sUAS Observations of Turbulent fluxes in the Hurricane Boundary Layer

Theoretical and numerical studies have shown that turbulent processes in the boundary layer are important for hurricane intensity change. However, it is extremely difficult to collect in-situ turbulence data in this region due to instrument limitations and safety concerns. This study reports direct turbulence observations using small uncrewed aircraft systems (sUAS) in the 2024 hurricane season. Turbulence structure in both eyewall and outer-core regions is examined in terms of spectral and cospectral characteristics. Universal spectra and cospectra of wind velocities are derived following the similarity theory scaling. The horizontal scales of turbulent eddies that dominate momentum transfer and their variations with height and radial locations are quantified. Coherent structures are identified, and their impacts on turbulent parameters are estimated. Experimental design and observational strategy optimization are discussed.