Veer and shear in the tropical cyclone lower boundary-layer

Tropical cyclones are associated with extreme wind speeds, enhanced turbulence, vertical wind shear, and veer. All these elements increase loads acting on structures such as wind turbines, bridges, and high-rise buildings. While most studies focus on maximal wind speeds in tropical cyclones, we analyze wind shear and veer in the lowest 300 m of the atmosphere, which is relevant for wind energy applications. We use the Weather Research and Forecasting model to model and analyze the distribution and spatial structure of wind shear and veer in Typhoon Megi (2016) at different radii. We found maximal mean shear and veer in the eyewall region. Shear and veer are on average smaller in the rainbands, but their respective distribution is positively skewed due to spatially organized outliers. These outliers are associated with convective cells and downdrafts, that propagate over structures with speeds of around 30 ms⁻¹. Consequently, structures experience rapid changes in shear and veer. We further analyze vertical cross-sections through convective cells and their propagation velocity. The study highlights differences in characteristics of the low-level wind field between the eyewall region and rainbands, which suggest distinct forces acting on structures.