Results of the definition of South China Sea summer monsoon onset date and East Asian summermonsoon index in recent years are summarized in this paper. And more questions to be resolved are introducedlater.
An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric R...An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric Research (NCEP/NCAR). It is found that the difference between the geopotential thickness over Guangzhou and Manila can be used as an alternative index for the onset of summer monsoon over the SCS. Since the convective heating alters the geopotential height and the distance between Guangzhou and Manila is of synoptic scale in the geostraphic framework, the index can represent the strength of heating and the first baroclinic cell over the SCS. By comparison between different indices, it is found that the summer monsoon onset over the SCS can be ascertained by the vertical zonal wind shear between 200 hPa and 850 hPa, the zonal wind at 850 hPa, the OLR anomaly, and the alternative index defined in the present paper. The meridional wind shear between 200 hPa and 850 hPa always appears over the SCS much earlier than the zonal wind shear and cannot be used as an index under consideration.展开更多
We analyze statistically different definitions of the South China Sea summer monsoon(SCSSM) onset are to establish a SCSSM onset time series that is more recognizable by a majority of indicators.With the acknowledged ...We analyze statistically different definitions of the South China Sea summer monsoon(SCSSM) onset are to establish a SCSSM onset time series that is more recognizable by a majority of indicators.With the acknowledged index,we determine a key area(105°E-112.5°E,7.5°N-12.5°N) and define the zonal wind component in this key area as a new SCSSM onset index,using daily mean reanalysis data of the National Center for Environmental Prediction/National Center for Atmospheric Research.The atmospheric circulations before and after the onset of the SCSSM determined using the index defined in this paper are preliminarily studied.Results show that the Somalia cross-equatorial flow is enhanced,the strongest westerly wind in the tropical Indian Ocean shifts northward,the cyclone couple in the Bay of Bengal and the Southern Hemisphere weaken and move eastward,convection over the South China Sea increases,and the subtropical high retreats from the South China Sea after the outbreak of the SCSSM.By analyzing the atmospheric circulation,it is found that in 1984 and 1999,the SCSSM broke out in pentads 29 and 23,respectively,which is consistent with the onset times determined using our index.展开更多
According to the basic characteristics of the activities of summer monsoon in the South China Sea, a standardized index, sI, has been designed that integrates a dynamic factor (southwesterly component) and a thermodyn...According to the basic characteristics of the activities of summer monsoon in the South China Sea, a standardized index, sI, has been designed that integrates a dynamic factor (southwesterly component) and a thermodynamic factor (OLR) for the indication of summer monsoon in the South China Sea. With the index determined for individual months of June, July and August and the entire summertime from 1975 to 1999, specific months and years are indicated that are either strong or weak in monsoon intensity. The variation is studied for the patterns and sI抯 relationship is revealed with the onset of summer monsoon and the precipitation in Guangdong province and China. The results show that there are quasi-10 and quasi-3-4 year cycles in the interannual variation of the monsoon over the past 25 years. When it has an early (late) onset, the summer monsoon is usually strong (weak). In the strong (weak) monsoon years, precipitation tends to be more (less) in the first raining season of the year but normal or less (normal) in the second, in the province, but it would be more (less) in northeastern China and most parts of the northern China and south of the lower reaches of the Changjiang River and less (more) in the middle and lower reaches of the river, western part of northern China and western China.展开更多
