size, destructiveness, sea surface temperature (SST) cooling Citation: Guo, T., Y. Sun, L. Liu, et al., 2020: The impact of storm-induced SST cooling on storm size and destructiveness: Results from atmosphere–ocean coupled simulations. J. Meteor. Res., 34(5), 1068–1081, doi: 10.1007/s13351-020-0001-2.
1.
Introduction
Tropical cyclone (TC) is one of the most severe weather systems on the earth, which brings about incalculable consequences to human life (Easterling et al., 2000; Peduzzi et al., 2012). Currently, TC forecasts generally focus on the TC track and intensity. Meanwhile, the potential wind damage near the TC center is also estimated. The TC intensity is expressed by either the minimum sea-level pressure or the maximum sustained wind speed (MWS) near the surface TC center. Because track and intensity are two important TC properties, many studies have been conducted to investigate the physical processes responsible for the TC intensity and track changes (Elsner et al., 2008; Kossin et al., 2014, 2016). Nonetheless, a broader understanding of TC properties should not be limited to only these two variables. The TC
size is also an important metric, and it is actually associated with the changes of TC intensity and track (Chavas et al., 2016; Sun et al., 2017), and with the structure of TC wind field (Chan and Chan, 2013, 2014, 2015; Chavas et al., 2015; Wang et al., 2015; Chavas and Lin, 2016). The definition of TC size is different in many previous studies. For example, some used the azimuthall
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