摘要
Based on observations and reanalysis data,the characteristics of the evolution of climatological spring precipitation over Southern China(SPSC) and the associated climatological intraseasonal oscillation(CISO) and atmospheric circulation are studied.Results show that SPSC increases in an oscillatory way.Although the evolution of SPSC is similar in different regions,there are also differences.In different regions of Southern China,the onset dates of the rain season are from the 12 th to 24 th pentad and the peak dates are after the 20 th pentad.CISO is an important component of SPSC,which is not only statistically significant,but also accompanies a dynamically coherent structure.The peak wet/dry phase of each CISO cycle corresponds to a significant rainfall increasing/decreasing period and modulates the evolution of SPSC.The rainfall growth in the second half of March and mid-April is the result of the modulation.The wet/dry phase of CISO is accompanied by low-level convergent(upper-level divergent) and cyclonic(anti-cyclonic) circulation,which favors ascending motion to develop over Southern China.
Based on observations and reanalysis data,the characteristics of the evolution of climatological spring precipitation over Southern China（SPSC） and the associated climatological intraseasonal oscillation（CISO） and atmospheric circulation are studied.Results show that SPSC increases in an oscillatory way.Although the evolution of SPSC is similar in different regions,there are also differences.In different regions of Southern China,the onset dates of the rain season are from the 12 th to 24 th pentad and the peak dates are after the 20 th pentad.CISO is an important component of SPSC,which is not only statistically significant,but also accompanies a dynamically coherent structure.The peak wet/dry phase of each CISO cycle corresponds to a significant rainfall increasing/decreasing period and modulates the evolution of SPSC.The rainfall growth in the second half of March and mid-April is the result of the modulation.The wet/dry phase of CISO is accompanied by low-level convergent（upper-level divergent） and cyclonic（anti-cyclonic） circulation,which favors ascending motion to develop over Southern China.
基金
National Program for Key Fundamental Research and Development(2012CB417205)
International Cooperation Project for Ministry of Science and Technology(2009DFA23010)
National Project for Science and Technology Support(2009BAC51B)
Project of Science and Technology for Guangdong Province(Meteorological Sector)(200905)
National Natural Science Foundation of China(41205069)
