Using the NCEP reanalysis at 1°×1° resolution in conjunction with satellite imagery,a study is undertaken of easterly wave related rainstorm events on August 3~4,2001 in seaboards between northern Fujian and southern Zhejiang,expounding the scheme for computing helicity,and exploring the rainstorm evolution and the genesis of the Yandang mountains-triggered a meso-vortex(Duan and Chen,2005) by means of helicity and Q vector divergence.Besides,MM5V2 is employed to simulate the easterly wave caused meso-vorte...
ZHENG Feng1-3(1.Chinese Academy of Meteorological Sciences,Beijing 100081,China
In order to investigate the different thermodynamic mechanisms between rapid intensifying （RI） and rapid weakening （RW） tropical cyclones （TCs）, the thermodynamic structures of two sets of composite TCs are analyzed based on the complete-form vertical vorticity tendency equation and the NCEP/NCAR reanalysis data. Each composite is composed of five TCs, whose intensities change rapidly over the coastal waters of China. The results show that the maximum apparent heating source Q1 exists in both the upper and lower troposphere near the RI TC center, and Q1 gets stronger at the lower level during the TC intensification period. But for the RW TC, the maximum Q1 exists at the middle level near the TC center, and Q1 gets weaker while the TC weakens. The maximum apparent moisture sink Q2 lies in the mid troposphere. Q2 becomes stronger and its peak-value height rises while TC intensifies, and vice versa. The increase of diabatic heating with height near the TC center in the mid-upper troposphere and the increase of vertical inhomogeneous heating near the TC center in the lower troposphere are both favorable to the TCs＇ rapid intensification; otherwise, the intensity of the TC decreases rapidly.
