Relating Wind and Wave Patterns to Momentum Flux and Surface Drag Variability in Tropical Cyclones

Many observational and modeling studies have highlighted that air-sea interaction plays a crucial role in tropical cyclone (TC) intensity change. One of the many ways the ocean and atmosphere interact is the transfer of momentum between the boundary layers. Numerical TC forecast models replicate this process through a surface drag coefficient that regulates the amount of momentum exchanged between the ocean and atmosphere. However, the few direct measurements and several indirect methodologies of estimating momentum flux and surface drag coefficient vary greatly amongst each other and have high estimation uncertainty. While there have been several prior observational studies in TC wind regimes to reduce this variability and uncertainty, resultant studies have been siloed to a particular boundary layer (air, ocean, or wave). Hence, there is a need to concurrently observe, examine, and quantify the relative contribution of processes that govern the exchange of momentum between the atmosphere, ocean, and wave boundary layers in a TC to discern if an accurate physical understanding of their interaction is being considered in modeled parameterizations. We attempt this here through estimating momentum flux through wave spectra and characterizing observations by various TC parameters to identify how the TC wave field influences momentum transfer. Then, these findings are compared to momentum flux estimates from atmospheric dropsonde observations manipulated in similar fashion with respect to TC parameters to discern if wave characteristics are imprinted on momentum flux estimates in the atmosphere.