The short-range climate predictions of the onset and intensity of the South China Sea summer monsoon (SCSSM) are studied by statistical and synthesis methods.The relationship between the South China Sea monsoon index ...The short-range climate predictions of the onset and intensity of the South China Sea summer monsoon (SCSSM) are studied by statistical and synthesis methods.The relationship between the South China Sea monsoon index (SCSMI) and the environmental fields,such as 850 hPa winds, 500 hPa heights,SSTs,OLR,is examined.The possible mechanism of the relationship with SCSSM is discussed.The anomaly of the winter SCSMI and the preceding environmental fields may be used as a precursor signal to predict the onset and intensity of SCSSM.Based on the above research results,a conceptual model was constructed to predict the onset and intensity of SCSSM. The results for the trial prediction during 1998 to 2001 have presented satisfactory results.展开更多
运用澳大利亚大气海洋耦合预报模式(Predictive Ocean Atmosphere Model for Australia,POAMA)的输出结果,采用泰勒图与分类统计分析方法,评估了该模式对2003和2004年南海夏季风的爆发和演变进行实时预报的能力。通过对泰勒图的分析发现...运用澳大利亚大气海洋耦合预报模式(Predictive Ocean Atmosphere Model for Australia,POAMA)的输出结果,采用泰勒图与分类统计分析方法,评估了该模式对2003和2004年南海夏季风的爆发和演变进行实时预报的能力。通过对泰勒图的分析发现,随着预报初始时间越来越接近实际的季风爆发时间,模式预报南海夏季风爆发和演变的能力越来越强。当提前1—30d预报南海夏季风时,模式能够很好地预报风场、射出长波辐射OLR(Outgoing Longwave Radiation)和降水场的空间分布,其中对风场的预报最好。通过对季风爆发指数和分类统计的分析,定量分析了模式预报南海夏季风爆发的能力,结果表明该模式对南海夏季风爆发时间有一定的预报能力,其最大预报时限可以提前10—15d左右,这与目前中期预报的上限(2周)是一致的。展开更多
利用代表南海夏季风季节内振荡特征的850 hPa纬向风EOF分解的前两个主成分,定义南海夏季风季节内振荡指数,并利用美国国家环境预测中心第2代气候预报系统(NCEP Climate Forecast System Version 2,NCEP/CFSv2)提供的1982 2009年逐日回...利用代表南海夏季风季节内振荡特征的850 hPa纬向风EOF分解的前两个主成分,定义南海夏季风季节内振荡指数,并利用美国国家环境预测中心第2代气候预报系统(NCEP Climate Forecast System Version 2,NCEP/CFSv2)提供的1982 2009年逐日回算预报场计算了南海夏季风季节内振荡指数的预报值,用于我国南方地区持续性强降水的预报试验。试验结果表明:利用南海夏季风季节内振荡实时监测指数与模式直接预报降水量相结合的统计动力延伸预报方法,能够有效提高季节内降水分量的预报效果。同时,该方法能够避免末端数据损失,修正了对模式预报降水直接进行带通滤波而导致的负相关现象,并起到消除模式系统误差的作用。展开更多
基金Natural Science Foundation of China (grant No.40233027)Natural Science Foundation ofChina (Project 90211010)"Research on the monitoring and service of South China Sea monsoons", ResearchFund for Tropical Marine Meteorology
文摘Results of the definition of South China Sea summer monsoon onset date and East Asian summermonsoon index in recent years are summarized in this paper. And more questions to be resolved are introducedlater.
基金the support for this work from China Ministry of Education
文摘An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric Research (NCEP/NCAR). It is found that the difference between the geopotential thickness over Guangzhou and Manila can be used as an alternative index for the onset of summer monsoon over the SCS. Since the convective heating alters the geopotential height and the distance between Guangzhou and Manila is of synoptic scale in the geostraphic framework, the index can represent the strength of heating and the first baroclinic cell over the SCS. By comparison between different indices, it is found that the summer monsoon onset over the SCS can be ascertained by the vertical zonal wind shear between 200 hPa and 850 hPa, the zonal wind at 850 hPa, the OLR anomaly, and the alternative index defined in the present paper. The meridional wind shear between 200 hPa and 850 hPa always appears over the SCS much earlier than the zonal wind shear and cannot be used as an index under consideration.
基金Supported by the National Natural Science Foundation of China (Nos. 40876004,40890150/D0601)the National Basic Research Program of China (973 Program) (Nos. 2007CB411801,2005CB422301)
文摘We analyze statistically different definitions of the South China Sea summer monsoon(SCSSM) onset are to establish a SCSSM onset time series that is more recognizable by a majority of indicators.With the acknowledged index,we determine a key area(105°E-112.5°E,7.5°N-12.5°N) and define the zonal wind component in this key area as a new SCSSM onset index,using daily mean reanalysis data of the National Center for Environmental Prediction/National Center for Atmospheric Research.The atmospheric circulations before and after the onset of the SCSSM determined using the index defined in this paper are preliminarily studied.Results show that the Somalia cross-equatorial flow is enhanced,the strongest westerly wind in the tropical Indian Ocean shifts northward,the cyclone couple in the Bay of Bengal and the Southern Hemisphere weaken and move eastward,convection over the South China Sea increases,and the subtropical high retreats from the South China Sea after the outbreak of the SCSSM.By analyzing the atmospheric circulation,it is found that in 1984 and 1999,the SCSSM broke out in pentads 29 and 23,respectively,which is consistent with the onset times determined using our index.
