Toward a refined estimation of typhoon wind hazards: Parametric modeling and upstream terrain effects

Parametric and stochastic typhoon model enable a rapid estimation of wind hazards in typhoon-prone regions. It always needs a large amount of historical track information to develop the track, intensity as well as wind field parameters. This study describes a technique for estimating two commonly used typhoon wind field parameters, i.e. R-max,R-s and B-s using the observed wind information from the best track dataset coupled with a semi-analytical wind field model. At each timestep of every typhoon event, the radial wind speed profile is well reproduced with an optimal pair of R-max,R-s and B-s. The correlation analyses of R-max,R-s and B-s with other parameters are conducted. The R-max,sand B-s at different timesteps allows the development of recursive models accounting for their auto correlations between adjacent timesteps. Linearly weighted progressive formulas of R-max,R-s and Bs using all data extracted in the Western Pacific domain are developed. This idea is similar to the track and intensity models during stochastic typhoon simulations, which provides a forward step towards the more rational estimation of typhoon hazards. Moreover, the typhoon-event-specific R-max,R-s and B-s enables the reconstruction of historical wind hazards. By introducing the underlying terrain effects on wind speeds in terms of a directional roughness length and a topographic speed-up factor, 184 observed landed or offshore typhoon-scale storms along the China coastline from 1977 to 2015 are investigated. A dataset regarding the wind hazard footprints for over-water, roughness only and roughness and topography combined conditions of these 184 storms is developed to facilitate risk assessment and disaster mitigation during typhoon events.

Automated summary

By utilizing historical track information and a semi-analytical wind field model, this study develops recursive models and weighted formulas to improve the estimation of typhoon hazards. Furthermore, considering the effects of underlying terrain on wind speeds, a dataset for risk assessment and disaster mitigation during typhoon events is established to investigate 184 observed storms along the China coastline from 1977 to 2015.