'0801南方雪灾'与同期蒙古高压中期活动的关系

摘要

用1951-2008年58 a1月10日-2月2日1000 hPa高度场逐日NCEP/NCAR再分析格点资料,求得逐日蒙古高压的强度P和中心位置λ_c,φ_c指数,用其对"0801南方雪灾"期间蒙古高压的中期演变过程进行统计分析.结果表明,2008年1月10日-2月2日蒙古高压强度P和中心所在纬度φ_c出现了连续4次振荡,它们与我国南方降温、降水振荡过程准同步.由P、(λ_c,φ_c)给出的综合动态图上蒙古高压4次活动过程也很明显地与降温、降水中期过程一一对应.分析表明2008年1月10日-2月2日蒙古高压的这一中期演变特征,是1951年以来仅有的一次.因此,可以认为,在充沛水汽供应条件下蒙古高压强而连续的爆发是导致"0801南方雪灾"产生的直接环流成因.%By using the 1000 hPa geopotential height grid data during the 10 January--2 February in 1951—2008(from the NCEP／NCAR daily reanalysis dataset)，a set of circulation indices are calculated to statistically analyze the medium—term processes of the Mongolian high during the“0801 snow storm over southern China”period，including indices of the intensity P and centre position(λ_c,φ_c)of the high．The results show that the P and φ_c of Mongolian high had four consecutive oscillations during rnthe period of 10 January-2 February 2008，which quasisynchronously related to the four medium—term rnprocesses of temperature fall and precipitation over southern China．On the composite dynamic diagram of P and(λ_c,φ_c)，the four active processes of Mongolian high corresponded well with four mediumterm temperature fall and precipitation oscillations．This unique characteristic of the medium—term development of Mongolian high has been shown only once since 1951．Therefore，under the condition of abundant water vapor supply，it is the strong and continuous outbreaks of Mongolian high that directly rncaused the“0801 snow storm over southera China”．