基金 Research on the Formation Mechanism and Prediction Theory of Severe Climate Disasters in China (G1998040900(I))
文摘According to the basic characteristics of the activities of summer monsoon in the South China Sea, a standardized index, sI, has been designed that integrates a dynamic factor (southwesterly component) and a thermodynamic factor (OLR) for the indication of summer monsoon in the South China Sea. With the index determined for individual months of June, July and August and the entire summertime from 1975 to 1999, specific months and years are indicated that are either strong or weak in monsoon intensity. The variation is studied for the patterns and sI抯 relationship is revealed with the onset of summer monsoon and the precipitation in Guangdong province and China. The results show that there are quasi-10 and quasi-3-4 year cycles in the interannual variation of the monsoon over the past 25 years. When it has an early (late) onset, the summer monsoon is usually strong (weak). In the strong (weak) monsoon years, precipitation tends to be more (less) in the first raining season of the year but normal or less (normal) in the second, in the province, but it would be more (less) in northeastern China and most parts of the northern China and south of the lower reaches of the Changjiang River and less (more) in the middle and lower reaches of the river, western part of northern China and western China.
基金Project supported by the SCSMEX of the Climbing Programme"A"under the Ministry of Science and Technology
文摘The short-range climate predictions of the onset and intensity of the South China Sea summer monsoon (SCSSM) are studied by statistical and synthesis methods.The relationship between the South China Sea monsoon index (SCSMI) and the environmental fields,such as 850 hPa winds, 500 hPa heights,SSTs,OLR,is examined.The possible mechanism of the relationship with SCSSM is discussed.The anomaly of the winter SCSMI and the preceding environmental fields may be used as a precursor signal to predict the onset and intensity of SCSSM.Based on the above research results,a conceptual model was constructed to predict the onset and intensity of SCSSM. The results for the trial prediction during 1998 to 2001 have presented satisfactory results.
文摘运用澳大利亚大气海洋耦合预报模式(Predictive Ocean Atmosphere Model for Australia,POAMA)的输出结果,采用泰勒图与分类统计分析方法,评估了该模式对2003和2004年南海夏季风的爆发和演变进行实时预报的能力。通过对泰勒图的分析发现,随着预报初始时间越来越接近实际的季风爆发时间,模式预报南海夏季风爆发和演变的能力越来越强。当提前1—30d预报南海夏季风时,模式能够很好地预报风场、射出长波辐射OLR(Outgoing Longwave Radiation)和降水场的空间分布,其中对风场的预报最好。通过对季风爆发指数和分类统计的分析,定量分析了模式预报南海夏季风爆发的能力,结果表明该模式对南海夏季风爆发时间有一定的预报能力,其最大预报时限可以提前10—15d左右,这与目前中期预报的上限(2周)是一致的。
文摘利用代表南海夏季风季节内振荡特征的850 hPa纬向风EOF分解的前两个主成分,定义南海夏季风季节内振荡指数,并利用美国国家环境预测中心第2代气候预报系统(NCEP Climate Forecast System Version 2,NCEP/CFSv2)提供的1982 2009年逐日回算预报场计算了南海夏季风季节内振荡指数的预报值,用于我国南方地区持续性强降水的预报试验。试验结果表明:利用南海夏季风季节内振荡实时监测指数与模式直接预报降水量相结合的统计动力延伸预报方法,能够有效提高季节内降水分量的预报效果。同时,该方法能够避免末端数据损失,修正了对模式预报降水直接进行带通滤波而导致的负相关现象,并起到消除模式系统误差的作用。
