Analyses And Numerical Modeling Of A Pair Of Cyclones Over The Southern Ocean In November 2004

In this thesis, the structures of a pair of cyclones, named as M and N, respectively which occurred over the southern oceans in November 2004 and had significant impacts on the navigation of Chinese research vessel Xuelong are investigated by using almost all the available observational data, including FNL ( Final Analysis) data issued by NCEP (National Centers for Environmental Prediction), GOES ( Geostationary Operational Environmental Satellite)-9 infrared satellite imagery, sounding data and QuickSCAT(Quick Scatterometer) wind data issued by NASA (National Aeronautics and Space Administration), and high-resolution simulation results of WRF (Weather Research Forecast ) modeling.Firstly, the synoptic situation and the evolutionary processes of this pair of cyclones are described based upon FNL data and GOES-9 satellite imagery. Then, preliminary analyses of the vertical structures of this pair of cyclones are performed. Finally, the detailed vertical structures, as well as the development mechanism of this pair of cyclones are analyzed.After its generation, the parent cyclone M moved southeastward along clockwise spiral line, and retreated westward after it achieved its mature stage. When the parent cyclone M was at its dissipation phase, the child cyclone N generated in the northern part of the M low-pressure system. Thus the system of a pair of cyclones formed. Then N and M moved clockwise twisting with each other. The parent cyclone M gradually weakened, and moved to the northeast along a clockwise spiral path. The child cyclone N rapidly developed while moved southeastward, under the combined effect of the positive vorticity advection near the center and the warm advection which increased with height. M died out when it completed the circle clockwise track. Then N reached the mature stage and then gradually weakened moving to the Antarctic continent.These two cyclones had distinct"warm core"and"wet-core"structures. The maximum vorticity appeared at the southwestern parts of the cyclone M and N. Cyclone N had a much stronger baroclinicity accompanied with a distinct spiral-shaped cloud pattern with several spiral cloud walls around the"eye"at satellite image. There were warm and wet air at the eastern part of these two cyclones while they enhanced, transporting heat and water vapor to the polar region. Finally the structures of this pair of cyclones were compared.