By selecting the daily maximum temperatures during 1961-2005 in 35 representative stations in Liaoning Province, the temporal and spatial distribution characteristics of extremely maximum temperature event were studie...By selecting the daily maximum temperatures during 1961-2005 in 35 representative stations in Liaoning Province, the temporal and spatial distribution characteristics of extremely maximum temperature event were studied. By using REOF, the mean-square deviation and so on, the variation and distribution situation of extremely maximum temperature in the different regions of Liaoning were reflected. The results showed that the extremely maximum temperature in Liaoning Province could be divided into 3 regions where were respectively the northeast area, the west and the northwest area, the south and the southeast area. The distribution characteristic of extremely maximum temperature threshold value in Liaoning Province was basically consistent with the distribution characteristic of average temperature. The zone where the extremely maximum temperature threshold was relatively high was in the northwest area of Liaoning, and the low threshold zone was in the southeast area and most areas in the east. The variation of extremely maximum temperature in winter was the greatest and in summer was the smallest. The variation of extremely maximum temperature days was the greatest in summer and wasn’t great in spring, autumn, winter.展开更多
Based on acid rain data from ten monitoring sites in Guangxi from 2003 to 2009,the temporal and spatial distribution characteristic of acid rain in Guangxi were analyzed by means of empirical orthogonal function resol...Based on acid rain data from ten monitoring sites in Guangxi from 2003 to 2009,the temporal and spatial distribution characteristic of acid rain in Guangxi were analyzed by means of empirical orthogonal function resolution(EOF).The results showed that there was fluctuating change of acid rain frequency in Guangxi,and acid rain pollution became severer in 2004-2008;acid rain frequency changed conformably in the whole region and it was obviously higher in eastern and northwestern Guangxi,while acid rain pollution became severe in western Guangxi;acid rain frequency varied out of phase between northeastern and southwestern Guangxi in an individual year.展开更多
The validity of the concept of coastal equilibritun depends upon a pnd of the ekistence of equilibrium. In addition, the methods of calculating the actual equilibrium profile and the response time are rempred. This st...The validity of the concept of coastal equilibritun depends upon a pnd of the ekistence of equilibrium. In addition, the methods of calculating the actual equilibrium profile and the response time are rempred. This study evaluates equilibriuzn conditions using evidence from EOF (empirical orthogonal function) analysis of the coased profile data (bed slopes and associated elevations) obtained from Poole and Christchurch Bays, southem England. The preliminary results show tha the larges eigenvalue is much greater than the other eigenvalues and the temporally-related eigenfunction is staionary;thes observation implies the existence of wilibrium. Further, the spatially-related eigenfunction associated with the largest eigenvalue is used to calculate the actual beach profile at equilibrium. Although the temporal eigenfopction may nuctuate, it recovers rapidly, indicating tha the response time is short. However, further studies are required to determine the response hme accurately.展开更多
A Monte Carlo experiment was done to create a statistically significant test table for selecting EOF modes whose signals are above the noise level. Numerical analysis showed that it is feasible to choose a shorter dat...A Monte Carlo experiment was done to create a statistically significant test table for selecting EOF modes whose signals are above the noise level. Numerical analysis showed that it is feasible to choose a shorter data set between temporal and spatial dimensions for conducting an EOF analysis, and thus simplify calculation of the covariance matrix and solution of its eigenvalues and eigenvectors. The experiment showed that the dominant EOF modes remained the same. This approach is more computationally efficient, reducing both computing time and computer memory requirement, while still retaining the dominant signal.展开更多
