Abstract:
Based on NCEP/NCAR (11) reanalysis data,the pattern of the landing storms of the bay of Bengal in northeast path by comparative and composite analysis from 2001 to 2010 has been analyzed.The results show that the consistency cyclonic inflow layer of storm center is limited to 900 hPa below.The thickness of the annular complex zone reduces with storms landfall.The vertical circulation of storms shows asymmetry,and the layer of air outflow in west of storms is higher but the layer of it in east is lower.The south and north of storms is northward,and the vertical updraft speed in central and peripheral of them is greater than that of other areas.The vortex structure of storms is basic symmetry and the vortex column in entire troposphere is vertical.The vortex feature of storms changes from circularto ovalfrom landing prior to landing.Before landing,the structure of convergence at the bottom layer and divergence at the high level in the troposphere over the center of storms around is weak.The structure of convergence and divergence at middle-high level of troposphere along both sides of storms is asymmetric.Bengal storms survival environment presents smaller vertical wind shear,larger gradient changes regional,and storms move along maximum vertical wind shear gradient direction.