An information exchange framework between physical modeling and numerical simulation to advance tropical cyclone boundary layer predictions

Our previous findings (Tse et al., 2014) suggest that both the physical and numerical simulations of a tropical cyclone boundary layer can be improved by information exchanges. In the present study, the improvements are quantitatively measured. For one thing, the approaching wind flow adopted in a wind-tunnel topographic study is adjusted according to the mean wind profile extracted from a meso-scale meteorological simulation of Typhoon Fengshen (2008) for a particular period, during which the observed wind direction indicated the sea-fetch wind flow. For another thing, the measurements obtained in a wind-tunnel topographic study are processed and used to improve the meso-scale meteorological simulation through observation nudging. Comparisons with the field-measurements taken at a main weather station and several auxiliary weather stations reveal that both the numerical and the physical simulations are improved. Specifically, the super-gradient flow—observed at the weather stations but not in the conventional wind-tunnel topographic study—is successfully simulated in the improved wind-tunnel test. The wind tunnel measurements, which more accurately reflect the influence of the underlying terrain, are incorporated into the meso-scale meteorological simulation of Typhoon Fengshen (2008). The simulation yields the results in better agreement with the field-measurements of the relative strength of wind speeds, with the exception of the wind strengths at mountain-summit points.