根据1958-2011年中国东部（105°E以东）316站逐日降水资料及NCEP/NCAR逐日再分析资料,利用统计分析、物理量诊断等方法,探讨北方雨季（7月11日至8月31日）中国东部降水异常模态及同期、前期的大气环流特征。分析发现,北方雨季中国...根据1958-2011年中国东部（105°E以东）316站逐日降水资料及NCEP/NCAR逐日再分析资料,利用统计分析、物理量诊断等方法,探讨北方雨季（7月11日至8月31日）中国东部降水异常模态及同期、前期的大气环流特征。分析发现,北方雨季中国东部降水异常表现为三个相互独立的降水模态：第一模态为偏西型,当其时间系数为正（负）时,河套地区降水偏多（少）,江淮流域上游降水偏少（多）,南方大部降水偏多（少）;第二模态为北方一致型,当其时间系数为正（负）时,北方降水一致偏多（少）,长江流域降水偏少（多）;第三模态为偏东型,当其时间系数为正（负）时,东北南部至长江中游降水偏多（少）,华东沿海降水偏少（多）。研究发现,造成北方雨季三个降水异常模态的环流特征各不相同：偏西型降水主要受西亚高空副热带西风急流位置南北偏移影响;北方一致型降水主要由东亚—太平洋遥相关波列导致;偏东型降水主要与海陆气压异常对比造成的东亚夏季风变化有关。此外,三个模态与前期环流异常有密切联系。第一模态的正（负）异常由7月上旬200 h Pa来自北大西洋的异常波列造成乌拉尔山位势高度负（正）异常和巴尔喀什湖以南位势高度正（负）异常引起。第二模态的正（负）异常与前期7月上旬200 h Pa北大西洋上位势高度负（正）异常产生的沿中纬度（高纬度）路径向下游传播的波列有关。第三模态的正（负）异常由春季3月份低层蒙古上空异常的气旋（反气旋）持续至同期造成。展开更多
The analysis of '09.08.19' regional rainstorm weather in Shenyang showed that the circulation situation of the rainfall was the typical subtropical high pressure with westerly trough.Surface cyclone developmen...The analysis of '09.08.19' regional rainstorm weather in Shenyang showed that the circulation situation of the rainfall was the typical subtropical high pressure with westerly trough.Surface cyclone development in cooperation with the convergence and the role of the front of the uplift produced by the heavy rains trigger mechanism.The coupling configuration of low-level jet created favorable conditions for the development of convection,while the two rapids provided a steady stream of water vapor transport for the heavy rainfall.K exponential distribution,500 hPa,700 hPa temperature field and the total pseudo-equivalent potential temperature for the precipitation forecasts have a certain direction meaning.Japan fax map and MM5 grasped the precipitation forecasts better.展开更多
By using the data in 169 sounding stations over the world,NCEP/NCAR reanalysis data were tested,and the distribution characteristics of standard errors of geopotential height,temperature and wind speed field from the ...By using the data in 169 sounding stations over the world,NCEP/NCAR reanalysis data were tested,and the distribution characteristics of standard errors of geopotential height,temperature and wind speed field from the upper troposphere to the lower stratosphere over the world(most were the land zone) were analyzed.The results showed that the standard error distribution of reanalysis wind speed field data was mainly affected by the jet stream zone.There existed the obvious difference between the jet stream zone and the actual wind field.The distribution of standard error in the wind speed field had the obvious seasonal difference in winter,summer,and the average deviation was larger near the coastline.The high value zones of standard errors of reanalysis geopotential height and temperature field mainly concentrated in the low-latitude region in the Eastern Hemisphere(Indian Ocean coast).The distribution of standard error was basically consistent with average error.Therefore,the standard error could be explained well by the average error.The standard errors of reanalysis temperature and geopotential height data in the inland zone were lower.The high value zone mainly distributed along the coastline,and the average error of wind speed field was bigger near the coastline.It closely related to the quality of data in the sounding stations,the regional difference and the fact that the land observation stations were dense,and the ocean observation stations were fewer.展开更多
The synoptic-scale winter precipitation variations over southeastem China （22°-32°N, 105°-125°E） and their asso- ciation with the North Atlantic Oscillation （NAO） during 1951-2007 are investiga...The synoptic-scale winter precipitation variations over southeastem China （22°-32°N, 105°-125°E） and their asso- ciation with the North Atlantic Oscillation （NAO） during 1951-2007 are investigated in this paper. The variability of wintertime precipitation is characterized by meridional displacement of its maximum center. Two precipitation re- gimes, with maximum centers located over the Yangtze and Pearl River basins, are identified via cluster analysis. Time-lagged analyses suggest that the two precipitation regimes are connected with the decaying phases of positive NAO （NAO＋） events of different amplitudes. A strong （medium） NAO＋ event is defined as one when the maximum amplitude of the NAO index exceeds 1.0 （in the range of 0.7-1.0） for at least 4 consecutive days and drops to less than 0.3 within 7 days following the peak index. After the peak of a strong NAO＋, southerly winds expand north- ward to the Yangtze River （about 30°N）, a northeast-southwest-tilted trough migrates to east of Lake Baikal, and cold air intrudes into central eastern China; thus, precipitation is strengthened over the Yangtze River basin where warm and cold air masses converge. In comparison, during the decaying phase of medium NAO＋ events, the south- erly winds are relatively weak, and precipitation tends to be enhanced at lower latitudes （around 25°N）. Further ana- lysis indicates that downstream Rossby-wave propagation may account for the latitudinal expansion of the southerly wind anomalies over the eastern coastal area of China during the decaying phase of NAO＋ events of different strengths.展开更多
