A Multiscale Diagnostic and Prognostic Investigation of Environmental Influences on Tropical Cyclone Life Cycles

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The purpose of this research is to conduct detailed diagnostic and prognostic analyses of tropical cyclones from genesis to extratropical transition (ET). The research will be conducted in two stages. In stage one, a detailed diagnostic analysis will be conducted for historical storms as well as all Atlantic tropical cyclones over the course of one or two complete storm seasons. The life history of each storm will be tracked and documented beginning several days before tropical depression definition and ending when the storm has dissipated or undergone extratropical transition. The goal of stage one is to identify the variety of tropical and midlatitude disturbances responsible for the development of tropical cyclones in the Atlantic basin. Further, the upscale impact of significant cyclogenesis/transition events on the large-scale flow will also be examined. In stage two, numerical simulations of representative storms will be conducted to test physical hypotheses formulated from the diagnostic analyses completed in stage one. Tropical cyclogenesis, intensity changes, recurvature, and tropical transition occur across a variety of large-scale tropical and subtropical environments. Each event may result from the presence of a single feature in the large-scale flow (e.g., easterly wave; midlatitude upper-level trough or potential vorticity [PV] anomaly) or may involve the interaction of multiple features in the flow. The contribution of single-feature and multiple-feature environmental forcings in tropical cyclogenesis and extratropical transition remains unclear and needs to be quantified. Diagnosing all storms within a storm season will address the relative importance of one-time forcing and multiple forcings events.The primary datasets used in this study will be operational gridded analyses fields. Advantage will be taken of the abundant satellite-derived upper-tropospheric water winds. The available datasets will allow for the detailed analysis of tropical cyclogenesis and extratropical transition over the oceans.The broader impacts of this proposal follow from the fact that tropical cyclones at any stage of their life cycle can pose a serious threat to life and property to mariners at sea, to coastal residents and to inland inhabitants. By examining a spectrum of tropical cyclone life cycles in detail it is hoped that the basic knowledge gained may have operational application in the area of tropical cyclone track/intensity forecasting and quantitative precipitation estimation. This project also presents the opportunity to work with various government and civilian agencies and other educational institutions to help facilitate the transfer of knowledge to operations and to students.