利用地面气象站和探空观测资料,对2013年8月16日辽宁地区特大暴雨过程数值模式预报的产品进行检验和对比分析,主要包括降水、500 h Pa位势高度场和副热带高压指数等。结果表明:一般性降水预报准确率T639模式整体优于EC模式,暴雨预报平...利用地面气象站和探空观测资料,对2013年8月16日辽宁地区特大暴雨过程数值模式预报的产品进行检验和对比分析,主要包括降水、500 h Pa位势高度场和副热带高压指数等。结果表明:一般性降水预报准确率T639模式整体优于EC模式,暴雨预报平均准确率EC模式略高于T639模式,T639模式和EC模式降水预报正负距平出现位置近似。多个数值模式对清原站主要降水时段(8月16日11—23时)的降水预报明显偏弱,WRF模式预报的全省3 h最大降水量远大于实况,T639模式和EC模式预报的降水量级均明显小于实况。EC模式和多模式集成72 h内降水落区与强降水中心位置的预报相对较稳定,过去15 d的滑动平均检验结果对降水预报具有一定的指示意义,72 h内EC模式的特征线预报一致性明显高于T639模式,对于辽宁省大部地区及上游高空槽附近EC模式降水预报的离散度小于T639模式。展开更多
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 （about 120°E-60°W）,the I_（us）~1 is slightly less than 1 in summer,indicating that the stationary waves in this region are more steady than those over other mid and high latitude regions.（3） From North China to Northwest Pacific,there is a high value zone of I_（us）~1 in summer,with its center（45°N,130°E） located in the east of Heilongjiang Province.This influences the summer climate of northern China,including Northeast, North,and Northwest China.It is obvious that the nonstationarity is an intrinsic attribute of stationary waves,and can be regarded as being of the same importance as the intensity and energy-spectrum structure of stationary waves in the studies of the general circulation system.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 （about 120°E-60°W）,the I_（us）~1 is slightly less than 1 in summer,indicating that the stationary waves in this region are more steady than those over other mid and high latitude regions.（3） From North China to Northwest Pacific,there is a high value zone of I_（us）~1 in summer,with its center（45°N,130°E） located in the east of Heilongjiang Province.This influences the summer climate of northern China,including Northeast, North,and Northwest China.It is obvious that the nonstationarity is an intrinsic attribute of stationary waves,and can be regarded as being of the same importance as the intensity and energy-spectrum structure of stationary waves in the studies of the general circulation system.