采用海河流域1956—2016年近61 a 82站逐月降水资料,通过EOF、REOF等方法分析了海河流域夏季(6—8月)降水的时空演变规律。结果表明:(1)近61a流域降水量总体空间分布特征是西北部山区偏少,东北部山前平原区偏多,流域中南部接近正常年份...采用海河流域1956—2016年近61 a 82站逐月降水资料,通过EOF、REOF等方法分析了海河流域夏季(6—8月)降水的时空演变规律。结果表明:(1)近61a流域降水量总体空间分布特征是西北部山区偏少,东北部山前平原区偏多,流域中南部接近正常年份。降水年际变化总体呈显著下降趋势,并存在20 a左右的周期波动。(2)EOF分解得到的前4个模态可以较好地反映海河流域夏季降水的4种空间分布类型,即东西反向型、南北反向型、东南—西北反向型、中部和两头反向型。REOF进一步分析显示,存在西南型、南部型、中部型。(3)EOF、REOF时间系数重点分析了第1模态,结果表明当前流域降水处于少雨年背景下的增加阶段,对应于流域降水西北部少东部多的分布型。展开更多
Based on the daily precipitation and temperature data of 97 stations in Southwest China(SW China) from1960 to 2009, a dry-wet index is calculated. The spatiotemporal variation characteristics of dry-wet conditions,pre...Based on the daily precipitation and temperature data of 97 stations in Southwest China(SW China) from1960 to 2009, a dry-wet index is calculated. The spatiotemporal variation characteristics of dry-wet conditions,precipitation and temperature are studied. Then the abnormal atmospheric circulation characteristics are discussed using reanalysis data. The results show that SW China has exhibited an overall trend of autumnal drought since the late1980 s, and this drought trend became more significant early in the 2000 s, especially in the eastern SW China. Autumnal dry-wet variation in southwestern China showed two major modes: consistent change across the entire region and opposing changes in the eastern and western regions. The spatial distribution of dry-wet anomalies was more significantly affected by precipitation, while temporal variation in dry-wet conditions was more strongly influenced by temperature. The former mode is affected by the anomalies of the precedent SST near the Western Pacific Warm Pool,the Western Pacific Subtropical High, the East Asian Trough and the South Trough. The latter mode is related to the wind anomalies in the eastern SW China and the vertical movement in the western and eastern SW China. These are the main influencing factors for the autumn dry-wet variation in SW China, which are of great significance to the prediction of drought.展开更多
The wind and temperature fields at 20 to 55 km above the Antigua launch site(17°N,61°W)were analyzed by using sounding rocket data published by the research organization on Stratosphere-Troposphere Processes...The wind and temperature fields at 20 to 55 km above the Antigua launch site(17°N,61°W)were analyzed by using sounding rocket data published by the research organization on Stratosphere-Troposphere Processes and their Role in Climate(SPARC).The results showed distinct variations in the wind and temperature fields at different heights from the 1960s to the 1990s.The overall zonal wind speed showed a significant increasing trend with the year,and the overall change in meridional wind speed showed a falling trend from 1976 to 1990,whereas the temperature field showed a significant cooling trend from 1964 to 1990.The times the trends mutated varied at different levels.By taking the altitudes at 20,35,and 50 km as representatives,we found that the zonal wind speed trend had mutated in 1988,1986,and 1986,respectively;that the meridional wind speed trend had mutated in 1990,1986,and 1990,respectively;and that the temperature trend had mutated separately in 1977,1973,and 1967,respectively.Characteristics of the periodic wind and temperature field variations at different heights were also analyzed,and obvious differences were found in time scale variations across the different layers.The zonal and meridional wind fields were basically characterized as having a significant periodic variation of 5 years across the three layers,and each level was characterized as having a periodic variation of less than 5 years.Temperature field variation at the three levels was basically characterized as occurring in 10-year and 5-year cycles.展开更多
Based on monthly runoff data of Hongjiadu,Guizhou from October 2013 to June 2015 and monthly runoff data of Yachi River,Guizhou from April 2014 to May 2015,using REOF and multiple linear regression analysis,regulation...Based on monthly runoff data of Hongjiadu,Guizhou from October 2013 to June 2015 and monthly runoff data of Yachi River,Guizhou from April 2014 to May 2015,using REOF and multiple linear regression analysis,regulation effect of water conservancy project in upper reaches of Wujiang River on monthly runoff of the river was analyzed. Seasonal temporal-spatial change of monthly runoff in Hongjiadu and Yachi River mainly contained two kinds of modalities. The first modality was that of Yachi River,which was main component of seasonal change of