Kinetic Energy Budegt Analysis of Tropical Cyclogenesis Precursors in the Monsoon Trough
Tropical cyclones always occur in a synoptic-scale disturbance.By using NCEP/NCAR FNL data,tropical cyclogenesis precursors in the monsoon trough from 11 August to l0 September 2004 were chosen.Through calculating the kinetic energy budget,we analyzed the development of the tropical cyclogenesis precursors.Aside from Chaba,others all formed in the cyclonic circulation of the northwestward-propagating synoptic-scale wave trains.The cyclonic circulation can couple with the northeastsouthwest-titled anticlockwise circulation of the westward-propagating MRG wave.Kinetic energy budegt analysis reveals that kinetic energy of tropical cyclogenesis precursors increased before 12-72 hours prior to the formation of the tropical depression.Local convergence of the eddy geopotential flux was the dominant term.When the precursor first appeared at the far eastern end of the monsoon trough,energy accumulation was also a main factor for disturbance development.As the disturbance moved northwestward and entered the monsoon shear region,barotropic energy conversion by the meridional gradient of the basic zonal flow was indeed another important energy source.For the case of Sarika,it formed when the MT westward retreated.The nolinear term played another important role for this disturbance development.
国家科技期刊平台
NSTL
万方数据
维普
