热带太平洋次表层海温异常年代际变率及其对中国气候异常的影响

利用近50年月平均的SODA海洋同化资料和NCEP大气再分析资料,研究了热带太平洋次表层海温异常(SOTA)年代际变率主要分布型以及与之相关的亚洲-北太平洋-北美地区上空异常大气环流场,并揭示了类ENSO模态与中国气候异常之间的联系.得到主要结果:(1)热带太平洋SOTA年代际变率有两种类ENSO模态.第一模为类ENSO事件成熟期热带太平洋年代际SOTA状态；第二模为类ENSO过渡期热带太平洋年代际SOTA状态.二者组合构成类ENSO事件40年左右及其背景下13年左右的周期振荡.(2)类ENSO事件对亚洲-北太平洋-北美上空中高纬和副热带大气系统年代际变化具有重要影响.类El Ni(n)o成熟期间冬季,中高纬地区大气环流经向型发展,贝加尔湖高压脊加强,西太平洋副高偏强、位置偏西,蒙古高原为较强的异常反气旋环流.类El Ni(n)o衰退期(类La Ni(n)a发展期)夏季,贝加尔湖低压槽加深,乌拉尔山高压脊加强,西太平洋副高偏弱,新疆-河套地区为较强的异常反气旋环流距平.类La Ni(n)a事件时相反.(3)热带太平洋类ENSO事件通过影响中高纬和副热带大气系统,造成中国北部地区上空南风距平的年代际变化,进而导致东亚季风和中国气候异常.类El Ni(n)o事件成熟期,中国北部地区上空多异常偏北风,东亚季风弱,华北少雨,长江中、下游多雨；类El Ni(n)o衰退(类La Ni(n)a发展)期,中国北部地区上空亦为异常偏北气流,东亚季风较弱,华北少雨.中国气候异常型主要取决于类ENSO第一模态,而第二模态主要视位相异同来加强或减弱第一模态.两个类ENSO模态的共同作用导致1978年前后中国气候跃变和华北地区持续20余年的干旱.近期类ENSO模的振荡从1998年左右开始转为类La Ni(n)a模态,大致在2018年左右结束.在此期间,华北降水有望增加,长江中、下游降水可能减少.     

ENSO cycle and climate anomaly in China

The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly (SOTA) and the associated anomalous atmospheric circulation over the Asian North Pacific during the El Ni o-Southern Oscillation (ENSO) were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/NCAR) atmospheric reanalysis data and simple ocean data simulation (SODA). The relationship between the ENSO and the climate of China was revealed. The main results indicated the following: 1) there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2) during the mature phase of El Ni o, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of El Ni o, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Ni a event causes an opposite, but weaker effect; 3) the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the "atmospheric-bridge", where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper.     

数字地球的体系研究

通过对地学空间信息研究背景及其内容的分析,认为数字地球是人类空间信息革命的序幕。并结合数字地球的关键技术,提出了数字地球的全球层、区域层以及国家层的实现模式。文章还对数字地球的应用领域展开了讨论,认为数字地球是人类下个世纪经济增长的关键,并是人类适居社区等建设的决策信息支柱。     

DECADAL VARIABILITY OF SUBSURFACE OCEAN TEMPERATURE ANOMALY IN TROPICAL PACIFIC AND ITS IMPACT ON CLIMATE OF CHINA

In this study,we investigate the decadal variability of subsurface ocean temperature anomaly(SOTA)in the tropical Pacific and associated anomalous atmospheric circulation over Asia-North Pacific-North America by analyzing 50 years of atmosphere-ocean data from the National Center for Environmental Prediction(NCEP)reanalysis project and Simple Ocean Data Assimilation(SODA).Relationship between the ENSO-Like variability and climate of China is also revealed.The results show that the decadal variability of tropical Pacific SOTA has two dominant ENSO-like modes:the primary mode is an ENSO-Like mature phase pattern,and the second mode is associated with the ENSO-like transition(developing or decaying)phase.These two modes consist of a cycle of ENSO-Like variability,which exhibits a quasi-40a fluctuation,superimposed with an oscillation of a 13a period.The ENSO-Like variability in the tropical Pacific influences the atmosphere system at the mid-and higher-latitudes and subtropical regions,resulting in decadal variability of south wind over North China,the East Asian monsoon and climate of China.During the mature phase of El Ni o-Like variability,the anomalous north wind prevails over the north part of China and the East Asian monsoon weakens,with little rain in North China but much rain in the middle-and lower-reaches of the Yangtze River.With El Ni o-Like decaying(La Ni a-Like developing),anomalous northerly wind also prevails over North China,then the East Asian monsoon weakens with drought occurring in North China.The situation during the La Ni a-Like variability is the opposite.The pattern of anomalous climate of China is primarily dominated by the first ENSO-like variability,while the second mode can modulate the contribution of the first one,depending on whether its phase agrees with that of the first mode.The climate shift in China around 1978 and successive occurrence of drought for more than 20 years in North China are primarily induced by the first two ENSO-like variabilities.The latest La Ni a-Like phase starts from 1998 and will presumably end around 2018.It is expected that more rainfall would be in North China and less rainfall would appear in the middle-and lower-reaches of the Yangtze River valley during this period.     

