Tropical Cyclone Frequency Under Varying SSTs in Aquaplanet Simulations

Abstract

Global tropical cyclone (TC) frequency is investigated in a 50‐km‐resolution aquaplanet model forced by zonally symmetric sea surface temperature (SST). TC frequency per unit area is found to be proportional to the Coriolis parameter at the intertropical convergence zone (ITCZ), as defined by the latitude of maximum precipitation. As the latitude of maximum SST is shifted northward from the equator, the precipitation maximum moves northward and TC frequency increases. When the SST maximum is shifted northward past 25°N, the precipitation maximum remains between 15°N and 20°N, and TC frequency per unit area is approximately constant. When applied to observed precipitation and SST data, the same scaling captures a substantial fraction of observed TCs. Results suggest that future changes in TC activity will be modulated by changes in the large‐scale circulation, and in particular that the ITCZ location is an important determinant of the number of TCs.

Evolving Tropical Cyclone Tracks in the North Atlantic in a Warming Climate

“…It is reasonable to anticipate that this region could see increased TC activity in the future with another migration of the ITCZ (Burnett et al, 2021;Van Hengstum et al, 2016). Given that variation in the ITCZ position is driven partially by differential heating and cooling of the hemispheres (Broccoli et al, 2006), and given the amplified warming of the northern hemisphere relative to the southern hemisphere in a warming climate (Stocker et al, 2013), it is plausible that a northward shift in the ITCZ could help drive increased density of TC genesis along the U.S. southeast coast in the future.…”

Tropical Cyclone Frequency

“…Over the full range of idealized simulations, the response of TC frequency to climate warming appears to result from changes in circulation associated with the pattern of warming, with the ITCZ latitude of fundamental importance (Ballinger et al, 2015;Burnett et al, 2021;Merlis et al, 2013;Viale & Merlis, 2017; G. (Khairoutdinov & Randall, 2003) with 5 km horizontal grid spacing, and other parameters following Wing et al (2018). It is zonally periodic with rigid walls at the north and south boundaries.…”

“…The essential components of a theory predicting the ITCZ-related control of TC frequency are thus, perhaps, beginning to emerge. They include a theory to predict the latitude of the ITCZ (e.g., Biasutti et al, 2018;Byrne et al, 2018;Schneider et al, 2014), as well as the rate at which TC genesis increases with that latitude (e.g., Burnett et al, 2021;Merlis & Held, 2019), which we might expect to be related to the rate of increase with Coriolis parameter in rotating RCE (e.g., Chavas & Reed, 2019, though we note that the genesis rate increases with ITCZ latitude in Burnett et al, 2021's results much more rapidly than implied by Chavas & Reed, 2019). Additional complexities to be reckoned with would then be how ITCZ strength or structure, vertical shear (e.g., Fedorov et al, 2019;Walsh et al, 2020), zonal variations (e.g., G. Zhang, Silvers, et al, 2021), or other mitigating factors change TC frequency compared to what a relationship with ITCZ latitude alone would predict.…”

The impact of seasonal and event‐based infiltration on transition metals (Cu, Ni, Co) in tropical cave drip water

“…How climate influences tropical cyclone (TC) variability is still debated. [1][2][3][4] In the western tropical Atlantic, that is, Central America and the Caribbean, TC reconstructions rely mainly on coastal archives, such as sedimentary records (e.g., lagoons, marshes), which provide information for the last two millennia. [5][6][7][8] However, records from earlier times are lacking, preventing the study of TC precipitation and infiltration variability on millennial to orbital timescales.…”

“…How climate influences tropical cyclone (TC) variability is still debated 1–4 . In the western tropical Atlantic, that is, Central America and the Caribbean, TC reconstructions rely mainly on coastal archives, such as sedimentary records (e.g., lagoons, marshes), which provide information for the last two millennia 5–8 .…”