The dimensions of attractors and predictability are estimated from phase space trajectories of observed 500 hPa height over the Northern Hemisphere. As a first estimate the dimensions of attractors are about 11.5 and ...The dimensions of attractors and predictability are estimated from phase space trajectories of observed 500 hPa height over the Northern Hemisphere. As a first estimate the dimensions of attractors are about 11.5 and the doubling time of the initial error is 6 to 7 days for original data. But the former is shorter and the latter is longer for low frequency data set.To verify if the predictability estimated by this method and by general circulation model is identical, the doubling time of the initial error of a model data set by both methods is estimated. It is shown that the predictability obtained from phase space trajectories is overestimated to sufficient small initial error. But it is underestimated to the time being equal to the climatological RMS error.展开更多
The paper is to depict the major structures of the Northern Hemispheric summer sealevel pressure (SLP), 500 hPa height (H 500) and 500 hPa ridge-and-trough (RAT) field during1951-1980. The 1960s’ jump was found in th...The paper is to depict the major structures of the Northern Hemispheric summer sealevel pressure (SLP), 500 hPa height (H 500) and 500 hPa ridge-and-trough (RAT) field during1951-1980. The 1960s’ jump was found in the major signal of each field as well as inthe series of many circulation parameters. The major part of the H 500 change was the heightlowering over the most of the Hemisphere during the 1960s, corresponding well to the sur-face temperature change. The SLP and RAT changed in a way similar to that of the rainfallchange, with regard to the southwest-to-northeast zonal structure in the geographical distri-butions of the major signals of all the three fields. The relationship between the changes ofsome circulation parameters and the regional rainfall is discussed.展开更多
[ Objective] The research aimed to analyze extreme circulation characteristics at 500 hPa of height field in Eurasian region in recent 20 years. [ Method ] Based on NCEP/NCAR reanalysis daily data at 500 hPa of height...[ Objective] The research aimed to analyze extreme circulation characteristics at 500 hPa of height field in Eurasian region in recent 20 years. [ Method ] Based on NCEP/NCAR reanalysis daily data at 500 hPa of height field from 1961 to 2009 of Eurasia （15° -80° N, 40° -150° E）, seasonal and monthly change situations of extreme circulation in Eurasia were studied by the method of climatologically equally likely intervals （ CE- Ll）. [Result] Growth rate of extremely low circulation increased in Eurasia in the last 20 years, but the rise amplitude was smaller. In the middle of China and Mongolia, grow rate change of extremely low circulation was the smallest. The growth rates of extremely high circulation in spring, au- tumn and winter gradually decreased as latitude rose. The maximum growth rate of extremely high circulation in summer was in Qinghai -Tibet Plat- eau, which corresponded with the climate characteristics of summer subtropical high going northward and then retreating southward. By contrasting the growth rates of extremely low and high circulation, it was clear that the growth rate of high circulation was higher than that of the low circulation. [Conusion] The research could be as a reference for studying change characteristics of the extreme climate event in China.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
文摘The dimensions of attractors and predictability are estimated from phase space trajectories of observed 500 hPa height over the Northern Hemisphere. As a first estimate the dimensions of attractors are about 11.5 and the doubling time of the initial error is 6 to 7 days for original data. But the former is shorter and the latter is longer for low frequency data set.To verify if the predictability estimated by this method and by general circulation model is identical, the doubling time of the initial error of a model data set by both methods is estimated. It is shown that the predictability obtained from phase space trajectories is overestimated to sufficient small initial error. But it is underestimated to the time being equal to the climatological RMS error.
文摘The paper is to depict the major structures of the Northern Hemispheric summer sealevel pressure (SLP), 500 hPa height (H 500) and 500 hPa ridge-and-trough (RAT) field during1951-1980. The 1960s’ jump was found in the major signal of each field as well as inthe series of many circulation parameters. The major part of the H 500 change was the heightlowering over the most of the Hemisphere during the 1960s, corresponding well to the sur-face temperature change. The SLP and RAT changed in a way similar to that of the rainfallchange, with regard to the southwest-to-northeast zonal structure in the geographical distri-butions of the major signals of all the three fields. The relationship between the changes ofsome circulation parameters and the regional rainfall is discussed.
文摘[ Objective] The research aimed to analyze extreme circulation characteristics at 500 hPa of height field in Eurasian region in recent 20 years. [ Method ] Based on NCEP/NCAR reanalysis daily data at 500 hPa of height field from 1961 to 2009 of Eurasia （15° -80° N, 40° -150° E）, seasonal and monthly change situations of extreme circulation in Eurasia were studied by the method of climatologically equally likely intervals （ CE- Ll）. [Result] Growth rate of extremely low circulation increased in Eurasia in the last 20 years, but the rise amplitude was smaller. In the middle of China and Mongolia, grow rate change of extremely low circulation was the smallest. The growth rates of extremely high circulation in spring, au- tumn and winter gradually decreased as latitude rose. The maximum growth rate of extremely high circulation in summer was in Qinghai -Tibet Plat- eau, which corresponded with the climate characteristics of summer subtropical high going northward and then retreating southward. By contrasting the growth rates of extremely low and high circulation, it was clear that the growth rate of high circulation was higher than that of the low circulation. [Conusion] The research could be as a reference for studying change characteristics of the extreme climate event in China.
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.