monthly runoff,and peak appeared in July. Space load of Yachi River modality was larger than Hongjiadu,and manual control ability of monthly runoff in Hongjiadu was larger than Yachi River. The second modality was that of Hongjiadu,and peak appeared in December. Space load of Hongjiadu modality was larger than Yachi River,and manual control ability of monthly runoff in Yachi River was larger than Hongjiadu. Seasonal changes of time components of two modalities had significant inverse phase. Regulation effect of Hongjiadu modality advanced Yachi River modality,and regulation effect of water conservancy project in Hongjiadu modality was larger than that of Yachi River modality,and seasonal distribution characteristics of regional rainfall was basically eliminated in Hongjiadu modality. Some seasonal distribution characteristics of regional rainfall were maintained in Yachi River modality. Monthly runoff modality of Yachi River had water storage regulation effect on a smaller part of regional monthly rainfall modality. Monthly runoff modality of Hongjiadu mainly had water storage regulation effect on south-north type of component of regional monthly rainfall,while most components of regional monthly rainfall modality did not have significant impact on monthly runoff modality of Hongjiadu.展开更多
This study examines the wave trains at 500 hPa occurring in East Asian summer by using the Empirical Orthogonal Function （EOF） analysis as a diagnostic tool. The results are summarized as follows： （1） A wave trai...This study examines the wave trains at 500 hPa occurring in East Asian summer by using the Empirical Orthogonal Function （EOF） analysis as a diagnostic tool. The results are summarized as follows： （1） A wave train pattern （OKJ pattern） originating from the upstream areas of the Sea of Okhotsk to the subtropical regions could display its strong signal in early and middle summer. The OKJ pattern is clearly recognized in the first EOF component in Eurasia. （2） The other wave train pattern originating fi＇om the Philippines via Japan to North America （the P-J pattern） shows quite strong signals in the whole summer. Although the P-J pattern is described as the second EOF component around the area from East Asia to Northeast Pacific Ocean, the variance contribution is the same as that of OKJ pattern in the first EOF component. （3） The composite analyses indicate that the OKJ and P-J wave trains could coexist to some extents.展开更多
Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea s...Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea surface temperature in northern Pacific are investigated using such methods as harmonic analysis, empirical orthogonal ftmction （EOF）, composite analysis and singular value decomposition （SVD）. The results show that the temporal evolution and spatial distribution of Meiyu precipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annual and inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and the monthly sea surface temperature anomalies （SSTA） lies in the west wind drift of North Pacific, which influences the precipitation anomaly of Meiyu precipitation over a key period of time from January to March in the same year. When the SST in the North Pacific west wind drift is warmer （colder） than average during these months, Meiyu precipitation anomalously increases （decreases） in the concurrent year. Results of SVD are consistent with those of composite analysis which pass the significance test of Monte-Carlo at 0.05.展开更多
To study the variations in surface hydrography and circulation in northern South China Sea (NSCS), rotated empirical orthogonal function (REOF) and extended associate pattern analysis (EAPA) are used with daily sea su...To study the variations in surface hydrography and circulation in northern South China Sea (NSCS), rotated empirical orthogonal function (REOF) and extended associate pattern analysis (EAPA) are used with daily sea surface salinity (SSS), sea surface temperature (SST) and sea surface height (SSH) datasets cover- ing 1 126 days from American Navy Experimental Real-Time East Asian Seas Ocean Nowcast System in this paper. Results show that in summer, the SCS Diluted Water Expansion (SDWE) is the most dominant factor con- trolling SSS variations in the NSCS. The remarkable SDWE usually begins in early July, reaches its maximum in middle August and weakens in late September. In summer flourishing period, its low saline core is just limited between 21°N and 22°N