The rainfall in North China during rainy sea-son (July and August (JA)) exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation...The rainfall in North China during rainy sea-son (July and August (JA)) exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation of JA North China rainfall are examined. It is found that on the interannual timescale, the JA North China rainfall is associ-ated with significant SST anomalies in the equatorial eastern Pacific, and the North China rainfall and SST anomaly in the equatorial eastern Pacific correspond to the similar variation of the upper-level westerly jet stream over East Asia. A pos-sible mechanism is proposed for the influence of the SST anomalies in the equatorial eastern Pacific on the North China rainfall.展开更多
The relationships between the 200-hPa westerly jet stream anomalies over the East Asian coastal waterwestern Pacific （WPJS）, and the oceanic surface heating and synoptic-scale transient eddy （STE） activity anomali...The relationships between the 200-hPa westerly jet stream anomalies over the East Asian coastal waterwestern Pacific （WPJS）, and the oceanic surface heating and synoptic-scale transient eddy （STE） activity anomalies over the North Pacific in wintertime are examined by using ERA-40 and NCEP/NCAR reanalysis data. The analysis demonstrates that the surface heating and the STE anomalies have different patterns, corresponding to the three WPJS anomalous modes, respectively. In the first WPJS anomalous mode, the WPJS main part shows no robust anomaly. The anomalous westerly wind, occurring over the mid-latitude central-eastern Pacific past the date line is associated with the anomalous heating presenting both in the tropical central-eastern Pacific past the date line and the center of the North Pacific basin. Meanwhile, the STE anomaly appears around the region of the anomalous zonal wind. The fluctuation in jet strength shown in the second WPJS mode is strongly related to the heating anomaly in the Kuroshio Current region and the STE anomaly in the jet exit region. The third mode demonstrates a northward/southward shift of the WPJS, which has a statistical connection with a south-north dipolar pattern of the heating anomaly in the western North Pacific separated at 35°N. Meanwhile, the STE spatial displacement is in conjunction with jet shifts in the same direction. The heating anomaly has a close connection with the atmospheric circulation, and thus changes the mid-latitude baroclinicity, leading to the STE anomaly, which then reinforces the WPJS anomaly via internal atmospheric dynamics.展开更多
文摘根据1958-2011年中国东部（105°E以东）316站逐日降水资料及NCEP/NCAR逐日再分析资料,利用统计分析、物理量诊断等方法,探讨北方雨季（7月11日至8月31日）中国东部降水异常模态及同期、前期的大气环流特征。分析发现,北方雨季中国东部降水异常表现为三个相互独立的降水模态：第一模态为偏西型,当其时间系数为正（负）时,河套地区降水偏多（少）,江淮流域上游降水偏少（多）,南方大部降水偏多（少）;第二模态为北方一致型,当其时间系数为正（负）时,北方降水一致偏多（少）,长江流域降水偏少（多）;第三模态为偏东型,当其时间系数为正（负）时,东北南部至长江中游降水偏多（少）,华东沿海降水偏少（多）。研究发现,造成北方雨季三个降水异常模态的环流特征各不相同：偏西型降水主要受西亚高空副热带西风急流位置南北偏移影响;北方一致型降水主要由东亚—太平洋遥相关波列导致;偏东型降水主要与海陆气压异常对比造成的东亚夏季风变化有关。此外,三个模态与前期环流异常有密切联系。第一模态的正（负）异常由7月上旬200 h Pa来自北大西洋的异常波列造成乌拉尔山位势高度负（正）异常和巴尔喀什湖以南位势高度正（负）异常引起。第二模态的正（负）异常与前期7月上旬200 h Pa北大西洋上位势高度负（正）异常产生的沿中纬度（高纬度）路径向下游传播的波列有关。第三模态的正（负）异常由春季3月份低层蒙古上空异常的气旋（反气旋）持续至同期造成。
文摘The analysis of '09.08.19' regional rainstorm weather in Shenyang showed that the circulation situation of the rainfall was the typical subtropical high pressure with westerly trough.Surface cyclone development in cooperation with the convergence and the role of the front of the uplift produced by the heavy rains trigger mechanism.The coupling configuration of low-level jet created favorable conditions for the development of convection,while the two rapids provided a steady stream of water vapor transport for the heavy rainfall.K exponential distribution,500 hPa,700 hPa temperature field and the total pseudo-equivalent potential temperature for the precipitation forecasts have a certain direction meaning.Japan fax map and MM5 grasped the precipitation forecasts better.
