In this paper,the concept of stationary-wave nonstationarity is presented and elucidated in the framework of the Lorenz circulation decomposition.This concept indicates the relative magnitude of the zonal nonuniform a...In this paper,the concept of stationary-wave nonstationarity is presented and elucidated in the framework of the Lorenz circulation decomposition.This concept indicates the relative magnitude of the zonal nonuniform abnormity to the intensity of stationary waves on the monthly mean scale.Based on the Lorenz circulation decomposition,the nonstationarity degree I_（us）（I_（us）~1） of the global（local） stationary waves is defined,and then used to analyze the stationary-wave nonstationarity at 30°-60°N,where the intensity of stationary waves at 500 hPa in the Northern Hemisphere,as is well known,is very high.The following findings are obtained：（1） There exist seasonal southward and northward movements in the position of the nonstationarity zones of the global stationary waves.The steady stationary waves occur in midlatitudes （35°-55°N） in winter and in the subtropical region（south of 35°N） in summer,associated with the major troughs over East Asia and North America and the weak European trough in winter,and with the relatively steady subtropical high system in summer.A high value center of I_（us） is at 35°N in spring and 50°N in summer,which might be caused by the seasonal variation of stationary-wave intensity,particularly in association with the interannual variability of trough/ridge positions of stationary waves on the monthly mean maps.（2） There exists obvious asymmetry in I_（us）~1,with the steady zones always located in the areas controlled by strong troughs/ridges and the unsteady ones in the areas where the stationary-wave intensity is low.The I_（us）~1 in the subtropics（south of 35°N） is larger in winter than in summer,and vice versa in the midlatitude region（north of 35°N）.The summertime distribution of I_（us）~1 on the whole shows a rather complicated structure.However,North Europe is the most unsteady area for local stationary waves,as represented by high values of I_（us）~1 in both summer and winter,while over the North American continent �展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.40633018
文摘In this paper,the concept of stationary-wave nonstationarity is presented and elucidated in the framework of the Lorenz circulation decomposition.This concept indicates the relative magnitude of the zonal nonuniform abnormity to the intensity of stationary waves on the monthly mean scale.Based on the Lorenz circulation decomposition,the nonstationarity degree I_（us）（I_（us）~1） of the global（local） stationary waves is defined,and then used to analyze the stationary-wave nonstationarity at 30°-60°N,where the intensity of stationary waves at 500 hPa in the Northern Hemisphere,as is well known,is very high.The following findings are obtained：（1） There exist seasonal southward and northward movements in the position of the nonstationarity zones of the global stationary waves.The steady stationary waves occur in midlatitudes （35°-55°N） in winter and in the subtropical region（south of 35°N） in summer,associated with the major troughs over East Asia and North America and the weak European trough in winter,and with the relatively steady subtropical high system in summer.A high value center of I_（us） is at 35°N in spring and 50°N in summer,which might be caused by the seasonal variation of stationary-wave intensity,particularly in association with the interannual variability of trough/ridge positions of stationary waves on the monthly mean maps.（2） There exists obvious asymmetry in I_（us）~1,with the steady zones always located in the areas controlled by strong troughs/ridges and the unsteady ones in the areas where the stationary-wave intensity is low.The I_（us）~1 in the subtropics（south of 35°N） is larger in winter than in summer,and vice versa in the midlatitude region（north of 35°N）.The summertime distribution of I_（us）~1 on the whole shows a rather complicated structure.However,North Europe is the most unsteady area for local stationary waves,as represented by high values of I_（us）~1 in both summer and winter,while over the North American continent �
