Search

This study presents the results of a comparative study of the wind characteristics of three typhoons presenting similar characteristics, based on stationary and nonstationary models. The original data were collected at four different heights along the seaside of the Fujian Province (China), where the typhoons passed through. First, the run-test method and discrete wavelet transform were employed to evaluate the stationarity and extract the time-varying mean wind speed after data filtering. Then, the gust factor, turbulence intensity and turbulence integral scale were compared. The results demonstrated that the wind characteristics described by the nonstationary model were more centralized and stable than those obtained by the stationary model. Lastly, the power spectral density and evolutionary power spectral density (EPSD) were compared, revealing that the von Karman spectra fitted well the measured spectra. In addition, two methods for the analysis of nonstationary wind spectra were compared. The direct extension from stationary model to nonstationary model was found not to be reasonable from the results of this comparison. Considering the instantaneous energy concentration shown in the EPSD, a nonstationary approach is recommended when analyzing near surface typhoon wind data. [ABSTRACT FROM AUTHOR]

A Weather Research and Forecasting (WRF) model simulation with 3-km horizontal grid spacing was coupled with five California Meteorological Model (CALMET) simulations with horizontal grid spacing ranging from 100 m to 3 km to investigate the impact of horizontal resolution on the simulated near-surface wind fields of Super Typhoon Meranti (2016). Assessment of the model output was conducted in two specified regions named Shisun Mountain and Shishe Mountain in Fujian Province, China. The WRF/CALMET coupled system exhibited satisfactory performance, as indicated by the reasonably large correlation coefficient (>0.4) between the simulated and observed winds. The best and second-best outcomes for 10-m wind speed were found in the simulations with horizontal grid spacing of 500 and 250 m, respectively. Specifically, the 10-m wind speed appeared sensitive to model resolution after being affected by the gale-force winds of Typhoon Meranti. For the 10-m wind direction, the best outcome at Shisun Mountain was found with 500-m horizontal grid spacing, whereas it improved continuously with higher horizontal resolution at Shishe Mountain. The wind-followed slope angle was proposed to provide new perspective for quantitative evaluation of the impact of complex terrain with different horizontal resolutions on the near-surface wind field. It is found that, irrespective of the location and model resolution, the 10-m downhill winds were generally larger than the uphill winds before and after being affected by the gale-force winds, while the winds decreased with slope angle in both uphill and downhill situation when affected by the gale-force winds of Typhoon Meranti. • The performance of the WRF/CALMET coupled system was generally satisfactory. • The best and second-best results were found with grid spacing of 500 and 250 m. • A resolution of 100 m results in an overestimation of the measurements. • 10-m winds appeared sensitive to model resolution after being affected by typhoons. • The wind-followed "slope angle" is proposed for quantitative evaluation. [ABSTRACT FROM AUTHOR]