Can the Mann model describe the typhoon turbulence?

Abstract. More and more wind farms are planned and built in regions prone to tropical cyclones. However, the current International Electrotechnical Commission (IEC) standard provides no clear guidelines on how to account for turbulence occurring during tropical cyclones. This study investigates how well the Mann turbulence model, a model referenced by the IEC, can model turbulence during tropical cyclone conditions. We analyzed sonic anemometer measurements at 60 m from four typhoon cases in the South China Sea. The Mann model was fit to the one-point spectra in different locations in the typhoon structure. We found that the Mann model can fit the observed spectra reasonably outside the typhoon eye and the rainbands. However, deficiencies are found regarding the following aspects: 1.) In the outer cyclone region, excessive energy is found at low wavenumbers smaller than 10^−2.5 m⁻¹ associated with quasi-two-dimensional turbulence, 2.) In the inner cyclone and eyewall regions of one of the typhoons, we observe excessive energy at wavenumbers larger than 10⁻¹m⁻¹, 3.) Enhanced 10 energy is found in the energy-containing subrange of the crosswind component in the inner cyclone region, and 4.) The energy level of the uw-cospectra is overestimated in the fitted Mann model. This study can serve as a baseline for further research addressing turbulence in tropical cyclones in the context of structural engineering.