because of strong surface anomalous anticyclonic circulation in the NSCS. In early or late stage, the anomalous anticyclonic circulation becomes weak or turns into cyclonic one, thus the weak SCS diluted water can disperse. And its influence on the SSS variations has obviously decreased. The Kuroshio intrusion is the second controlling factor, and it has the almost opposite seasonal or intraseasonal oscillations and spatial charac- teristics to the SDWE. Winter Kuroshio Intrusion (WKI) begins in early November and lasts about three months. Intraseasonal Kuroshio Intrusion (IKI) takes place at any seasons. The westward Ekman transport produced by the north anomaly of East Asia Monsoon (EAM) pushes warmer and more saline seawater into the NSCS through the Bashi Strait and seems to decide the intensity of seasonal and intraseasonal Kuroshio intrusions.展开更多
文摘By selecting the daily maximum temperatures during 1961-2005 in 35 representative stations in Liaoning Province, the temporal and spatial distribution characteristics of extremely maximum temperature event were studied. By using REOF, the mean-square deviation and so on, the variation and distribution situation of extremely maximum temperature in the different regions of Liaoning were reflected. The results showed that the extremely maximum temperature in Liaoning Province could be divided into 3 regions where were respectively the northeast area, the west and the northwest area, the south and the southeast area. The distribution characteristic of extremely maximum temperature threshold value in Liaoning Province was basically consistent with the distribution characteristic of average temperature. The zone where the extremely maximum temperature threshold was relatively high was in the northwest area of Liaoning, and the low threshold zone was in the southeast area and most areas in the east. The variation of extremely maximum temperature in winter was the greatest and in summer was the smallest. The variation of extremely maximum temperature days was the greatest in summer and wasn’t great in spring, autumn, winter.
基金Supported by Scientific Research and Technological Development Planning Project of Guangxi Province(10123009-9)~~
文摘Based on acid rain data from ten monitoring sites in Guangxi from 2003 to 2009,the temporal and spatial distribution characteristic of acid rain in Guangxi were analyzed by means of empirical orthogonal function resolution(EOF).The results showed that there was fluctuating change of acid rain frequency in Guangxi,and acid rain pollution became severer in 2004-2008;acid rain frequency changed conformably in the whole region and it was obviously higher in eastern and northwestern Guangxi,while acid rain pollution became severe in western Guangxi;acid rain frequency varied out of phase between northeastern and southwestern Guangxi in an individual year.
文摘The validity of the concept of coastal equilibritun depends upon a pnd of the ekistence of equilibrium. In addition, the methods of calculating the actual equilibrium profile and the response time are rempred. This study evaluates equilibriuzn conditions using evidence from EOF (empirical orthogonal function) analysis of the coased profile data (bed slopes and associated elevations) obtained from Poole and Christchurch Bays, southem England. The preliminary results show tha the larges eigenvalue is much greater than the other eigenvalues and the temporally-related eigenfunction is staionary;thes observation implies the existence of wilibrium. Further, the spatially-related eigenfunction associated with the largest eigenvalue is used to calculate the actual beach profile at equilibrium. Although the temporal eigenfopction may nuctuate, it recovers rapidly, indicating tha the response time is short. However, further studies are required to determine the response hme accurately.
文摘A Monte Carlo experiment was done to create a statistically significant test table for selecting EOF modes whose signals are above the noise level. Numerical analysis showed that it is feasible to choose a shorter data set between temporal and spatial dimensions for conducting an EOF analysis, and thus simplify calculation of the covariance matrix and solution of its eigenvalues and eigenvectors. The experiment showed that the dominant EOF modes remained the same. This approach is more computationally efficient, reducing both computing time and computer memory requirement, while still retaining the dominant signal.
