CAUSAL ANALYSIS AND NUMERICAL MODELING OF THE INSHORE INTENSIFICATION OF SUPER TYPHOON 'HATO'

Abstract:

This paper comprehensively analyzes the characteristics and cause of the inshore intensification of super typhoon "Hato", the 13th super typhoon in 2017. The aspects of typhoon structure, evolution of large-scale circulation and physical quantity field are analyzed using observation data from the Guangdong Automatic Station, Shenzhen Doppler Radar data, NCEP 1°×1° reanalysis data, NCEP 0.25°×0.25° sea surface temperature (SST) data, etc. Additionally, in order to investigate the influence of SST change on the intensity of "Hato", the WRF model and ECMWF 0.125°×0.125° reanalysis data are combined to conduct 3 sensitivity tests on "Hato". The results show that the favorable conditions for inshore intensification of "Hato" included: the strengthening and westward extension of the subtropical high, continuous increase of low level moisture transport, an anomalous warm SST area north of 20°N in the South China Sea, an extreme divergence value in the northern South China Sea exceeding 6×10-5s-1, and vertical environmental wind shear between 1.1m/s-4.8m/s. The intensity of "Hato" was very sensitive to changes in SST. When the SST rose or dropped by 2°C, the minimum central pressure of the typhoon changed by about 13hPa or 11hPa, respectively. SST indirectly influenced the intensity of the typhoon through affecting latent heat transport and sensible heat transport.