This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).As the interface between the warm ocean (which is the primary energy source driving tropical cyclones) and overlying atmosphere in which these storms develop, the hurricane boundary layer (HBL) represents a pivotal conduit for vertical transfer of energy in the form of heat, moisture and momentum embodied by strong winds and underlying ocean currents. The lead investigator will conduct multi-scale numerical modeling studies [including large-eddy simulations using the Weather Research & Forecasting (WRF) model] and analyze special observations to gain improved understanding of the HBL and optimize its representation in weather forecast models. Particular attention will be directed to methods for improved observation and prediction of damaging wind patterns accompanying storm landfall. Specific objectives of this effort include: (1) advancement of physically-based understanding of HBL processes including their up-scale impact on tropical cyclone energetics and down-scale influences on coastal damage patterns; (2) improved representation of "sub-scale" HBL processes not routinely resolved by numerical simulations through derivation of sophisticated parameterizations uniquely suited to strong hurricane wind conditions; and (3) identification and development of novel approaches to map and predict HBL wind patterns at the time of storm landfall to better support efforts to mitigate coastal hurricane impacts. In conjunction with these simulation-based methodologies, analysis of special observations from CBLAST (the Coupled Boundary Layers Air-Sea Transfer field campaign) and enhanced measurements from two portable coastal wind measurement towers will be conducted. This integrated approach will allow improved understanding and representation of features such as intensely-rotating mesovortices and horizontal "roll" circulation structures embedded within broader cyclonic airflows that influence the strength and duration of damaging surface wind patterns beneath landfalling tropical storms. The intellectual merit of this effort centers upon an improved physical and dynamically-based understanding of atmospheric processes and air-sea interactions influencing hurricane behavior, including mechanisms controlling hurricane formation, intensification and dissipation. Broader impacts will be derived through expansion of both undergraduate and graduate course offerings at Florida International University (a minority-serving institution), outreach to K-12 students through installation of meteorological instrumentation and follow-on interactions at a nearby high school to enhance student awareness and understanding of life-threatening tropical weather events, and ultimately through improved hurricane forecasts and reduced loss of life and property within populous coastal zones.