文摘采用海河流域1956—2016年近61 a 82站逐月降水资料,通过EOF、REOF等方法分析了海河流域夏季(6—8月)降水的时空演变规律。结果表明:(1)近61a流域降水量总体空间分布特征是西北部山区偏少,东北部山前平原区偏多,流域中南部接近正常年份。降水年际变化总体呈显著下降趋势,并存在20 a左右的周期波动。(2)EOF分解得到的前4个模态可以较好地反映海河流域夏季降水的4种空间分布类型,即东西反向型、南北反向型、东南—西北反向型、中部和两头反向型。REOF进一步分析显示,存在西南型、南部型、中部型。(3)EOF、REOF时间系数重点分析了第1模态,结果表明当前流域降水处于少雨年背景下的增加阶段,对应于流域降水西北部少东部多的分布型。
基金National Key Basic Research Development Plan(973)project(3013 CB430202)National Natural Science Foundation(41305080)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Based on the daily precipitation and temperature data of 97 stations in Southwest China(SW China) from1960 to 2009, a dry-wet index is calculated. The spatiotemporal variation characteristics of dry-wet conditions,precipitation and temperature are studied. Then the abnormal atmospheric circulation characteristics are discussed using reanalysis data. The results show that SW China has exhibited an overall trend of autumnal drought since the late1980 s, and this drought trend became more significant early in the 2000 s, especially in the eastern SW China. Autumnal dry-wet variation in southwestern China showed two major modes: consistent change across the entire region and opposing changes in the eastern and western regions. The spatial distribution of dry-wet anomalies was more significantly affected by precipitation, while temporal variation in dry-wet conditions was more strongly influenced by temperature. The former mode is affected by the anomalies of the precedent SST near the Western Pacific Warm Pool,the Western Pacific Subtropical High, the East Asian Trough and the South Trough. The latter mode is related to the wind anomalies in the eastern SW China and the vertical movement in the western and eastern SW China. These are the main influencing factors for the autumn dry-wet variation in SW China, which are of great significance to the prediction of drought.
基金supported by the National Natural Science Foundat ion of China(Grant no.41875045)
文摘The wind and temperature fields at 20 to 55 km above the Antigua launch site(17°N,61°W)were analyzed by using sounding rocket data published by the research organization on Stratosphere-Troposphere Processes and their Role in Climate(SPARC).The results showed distinct variations in the wind and temperature fields at different heights from the 1960s to the 1990s.The overall zonal wind speed showed a significant increasing trend with the year,and the overall change in meridional wind speed showed a falling trend from 1976 to 1990,whereas the temperature field showed a significant cooling trend from 1964 to 1990.The times the trends mutated varied at different levels.By taking the altitudes at 20,35,and 50 km as representatives,we found that the zonal wind speed trend had mutated in 1988,1986,and 1986,respectively;that the meridional wind speed trend had mutated in 1990,1986,and 1990,respectively;and that the temperature trend had mutated separately in 1977,1973,and 1967,respectively.Characteristics of the periodic wind and temperature field variations at different heights were also analyzed,and obvious differences were found in time scale variations across the different layers.The zonal and meridional wind fields were basically characterized as having a significant periodic variation of 5 years across the three layers,and each level was characterized as having a periodic variation of less than 5 years.Temperature field variation at the three levels was basically characterized as occurring in 10-year and 5-year cycles.
基金Supported by Doctoral Degree Construction Library of Guizhou Minzu University,Education Ministry’s New Century Excellent Talents Supporting Plan(NCET-12-0659)the China National Natural Science Foundation(31560107)+3 种基金Innovation Group Major Program of Guizhou Province(KY[2013]405,KY[2016]029)Research Projects of Guizhou Province Ministry of Science and Technology(LH[2014]7376)Research Projects of Guizhou Minzu University([2014]02)Research Projects of Guizhou Province Ministry of Education(KY[2014]266)
文摘Based on monthly runoff data of Hongjiadu,Guizhou from October 2013 to June 2015 and monthly runoff data of Yachi River,Guizhou from April 2014 to May 2015,using REOF and multiple linear regression analysis,regulation effect of water conservancy project in upper reaches of Wujiang River on monthly runoff of the river was analyzed. Seasonal temporal-spatial change of monthly runoff in Hongjiadu and Yachi River mainly contained two kinds of modalities. The first modality was that of Yachi River,which was main component of seasonal change of monthly runoff,and peak appeared in July. Space load of Yachi River modality was larger than Hongjiadu,and manual control ability of monthly runoff in Hongjiadu was larger than Yachi River. The second modality was that of Hongjiadu,and peak appeared in December. Space load of Hongjiadu modality was larger than Yachi River,and manual control ability of monthly runoff in Yachi River was larger than Hongjiadu. Seasonal changes of time components of two modalities had significant inverse phase. Regulation effect of Hongjiadu modality advanced Yachi River modality,and regulation effect of water conservancy project in Hongjiadu modality was larger than that of Yachi River modality,and seasonal distribution characteristics of regional rainfall was basically eliminated in Hongjiadu modality. Some seasonal distribution characteristics of regional rainfall were maintained in Yachi River modality. Monthly runoff modality of Yachi River had water storage regulation effect on a smaller part of regional monthly rainfall modality. Monthly runoff modality of Hongjiadu mainly had water storage regulation effect on south-north type of component of regional monthly rainfall,while most components of regional monthly rainfall modality did not have significant impact on monthly runoff modality of Hongjiadu.
