干侵入对一次东北冷涡过程的作用分析  

Analysis of Impact of Dry Intrusion on a Cold Vortex Process in Northeast China

作　　者：吴迪[1,2] 姚秀萍[2,3] 寿绍文[4] 

机构地区：[1]南京信息工程大学大气物理学院,江苏南京210044 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081 [3]中国气象局公共气象服务中心,北京100081 [4]南京信息工程大学江苏省气象灾害重点实验室,江苏南京210044

出　　处：《高原气象》2010年第5期1208-1217,共10页Plateau Meteorology

基　　金：中国气象科学研究院灾害天气国家重点实验室2008年开放基金(2008LASW-B06);国家自然科学基金项目(40875030;40875025;40775033);上海市自然科学基金项目(08ZR1422900)共同资助

摘　　要：以2006年7月20-24日一次东北冷涡过程为研究对象,利用NCEP/NCAR再分析资料、FY-2C卫星资料及常规气象观测资料,通过卫星水汽图像和大气动力场相结合的方法揭示东北冷涡过程中干侵入的特征及其对冷涡发生、发展的作用机制。结果表明,此次东北冷涡过程中干侵入特征明显,卫星水汽图像上的干侵入暗区与对流层高层的下沉运动、高值位涡、高空急流以及干冷区相对应;因干冷空气叠加在暖湿气流之上,在低层冷涡中心上空出现了对流不稳定层结,为冷涡的增强创造了有利的条件;同时,沿冷涡中心的经向垂直剖面中,高空急流入口区北侧产生的下沉运动对对流层高层低湿、高位涡的干冷空气起动力下传的作用;500 hPa绝对涡度的演变与同时刻水汽图像上干侵入区的走向、范围、强度变化相一致,由于干侵入使得冷涡中心绝对涡度增大,冷涡加强发展,因此干侵入是激发冷涡发生、发展的动力条件之一;而等熵面上各要素场的演变也能够反映出干侵入的活动特征及其对冷涡的作用。Using the NCEP/NCAR reanalysis data,FY-2C satellite and conventional meteorological observation data,the features of dry intrusion and its impacts on the formation and development of the cold vortex are explored with the methods that combined with the water vapor images and dynamic fields during 20-24 July,2006.The results show that the features of dry intrusion are obvious in the process of cold vortex.The dark zone of dry intrusion corresponds to sinking motion,high potential vorticity,upper-level jet stream and dry cold zone.Because the dry cold air superpose warm moist air,the convective instability emerges over the center of the low-level cold vortex,so it creates favorable conditions for the enhancement of cold vortex.Meanwhile,the sinking motion is generated on the north side of entrance of upper-level jet stream,which produced the function of momentum downward for dry cold air with low humidity and high potential vorticity on the upper troposphere.The evolution of 500 hPa absolute vorticity is identical with the direction,range and intensity changes of dry intrusion of the water vapor image at same time.The dry intrusion reinforces the absolute vorticity in the center of cold vortex and enhances the development of the cold vortex,so it is one of the driving force to promote the development of the cold vortex.The element fields on the isentropic surface can reflect the features of dry intrusion and its mechanism to the cold vortex.

关 键 词：东北冷涡 干侵入 水汽图像 位涡 

分 类 号：P458[天文地球—大气科学及气象学]