Collaborative Research: Resolving Spatial and Temporal Variations in Near Shore Wind Stress via Advances in High Frequency Radar

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Wind is a critically important driver of ocean waters, so observations of surface winds as they vary in time and location are important to our understanding of ocean circulation. How water moves in the regions near continents can affect the movement of commercial fish stocks, search and rescue efforts, and many other human endeavors in the nearshore region. Yet available buoy or satellite-based wind observations lack the resolution in time and space needed to fully capture the wind as it drives coastal waters. Today, a distributed network of oceanographic radar systems exists which measure ocean currents remotely from land-based stations. This project will use these radars to also observe winds remotely over the range and resolution needed to capture the wind's full effects on the coastal ocean. It will expand on recent efforts to extract the wind's signal from the observations collected by oceanographic radars in Massachusetts, Rhode Island, and California. The team will also deploy wave buoys and autonomous surface vehicles to ground-truth the data collected and refine the models used to translate radar returns into wind speed and direction. These observations will aid weather forecasts, and improve our understanding of the coastal ocean.Existing observations of the surface winds from buoys or satellites provide either high temporal coverage or high spatial coverage of the nearshore, but never both. Land-based high frequency (HF) radars have the potential to fill this observational gap. This work will couple recent theoretical results, high quality radar observations, and independent wind and wave observations to further develop HF radar-based wind extraction models. Using new and existing datasets from both the New England Shelf and Santa Barbara Channel, this effort seeks to improve our understanding of the complex relationship between surface winds and the signals observed by HF radar systems. Validation studies will be carried out in areas observed by multiple types of radar systems and with significant spatial structure in the surface wind field, using both fixed buoy and mobile, Autonomous Surface Vehicle (ASV)-based wind sensors. These observations will be used to refine our understanding of the relationship between surface wind stress and the signal observed by HF radars, enabling accurate and spatially dense observations of wind forcing throughout the coastal zone. The proposed effort will advance recently developed wind extraction models and strengthen parameterized links between radar backscattered power and wind speed and direction. Applying recent developments in direction finding methods and developing improved calibration techniques, the method will be generalized to arbitrary radar systems.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.