热带太平洋第二类El Nio事件及其对中国气候的影响

基于热带太平洋次表层海温资料,分析了热带太平洋第二类El Nio事件海温异常的分布特征及其形成机制,讨论了与经典El Nio事件、El Nio Modoki、WP(西太平洋暖池)及CT(冷舌)El Nio事件之间的关系,揭示了第二类El Nio事件对中国降水的影响,得到以下结论。(1)第二类El Nio事件表征为热带太平洋次表层海温异常第三模态,占总方差贡献的4.7%。在海洋表面层,第二类El Nio事件暖期赤道东太平洋为沿赤道西伸的冷舌,热带中西太平洋为环绕冷舌的马蹄型大范围暖区。该型具11a和30~40a年代际振荡及3~4a年际变率,峰值多出现在春季。第二类El Nio事件是热带太平洋异常海面风应力场和赤道两侧的风应力旋度共同作用的结果,在赤道东印度洋-中西太平洋与赤道东太平洋-南美洲上空出现以反号垂直运动为特征的异常Walker环流。(2)El Nio Modoki与第二类El Nio事件有密切关系,它实质上是第二类El Nio事件次表层海温与近海面大气相互作用的结果,捕捉了第二类El Nio事件的主要信息。(3)第二类El Nio事件对中国春季及夏初降水有一定影响。在事件暖期,东海地区存在一个显著的异常反气旋性环流,其南侧的中国南方地区盛行异常东北气流,水汽来源减少,导致该地区少雨,其西侧的异常偏南气流北上直达华北地区,异常多水汽向北输送,并与北方的偏北流场相遇,导致该地区降水偏多。在第二类El Nio事件冷期相反。本文结果还指出,WP与CT El Nio事件是由经典El Nio事件第一模态与El Nio Modoki事件组合而成,它们不是独立的El Nio类型。此外,还讨论了夏半年El Nio事件对大气环流影响的物理过程。     

ENSO相联系的热带太平洋上层海洋异常环流

本文使用SODA(simple ocean data assimilation)海洋同化资料,系统分析了厄尔尼诺-南方涛动(El Ni?o-Southern Oscillation,ENSO)循环中冷暖位相期间热带太平洋上层海洋环流的演变规律,探讨了形成海洋环流异常的新机制。结果表明,在厄尔尼诺成熟期,热带中东太平洋赤道潜流最弱,赤道两侧出现反气旋性环流异常;西太平洋赤道外热带海域出现气旋性环流异常,该区南、北赤道流、棉兰老流、黑潮、新几内亚沿岸潜流及南赤道逆流增强;北赤道逆流区出现异常气旋性环流串,北赤道逆流接近正常。在厄尔尼诺衰退期和拉尼娜发展期,热带中西太平洋赤道潜流达到极强,赤道两侧出现气旋性环流异常;西太平洋赤道外热带海域异常环流减弱,该处主要流场的强度减弱或处于正常状态;北赤道逆流区反转为异常西向流。结果表明, ENSO循环期间的上层海洋环流异常受到热带太平洋温跃层深度异常产生的压强梯度力异常调控,在赤道外热带海洋温跃层深度异常和科里奥利力共同作用产生大尺度海洋环流异常,而在赤道海域,海洋温跃层深度异常和Gill效应造成赤道潜流异常以及关于赤道对称的气旋或反气旋性环流异常。     

数字专题图形快速编辑方法探讨

以扫描形成的数字矢量底图为基础，对建立沙漠化专题图形库系统中耗资最大的图形编辑问题进行了系列研究，并在以图形工作站和微机组成的分布式网络系统中，形成了可用于建立沙漠化专题图形库的图形快速编辑系统     

THE CLIMATIC JUMP OF THE WESTERN PACIFIC WARM POOL AND ITS CLIMATIC EFFECTS

1INTRODUCTIONTropicalwesternPacificOceanisanareathathasthehighestoceantemperatureacrosstheglobe.Asmostofthewarmwaterconcentratesintheregion,itisknownasthe搘esternPacificwarmpool?Asshowninsomestudies[1-5],thegeneralcirculationandshort-termclimaticchangeswillbeseriouslyaffectedifthermodynamicconditionchangesinthewaters,whichthenhaveanimportantroletoplayintheonsetofanyENSOepisodes.Therehasnotbeenanyunifieddefinitionoftheindexforthewarmpool.FollowingthecriterionofWyrtki[4],however,theareae…     

中纬度海气相互作用研究进展

回顾了中纬度海气相互作用的研究现状,分析了长期以来该项研究进展缓慢的原因和近十几年来的研究成果,结果指出:中纬度海洋在全球气候变化中有着重要的作用;冬季中纬度海气相互作用的强信号是冷空气强度;中纬度海洋强暖流区海气能量交换异常对同期和后期(半年至一年)北半球范围内的大气环流型有重要影响;当冬季黑潮和湾流海域海洋对大气同时异常多或异常少加热时,易形成夏季长江中下游偏旱或偏涝的环流形势。最后还提出,深入研究中纬度海气能量系统异常对大气环流影响及其物理机制,是今后海气相互作用研究的重要内容,其结果将为短期气候预测提供理论依据。     

专题图形库信息定量研究方法

本文以作者建立和科尔沁典型沙区专题图形库为例，对利用库信息进行沙漠化定量研究的图形方法进行了系列探讨，设计了可用于沙漠化定量研究的专题分析软件，并对该区的沙漠化现状进行了示例性研究。