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2007年,Ashok等揭示了赤道太平洋区域存在一种三极型分布海表温度异常并称之为厄尔尼诺-Modoki,同时定义了相应的海表温度异常指数EMI（记为IEM）。在此基础上,利用英国哈得来中心逐月海表温度资料、美国NCEP/NCAR月平均再分析数据集、美国国家海洋和大气管理局（NOAA）逐月降水资料（CMAP）,通过在太平洋海表温度异常中扣除厄尔尼诺-Modoki信号后,在Nino1+2区域上定义了东太平洋型海表温度异常指数EPNI（IEPN）。据此,由IEPN和IEM可构成描述热带太平洋海表温度异常变化的一对指数。分析了两个指数相应的海气状态及对海洋性大陆区域气候异常的影响。结果表明,厄尔尼诺-Modoki和东太平洋型海表温度异常及其影响存在显著差异。在北半球夏季,当IEM处于正位相时,热带太平洋海表温度异常呈现“负-正-负”的结构,海洋性大陆大部分区域海表温度异常为负,此时对流层低层太平洋地区辐合,海洋性大陆地区辐散,对流层高层太平洋地区辐散,海洋性大陆地区辐合。对应于辐合辐散中心,存在着自赤道中太平洋分别向赤道东太平洋和海洋性大陆中东部地区的异常垂直环流圈,同时也存在自海洋性大陆西部向印度洋西部的垂直环流。大气在海洋性大陆区域北部加热,南部冷却;在太平洋地区西部加热而东部冷却;在海洋性大陆区域10°N以南降水偏少,而10°N以北降水偏多。当IEPN处于正位相时,热带太平洋海表温度异常呈现“西负东正”分布型,海洋性大陆区域海表温度异常呈现“西正东负”分布,对流层低层海洋性大陆地区辐散中心范围偏大、位置偏东、强度偏强,太平洋地区辐合中心范围偏小、位置偏东,热带环流异常在垂直方向上呈斜压结构,海洋性大陆区域北部大气加热而南部冷却,太平洋地区大气均呈加热正异常,海洋性大陆大部分区域降水均偏少,赤道太平洋降水偏多。以上这些结果有利于深刻理解热带太平洋海表温度异常的特征及其对海洋性大陆区域气候的影响。 相似文献
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利用1979—2019年Hadley中心的海表温度资料、GPCP的降水资料以及NCEP-DOE的再分析资料等,分析了北半球春季热带南大西洋海表温度异常与北半球夏季亚澳季风区降水异常的联系。研究表明,北半球春季热带南大西洋海表温度异常与随后夏季热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区的降水异常为显著负相关（正相关）关系。北半球春季热带南大西洋的海表温度正异常可以引起热带大西洋和热带太平洋间的异常垂直环流,其中异常上升支（下沉支）位于热带大西洋（热带中太平洋）。热带中太平洋的异常下沉气流和低层辐散气流引起热带中西太平洋低层的异常东风,后者有利于热带中东太平洋海表温度出现负异常。通过Bjerknes正反馈机制,热带中东太平洋海表温度异常从北半球春季到夏季得到发展。热带中东太平洋海表温度负异常激发的Rossby波使得北半球夏季热带西太平洋低层出现一对异常反气旋。此时,850 hPa上热带西太平洋到海洋性大陆地区为显著的异常东风,有利于热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区出现异常的水汽辐散（辐合）,导致该地区降水减少（增加）。 相似文献
3.
