PhD Proposal Defense: Shuo Li

The PhD Proposal Defense of Shuo Li is presented by the University of North Carolina at Chapel Hill’s Earth, Marine, and Environmental Sciences Department. This event will be held on the Friday, February 4th at 3:00 pm. This event will be  streamed online. To watch online join via Zoom Meeting ID 980 2113 4576.

Title: The control of tropical sea surface temperatures on tropical cyclones in the Northern Hemisphere

Abstract: Tropical cyclones (TCs) are one of the most common severe weather systems and impose great impacts on coastal communities and economy. The genesis of TCs is substantially subject to the underlying sea surface temperatures (SSTs) conditions. Several SST factors [e.g. ENSO, SST anomalies over the tropical North Atlantic (NA) and North Indian Ocean (NIO)] have been identified to modulate TC genesis in the Northern Hemisphere ocean basins [including the NA, Northeast Pacific (NEP), Northwest Pacific (NWP) and NIO]. However, it is still unclear whether these SST factors are independent, and their relative contributions to TC genesis remain to be quantified. To fully understand the variability of tropical SSTs and its impacts on TC genesis, (1) The leading modes of tropical SST variability during the TC peak season (June–November) will be extracted via an empirical orthogonal function (EOF) analysis. Then the individual and combined effects of these SST modes on TC genesis in each Northern Hemisphere ocean basin will be quantified. Further, the SST effects are interpreted by analyzing the response of a genesis potential index (GPI) and its components to the identified SST modes. (2) To examine the variations in the associations between ENSO and TC genesis, sliding-window correlations are used to analyze the unstable linkage between ENSO and TC genesis in the tropical NA, NEP, and NWP, respectively. Then the entire time period will be divided into two sub-periods, and the impacts of ENSO on large-scale atmospheric circulations during each sub-period will be analyzed to reveal the underlying physical mechanisms. (3) The variability of TC genesis density in the NWP will be studied using TCs from the simulations by a 60-km-resolution atmospheric general circulation model (AGCM) that is forced by observed SSTs. The dominant modes on interannual and decadal time scales will be determined. The seasonal evolution of the ENSO effect on TC genesis will be further explored using TC genesis density of consecutive seasons. The proposed research will systematically explore the effects of tropical SSTs on TCs and be of great importance for better prediction of TC genesis in the Northern Hemisphere.