基金Supported by The National Key Basic Research Development Plan(2010CB428602)
文摘By using the data in 169 sounding stations over the world,NCEP/NCAR reanalysis data were tested,and the distribution characteristics of standard errors of geopotential height,temperature and wind speed field from the upper troposphere to the lower stratosphere over the world(most were the land zone) were analyzed.The results showed that the standard error distribution of reanalysis wind speed field data was mainly affected by the jet stream zone.There existed the obvious difference between the jet stream zone and the actual wind field.The distribution of standard error in the wind speed field had the obvious seasonal difference in winter,summer,and the average deviation was larger near the coastline.The high value zones of standard errors of reanalysis geopotential height and temperature field mainly concentrated in the low-latitude region in the Eastern Hemisphere(Indian Ocean coast).The distribution of standard error was basically consistent with average error.Therefore,the standard error could be explained well by the average error.The standard errors of reanalysis temperature and geopotential height data in the inland zone were lower.The high value zone mainly distributed along the coastline,and the average error of wind speed field was bigger near the coastline.It closely related to the quality of data in the sounding stations,the regional difference and the fact that the land observation stations were dense,and the ocean observation stations were fewer.
基金Supported by the National Natural Science Foundation of China(41405047 and 41675086)China Meteorological Administration Special Public Welfare Research Fund(GYHY201306010)
文摘The synoptic-scale winter precipitation variations over southeastem China （22°-32°N, 105°-125°E） and their asso- ciation with the North Atlantic Oscillation （NAO） during 1951-2007 are investigated in this paper. The variability of wintertime precipitation is characterized by meridional displacement of its maximum center. Two precipitation re- gimes, with maximum centers located over the Yangtze and Pearl River basins, are identified via cluster analysis. Time-lagged analyses suggest that the two precipitation regimes are connected with the decaying phases of positive NAO （NAO＋） events of different amplitudes. A strong （medium） NAO＋ event is defined as one when the maximum amplitude of the NAO index exceeds 1.0 （in the range of 0.7-1.0） for at least 4 consecutive days and drops to less than 0.3 within 7 days following the peak index. After the peak of a strong NAO＋, southerly winds expand north- ward to the Yangtze River （about 30°N）, a northeast-southwest-tilted trough migrates to east of Lake Baikal, and cold air intrudes into central eastern China; thus, precipitation is strengthened over the Yangtze River basin where warm and cold air masses converge. In comparison, during the decaying phase of medium NAO＋ events, the south- erly winds are relatively weak, and precipitation tends to be enhanced at lower latitudes （around 25°N）. Further ana- lysis indicates that downstream Rossby-wave propagation may account for the latitudinal expansion of the southerly wind anomalies over the eastern coastal area of China during the decaying phase of NAO＋ events of different strengths.
基金supported by the Chinese Acad-emy of Sciences(Grant Nos.KZCX3-SW-221 and KZCX3-SW-218)the National Natural Science Foundation of China(Grant No.40221503).
文摘The rainfall in North China during rainy sea-son (July and August (JA)) exhibits a strong interannual variability. In this study, the atmospheric circulation and SST anomalies associated with the interannual variation of JA North China rainfall are examined. It is found that on the interannual timescale, the JA North China rainfall is associ-ated with significant SST anomalies in the equatorial eastern Pacific, and the North China rainfall and SST anomaly in the equatorial eastern Pacific correspond to the similar variation of the upper-level westerly jet stream over East Asia. A pos-sible mechanism is proposed for the influence of the SST anomalies in the equatorial eastern Pacific on the North China rainfall.
基金the National Natural Science Foundation of China under Grant Nos.40675041,40333026,and 40425009.
文摘The relationships between the 200-hPa westerly jet stream anomalies over the East Asian coastal waterwestern Pacific （WPJS）, and the oceanic surface heating and synoptic-scale transient eddy （STE） activity anomalies over the North Pacific in wintertime are examined by using ERA-40 and NCEP/NCAR reanalysis data. The analysis demonstrates that the surface heating and the STE anomalies have different patterns, corresponding to the three WPJS anomalous modes, respectively. In the first WPJS anomalous mode, the WPJS main part shows no robust anomaly. The anomalous westerly wind, occurring over the mid-latitude central-eastern Pacific past the date line is associated with the anomalous heating presenting both in the tropical central-eastern Pacific past the date line and the center of the North Pacific basin. Meanwhile, the STE anomaly appears around the region of the anomalous zonal wind. The fluctuation in jet strength shown in the second WPJS mode is strongly related to the heating anomaly in the Kuroshio Current region and the STE anomaly in the jet exit region. The third mode demonstrates a northward/southward shift of the WPJS, which has a statistical connection with a south-north dipolar pattern of the heating anomaly in the western North Pacific separated at 35°N. Meanwhile, the STE spatial displacement is in conjunction with jet shifts in the same direction. The heating anomaly has a close connection with the atmospheric circulation, and thus changes the mid-latitude baroclinicity, leading to the STE anomaly, which then reinforces the WPJS anomaly via internal atmospheric dynamics.