2007年,Ashok等揭示了赤道太平洋区域存在一种三极型分布海表温度异常并称之为厄尔尼诺-Modoki,同时定义了相应的海表温度异常指数EMI（记为IEM）。在此基础上,利用英国哈得来中心逐月海表温度资料、美国NCEP/NCAR月平均再分析数据集、美国国家海洋和大气管理局（NOAA）逐月降水资料（CMAP）,通过在太平洋海表温度异常中扣除厄尔尼诺-Modoki信号后,在Nino1+2区域上定义了东太平洋型海表温度异常指数EPNI（IEPN）。据此,由IEPN和IEM可构成描述热带太平洋海表温度异常变化的一对指数。分析了两个指数相应的海气状态及对海洋性大陆区域气候异常的影响。结果表明,厄尔尼诺-Modoki和东太平洋型海表温度异常及其影响存在显著差异。在北半球夏季,当IEM处于正位相时,热带太平洋海表温度异常呈现“负-正-负”的结构,海洋性大陆大部分区域海表温度异常为负,此时对流层低层太平洋地区辐合,海洋性大陆地区辐散,对流层高层太平洋地区辐散,海洋性大陆地区辐合。对应于辐合辐散中心,存在着自赤道中太平洋分别向赤道东太平洋和海洋性大陆中东部地区的异常垂直环流圈,同时也存在自海洋性大陆西部向印度洋西部的垂直环流。大气在海洋性大陆区域北部加热,南部冷却;在太平洋地区西部加热而东部冷却;在海洋性大陆区域10°N以南降水偏少,而10°N以北降水偏多。当IEPN处于正位相时,热带太平洋海表温度异常呈现“西负东正”分布型,海洋性大陆区域海表温度异常呈现“西正东负”分布,对流层低层海洋性大陆地区辐散中心范围偏大、位置偏东、强度偏强,太平洋地区辐合中心范围偏小、位置偏东,热带环流异常在垂直方向上呈斜压结构,海洋性大陆区域北部大气加热而南部冷却,太平洋地区大气均呈加热正异常,海洋性大陆大部分区域降水均偏少,赤道太平洋降水偏多。以上这些结果有利于深刻理解热带太平洋海表温度异常的特征及其对海洋性大陆区域气候的影响。 相似文献
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1985年夏季长江和黄河流域降水异常成因的数值分析 总被引：7，自引：1，他引：7
1985年，赤道东太平洋地区海温全年为负距平，冷水范围宽广；赤道西太平洋大部分地区为海温正距平区，距平值在0.5℃左右。该年盛夏我国华南、华中和江淮流域相继出现干旱高温天气，江淮地区6月份的降水不及常年的一半。本文应用中国科学院大气物理研究所的两层大气环流模式（IAP-AGCM）,分别以观测得到的1985年赤道东太平洋和赤道西太平洋月平均海表温度场为外强迫源进行了两个区域海温异常的敏感性试验，分析了造成1985年夏季华南、华中和江淮流域干旱，而华北多雨的原因。另外，为了便于分析和比较，本文还以气侯平均的海 相似文献
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基于美国哥伦比亚大学Lamont-Doherty地球观象台LDEO(Lamont-Doherty Earth Observatory)海表温度资料和NCEP/NCAR再分析风场资料,分析了1997/1998年ElNio期间西太平洋暖池海表温度和西风距平的时间演变特征,同时也分析了东太平洋暖池海表温度和北风距平的时间演变特征。结果表明,1997/1998年ElNio事件期间,西太平洋暖池海表温度变化及异常西风和东太平洋暖池海表温度变化及异常北风都与Ni o3指数变化密切相关。将东、西太平洋暖池及异常北风、西风一并结合起来考虑,进一步研究了1997/1998年ElNio事件发生、发展的可能机制:异常西风驱动西太平洋暖池东端暖水向东伸展直接有利于赤道东太平洋海表温度增加;异常西风激发东传的暖Kelvin波对东太平洋的冷上升流有抑制作用,从而有利于赤道东太平洋海表温度增加;东传的异常西风可以通过埃克曼漂流效应将赤道两侧的海表暖水向赤道辐合从而加强了赤道附近的下沉流,也有利于赤道东太平洋赤道附近海表温度增加。几乎与此同时,北风距平通过产生北风吹流将东太平洋暖池暖水由北向南输送至赤道附近直接导致Nio3区海表温度增... 相似文献
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基于美国哥伦比亚大学Lamont—Doherty地球观象台LDEO（Lamont—DohertyEarth Observatory）海表温度资料和NCEP／NCAR再分析风场资料,分析了1997／1998年El Nino3期间西太平洋暖池海表温度和西风距平的时间演变特征,同时也分析了东太平洋暖池海表温度和北风距平的时间演变特征。结果表明,1997／1998年El Nino3事件期间,西太平洋暖池海表温度变化及异常西风和东太平洋暖池海表温度变化及异常北风都与Nino3指数变化密切相关。将东、西太平洋暖池及异常北风、西风一并结合起来考虑,进一步研究了1997／1998年El Nino3事件发生、发展的可能机制：异常西风驱动西太平洋暖池东端暖水向东伸展直接有利于赤道东太平洋海表温度增加;异常西风激发东传的暖Kelvin波对东太平洋的冷上升流有抑制作用,从而有利于赤道东太平洋海表温度增加;东传的异常西风可以通过埃克曼漂流效应将赤道两侧的海表暖水向赤道辐合从而加强了赤道附近的下沉流,也有利于赤道东太平洋赤道附近海表温度增加。几乎与此同时,北风距平通过产生北风吹流将东太平洋暖池暖水由北向南输送至赤道附近直接导致Nino3区海表温度增加。上述增温因素的叠加作用共同导致了1997／1998年El Nino事件迅速发生、异常强大。 相似文献
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本文利用一个全球大气环流说模式，对七月份赤道太平洋海温异常，北极海冰异常及高原积雪对西北太平洋副高和我国降水的影响进行数值试验，得出一些有铁结果。例如，当赤道东或西太平洋海表温度出现负距平时，副高较趋近负ＳＳＴＡ区，当出现正距平时，副高则远离正ＳＳＴＡ区；北区海冰覆盖面积较大时副高位置偏南，覆盖面积较小时副高位置偏北等等。 相似文献
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北太平洋海表温度与500hPa西太平洋副高和极涡相互作用的统计分析 总被引：2，自引：1，他引：2
本文采用斜交PROMAX因子分析方法分析了1954—1986年北太平洋逐月海表温度与500hPa西太平洋副高和极涡环流指数(7个因子)的相互关系,指出(1)500hPa西太平洋副高和极涡指数与北太平洋海温的相关值存在明显的年变化,以赤道太平洋区最敏感,(2)赤道东太平洋海表温度的变化与10个月前的极涡中心强度、同期和1—3个月前西太平洋副高面积、强度、位置变化有联系,(3)500hPa西太平洋副高面积和强度的变化受到前3—5个月赤道东太平洋和3个月前赤道中太平洋海表温度的影响,500hPa西太平洋副高位置与前3—5个月赤道东太平洋海表温度有联系. 相似文献
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Impact of Surface Sensible Heating over the Tibetan Plateau on the Western Pacific Subtropical High: A Land–Air–Sea Interaction Perspective 总被引：3，自引：0，他引：3
