Based on the temperature of the black body (TBB),station observed and NCEP reanalysis data,the impacts of the eastward propagation of convective cloud systems over the Tibetan Plateau on the southwest vortex (SWV) for...Based on the temperature of the black body (TBB),station observed and NCEP reanalysis data,the impacts of the eastward propagation of convective cloud systems over the Tibetan Plateau on the southwest vortex (SWV) formation that occurred at 1800 UTC on 29 June 2003 are analyzed by using the Zwack-Okossi (Z-O) equation to diagnose the thermal and dynamic processes.It is found that,in summer,severe convective activities often occur over the Tibetan Plateau due to the abundant supply of moisture.The convective cloud near the east edge of the plateau could move eastward with a shortwave trough in the westerly.The divergent center that is induced by latent heat release,which is associated with severe convective activities,moves out with the convective cloud and contributes to the low level decompression which is favorable for the formation of plateau edge cyclogenesis (PEC).The Z-O equation indicates that,in this case,the latent heat release and convergence are the two most important factors for SWV formation,which amounts to about 42% and 15% of the term TOTAL,respectively.It is implied that the thermal process effect was more important than the dynamic process during SWV formation.展开更多
Based on the 6-hour-interval reanalysis data with 1°× 1°resolution from the National Center for Environmental Prediction/the National Center for Atmospheric Research （NCEP/NCAR）, the eddy kinetic ener...Based on the 6-hour-interval reanalysis data with 1°× 1°resolution from the National Center for Environmental Prediction/the National Center for Atmospheric Research （NCEP/NCAR）, the eddy kinetic energy （EKE） budget of a southwest vortex （SWV） that caused heavy rainfall in Guangxi over South China （from 1200 UTC 11 to 0000 UTC 13 June） is calculated. The results are as follows： （a） The SWV is a kind of subtropical vortex, with characteristics of both an extratropical vortex and a tropical vortex. （b） In the case examined, large-scale circulation and other perturbation fields contributed to the formation and development of the SWV. （c） When the SWV moved from weak large-scale circulation EKE areas to strong ones, the EKE of the SWV increased, and vice versa. （d） Sub-grid processes and frictional dissipation were the main sinks of the SWV EKE, which contributed to the decay of the SWV. （e） The residual term （RES） and the Total （composite effect of all right hand side （rhs） terms except the RES in the EKE equation） varied almost in the same tendency, which kept the EKE varying in a moderate way. （f） The EKE between 550 hPa and 850 hPa increased most intensively, corresponding to the vertical stretching of the SWV.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 40875021 and 40930951)the project of the State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences (Grant No. 2009LASW-A03)
文摘Based on the temperature of the black body (TBB),station observed and NCEP reanalysis data,the impacts of the eastward propagation of convective cloud systems over the Tibetan Plateau on the southwest vortex (SWV) formation that occurred at 1800 UTC on 29 June 2003 are analyzed by using the Zwack-Okossi (Z-O) equation to diagnose the thermal and dynamic processes.It is found that,in summer,severe convective activities often occur over the Tibetan Plateau due to the abundant supply of moisture.The convective cloud near the east edge of the plateau could move eastward with a shortwave trough in the westerly.The divergent center that is induced by latent heat release,which is associated with severe convective activities,moves out with the convective cloud and contributes to the low level decompression which is favorable for the formation of plateau edge cyclogenesis (PEC).The Z-O equation indicates that,in this case,the latent heat release and convergence are the two most important factors for SWV formation,which amounts to about 42% and 15% of the term TOTAL,respectively.It is implied that the thermal process effect was more important than the dynamic process during SWV formation.
基金supported by the National Natural Science Foundation of China under Grant Nos. 40875021 and 40605016the foundation of the Institute of Heavy Rain, Wuhan under Grant No. IHR2007K05
文摘Based on the 6-hour-interval reanalysis data with 1°× 1°resolution from the National Center for Environmental Prediction/the National Center for Atmospheric Research （NCEP/NCAR）, the eddy kinetic energy （EKE） budget of a southwest vortex （SWV） that caused heavy rainfall in Guangxi over South China （from 1200 UTC 11 to 0000 UTC 13 June） is calculated. The results are as follows： （a） The SWV is a kind of subtropical vortex, with characteristics of both an extratropical vortex and a tropical vortex. （b） In the case examined, large-scale circulation and other perturbation fields contributed to the formation and development of the SWV. （c） When the SWV moved from weak large-scale circulation EKE areas to strong ones, the EKE of the SWV increased, and vice versa. （d） Sub-grid processes and frictional dissipation were the main sinks of the SWV EKE, which contributed to the decay of the SWV. （e） The residual term （RES） and the Total （composite effect of all right hand side （rhs） terms except the RES in the EKE equation） varied almost in the same tendency, which kept the EKE varying in a moderate way. （f） The EKE between 550 hPa and 850 hPa increased most intensively, corresponding to the vertical stretching of the SWV.
