Boundary Layer Wind Structure and Ocean Waves in Tropical Cyclones from SAR Imagery

This dissertation examines boundary layer winds and ocean surface waves within tropical cyclones using Synthetic Aperture Radar (SAR) from satellites. The study focuses on the atmospheric boundary layer's bottom two kilometers, crucial for energy exchange between storms and the ocean surface, influencing tropical cyclone intensity and trajectory. SAR's capability to penetrate clouds and provide high-resolution, sunlight-independent sea surface measurements enables the retrieval of detailed wind and wave data at 1 km spatial resolution. Utilizing in-situ and model data from the 2010 Impact of Typhoons on the Ocean in the Pacific experiment, this research validates SAR-derived wind and wave products. It compares two SAR images of Typhoon Megi, taken 12 minutes apart with different wavelengths, to assess wind retrieval algorithms. Findings indicate that SAR winds align with in-situ data, though X-Band signals saturate at winds over 30 m/s, suggesting limitations in high-frequency microwave use for extreme wind conditions. The study also inputs SAR winds into a boundary layer model to simulate and validate 3D wind patterns against dropsonde data, investigating roll vortices and supergradient winds. Additionally, it applies an empirical model to SAR winds to estimate significant wave heights under cyclone conditions, identifying the need for model reparameterization to correct wave height estimations. Analysis of 23 days of buoy data on wave height and inertial currents post-tropical cyclone shows significant modulation, highlighting inertial currents' impact. This work underscores SAR's value in marine and atmospheric research, offering insights into tropical cyclones' complex dynamics and their effects on wind and wave patterns.