On the Influence of Oceanic Variability on Air-Sea Heat Fluxes and Boundary Layer Recovery in Hurricanes

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The controlling factors that impact the rapid intensification of hurricanes remain a scientific and forecasting uncertainty. In this award, the research team will use observational data to test a new theory about the interaction between the air and sea during the key periods in the hurricane life-cycle that lead to rapid strengthening of these storms. The project has direct societal relevance due to the importance of accurate forecasts of hurricane intensity changes. The project will also provide graduate students with the opportunity to plan, organize, and execute a field experiment. This award is for the investigation of key thermodynamics processes of coupled air-sea interaction in tropical cyclones (TCs) relative to vertical shear and oceanic features. The main conceptual theory is that areas with high oceanic heat content and minimal sea surface cooling exert localized buoyancy forcing on TCs during rapid intensification due to enhanced moisture disequilibrium and intense surface heat fluxes. This process leads to a rapid and sustained recovery of the atmospheric boundary layer equivalent potential temperature. To test this hypothesis, the PI team will use data collected during prior TCs and participate in new data collection in collaboration with NOAA during the period of the project. The specific research objectives are to: 1) Synthesize in-situ atmospheric and oceanographic data and satellite SST data, and compute air-sea temperature and moisture disequilibrium, bulk air-sea heat fluxes, and recovery of atmospheric boundary layer equivalent potential temperature during selected Atlantic-basin hurricanes, focusing on previous data acquired over various levels of OHC and upper-ocean stratification; 2) Observe and understand the air-sea interaction during TC intensity change over warm oceanic eddy regimes by simultaneously deploying oceanic and atmospheric profilers during storm passage; and 3) Develop a framework for characterizing the temporal and spatial scales of variability of the air-sea interaction and storm intensity for the selected TCs in terms of oceanic and atmospheric parameters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.