基金China-Japan intergovernmental cooperation program of the JICA (2009LASWZF04)Program of Ministry of Science and Technology of China (2009DFB20540)
文摘This study examines the wave trains at 500 hPa occurring in East Asian summer by using the Empirical Orthogonal Function （EOF） analysis as a diagnostic tool. The results are summarized as follows： （1） A wave train pattern （OKJ pattern） originating from the upstream areas of the Sea of Okhotsk to the subtropical regions could display its strong signal in early and middle summer. The OKJ pattern is clearly recognized in the first EOF component in Eurasia. （2） The other wave train pattern originating fi＇om the Philippines via Japan to North America （the P-J pattern） shows quite strong signals in the whole summer. Although the P-J pattern is described as the second EOF component around the area from East Asia to Northeast Pacific Ocean, the variance contribution is the same as that of OKJ pattern in the first EOF component. （3） The composite analyses indicate that the OKJ and P-J wave trains could coexist to some extents.
基金Key National Project for Fundamental Research Project 973 (2004CB418300)Natural Science Foundation of China (40233037)
文摘Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea surface temperature in northern Pacific are investigated using such methods as harmonic analysis, empirical orthogonal ftmction （EOF）, composite analysis and singular value decomposition （SVD）. The results show that the temporal evolution and spatial distribution of Meiyu precipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annual and inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and the monthly sea surface temperature anomalies （SSTA） lies in the west wind drift of North Pacific, which influences the precipitation anomaly of Meiyu precipitation over a key period of time from January to March in the same year. When the SST in the North Pacific west wind drift is warmer （colder） than average during these months, Meiyu precipitation anomalously increases （decreases） in the concurrent year. Results of SVD are consistent with those of composite analysis which pass the significance test of Monte-Carlo at 0.05.
基金This work is supported by the Innovation Project of Chinese Academyof Sciences (KZCX3-SW-222)
文摘To study the variations in surface hydrography and circulation in northern South China Sea (NSCS), rotated empirical orthogonal function (REOF) and extended associate pattern analysis (EAPA) are used with daily sea surface salinity (SSS), sea surface temperature (SST) and sea surface height (SSH) datasets cover- ing 1 126 days from American Navy Experimental Real-Time East Asian Seas Ocean Nowcast System in this paper. Results show that in summer, the SCS Diluted Water Expansion (SDWE) is the most dominant factor con- trolling SSS variations in the NSCS. The remarkable SDWE usually begins in early July, reaches its maximum in middle August and weakens in late September. In summer flourishing period, its low saline core is just limited between 21°N and 22°N because of strong surface anomalous anticyclonic circulation in the NSCS. In early or late stage, the anomalous anticyclonic circulation becomes weak or turns into cyclonic one, thus the weak SCS diluted water can disperse. And its influence on the SSS variations has obviously decreased. The Kuroshio intrusion is the second controlling factor, and it has the almost opposite seasonal or intraseasonal oscillations and spatial charac- teristics to the SDWE. Winter Kuroshio Intrusion (WKI) begins in early November and lasts about three months. Intraseasonal Kuroshio Intrusion (IKI) takes place at any seasons. The westward Ekman transport produced by the north anomaly of East Asia Monsoon (EAM) pushes warmer and more saline seawater into the NSCS through the Bashi Strait and seems to decide the intensity of seasonal and intraseasonal Kuroshio intrusions.
