Reconstruction of radial parametric pressure field near ground surface of landing typhoons in Northwest Pacific Ocean

Abstract

The radial distribution of environmental pressure near the ground surface during typhoons is an initial input condition for height-resolving typhoon modeling widely used as a practical and relatively accurate method for rapid assessment of typhoon-induced natural hazards and wind-resistant design of structures. The radius to maximum wind speed Rmax and radial pressure distribution parameter βs, (usually named the Holland power exponent of atmospheric pressure) are two key pressure field parameters that fundamentally determine the parametric typhoon pressure field and collocated wind velocity field. Observations from the Joint Typhoon Warning Center (JTWC) show that Rmax follows a lognormal distribution and has strong correlation with central pressure difference Δps and typhoon center latitude ψ. However, it is still hard to satisfactorily reproduce the landing typhoon environmental pressure. By employing near-ground environmental pressure data involving several hundreds of meteorological stations distributed in coastline regions of the Northwest Pacific Ocean, evolution of typical environmental pressures during four strong typhoons, Khanun (0515), Wipha (0713), Krosa (0716) and Morakot (0908), have been recorded in Southeast China. Finally, a novel technique for modeling the radial surface pressure model is proposed utilizing an appropriate model for radius to maximum winds Rmax. The variation characteristics for directions, landfall states and probability distributions of βs are compared and discussed, and then probability correlations among βs and Rmax, Δps, ψ are fitted and validated, showing that the statistical correlation function model is obviously different from former formulations and is more suitable for rebuilding a wind velocity field, especially near the ground surface after typhoon landfalls along the southeast coastlines of China, which are typhoon-prone hazard regions during moving typhoons.