A case application of WRF-UCM models to the simulation of urban wind speed profiles in a typhoon. Issue 220 (January 2022) - Zhang, Yuxin
Abstract: In order to work out a reliable way to predict urban wind speed profiles during typhoon process, in this study, WRF-UCM coupled models are adopted to simulate an urban wind field during the landfall of a strong typhoon. Sensitivity analysis is first carried out to obtain the best typhoon track simulation, based on which the PBL scheme of Mellor-Yamada-Janjic (MYJ) and the Microphysics model of Purdue Lin (LIN) are chosen for successive simulations. A WUDAPT based Local Climate Zone (LCZ) map is drawn to replace and supplement the default underlying surface data to execute WRF-UCM coupled simulations. After examining the accuracy of the WRF-UCM simulation, the mean wind speed profiles, turbulence intensity profiles and power spectra of simulated wind fields are studied to evaluate the applicability of different UCMs to the urban typhoon simulation. Utilizing multi-layer UCM (ML-UCM) leads to a notable weakening of mean wind speed and a slight increase of turbulence intensity within lower altitudes while slab UCM (SB-UCM) or single-layer UCM (SL-UCM) shows little effect. In general, coupling suitable UCM into the WRF model can improve urban typhoon wind profiles simulation. Nevertheless, it is still hard to perfectly reproduce real typhoon wind profiles via WRF-UCM coupling models. Highlights: Applicability of WRF-UCM models to the simulation of urban wind speed profiles in a typhoon is investigated. Combination of MYJ-PBL scheme and the LIN Microphysics model leads best typhoon simulation results for WRF-UCM. The ML-UCM leads the most improved simulation results of urban typhoon wind profiles. It is hard to perfectly reproduce real typhoon wind profiles via WRF-UCM models.