| For the super typhoon Maria from July 4 to July 11,2018,we carry out mesoscale numerical simulation with the help of methods of meteorology-statistic diagnosis,dynamic analysis,sensitivity experiment,etc to carry out systematic research on the internal process and external environmental elements before and during the rapid intensification period.1)The characteristics of the inner-core convective bursts(CBs)and its relationship with the rapid intensification of tropical cyclone Maria are analyzed.It is different from the CBs in the entire inner-core that have been studied in previous studies.In distinct shear-relative quadrants,instead of the overall inner-core CBs frequently used,presents cyclonic rotation from downshear to upshear quadrants during RI,producing a higher efficiency for tropical cyclone(TC)spinup,which accelerates the RI process.The sudden increase of CBs and the accompanying latent heat heating provide a indicator for rapid intensification of Maria.2)We find that before Maria rapid intensification,the isentropic surface drops sharply from the horizontal and the horizontal gradient increases by analyzing the structure of the upper-tropospheric warm core and its effect on the rapid intensification process.By calculating the static pressure drop caused by the upper-tropospheric warm core,its contribution to the rapid intensification of the typhoon is quantified.And we find that the contribution rate of the upper-tropospheric warm core to the pressure drop is absolutely dominant relative to the abnormal of the middle and low layers below the warm core.3)The effect of the sea surface temperature(SST)gradient effect on the rapid intensification of the typhoon was studied.We found that the path and intensity of the typhoon and the rapid intensification process responded more significantly to changes in the SST meridional gradient.We found that the Lagrangian path calculated by the steering flow is basically consistent with the path of the four sensitivity experiment,which could explain the path deviation relative to the basic simulation experiment.4)Based on the analysis of convective bursts and latent heat heating,warm core structure and potential temperature adjustment,a new mechanism for synergistic multi-process leading to rapid intnesification of typhoon is condensed: the latent heat release of convective bursts is transferred downward through the center of the potential temperature adjustment together with the compensatory subsidence and temperature increase of the stratosphere,a upper-tropospheric warm core structure is formed.Its high heating efficiency causes the static pressure to drop sharply,which leads to rapid intensification of typhoon,which enhances the new understanding of the rapid intensification mechanism of typhoons.Through this study,we finally obtained a new understanding of some internal thermodynamic structural features before and during the rapid strengthening process of tropical cyclone Maria,obtained some predictive signal features,and deepened the rapid intensification mechanism of tropical cyclones understanding. |