The impact of surface sensible heating over the Tibetan Plateau(SHTP) on the western Pacific subtropical high(WPSH)with and without air–sea interaction was investigated in this study. Data analysis indicated that SHTP acts as a relatively independent factor in modulating the WPSH anomaly compared with ENSO events. Stronger spring SHTP is usually followed by an enhanced and westward extension of the WPSH in summer, and vice versa. Numerical experiments using both an AGCM and a CGCM confirmed that SHTP influences the large-scale circulation anomaly over the Pacific, which features a barotropic anticyclonic response over the northwestern Pacific and a cyclonic response to the south. Owing to different background circulation in spring and summer, such a response facilitates a subdued WPSH in spring but an enhanced WPSH in summer. Moreover, the CGCM results showed that the equatorial low-level westerly at the south edge of the cyclonic anomaly brings about a warm SST anomaly(SSTA) in the equatorial central Pacific via surface warm advection.Subsequently, an atmospheric Rossby wave is stimulated to the northwest of the warm SSTA, which in turn enhances the atmospheric dipole anomalies over the western Pacific. Therefore, the air–sea feedbacks involved tend to reinforce the effect of SHTP on the WPSH anomaly, and the role of SHTP on general circulation needs to be considered in a land–air–sea interaction framework. 相似文献
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赤道东太平洋不同持续时间的海温正异常对东亚夏季气候影响的数值模拟研究 总被引：7，自引：1，他引：6
利用IAP两层大气环流模式及9层大气环流谱模式,模拟研究了大气对不同持续时间的赤道东太平洋正SSTA的响应。对积分结果进行分析发现,尽管SSTA的持续时间不同（分别为1月;1～2月及1～4月）,但其引起的东亚夏季大气环流和气候异常的分布却都十分相似,而且有十分相近的时间演变形式。因此,虽然赤道东太平洋SSTA作为一种外源强迫对东亚夏季大气环流和气候有着明显的影响,但是这种影响对于SSTA的持续时间（1个月或4个月）并不敏感,这在一定意义上意味着,如果利用模式进行短期气候预测,要更多的注意SSTA的发生（出 相似文献
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The interannual variations of rainfall over southwest China (SWC) during spring and
its relationship with sea surface temperature anomalies (SSTAs) in the Pacific are analyzed,
based on monthly mean precipitation data from 26 stations in SWC between 1961 and 2010,
NCEP/NCAR re-analysis data, and Hadley global SST data. Sensitivity tests are conducted to
assess the response of precipitation in SWC to SSTAs over two key oceanic domains, using the
global atmospheric circulation model ECHAM5. The interannual variation of rainfall over SWC in
spring is very significant. There are strong negative (positive) correlation coefficients
between the anomalous precipitation over SWC and SSTAs over the equatorial central Pacific
(the mid-latitude Pacific) during spring. Numerical simulations show that local rainfall in
the northwest of the equatorial central Pacific is suppressed, and a subtropical anticyclone
circulation anomaly is produced, while a cyclonic circulation anomaly in the mid-latitude
western Pacific occurs, when the equatorial Pacific SSTAs are in a cold phase in spring.
Anomalous northerly winds appear in the northeastern part of SWC in the lower troposphere.
Precipitation increases over the Maritime Continent of the western equatorial Pacific, while a
cyclonic circulation anomaly appears in the northwest of the western equatorial Pacific. A
trough over the Bay of Bengal enhances the southerly flow in the south of SWC. The trough also
enhances the transport of moisture to SWC. The warm moisture intersects with anomalous cold
air over the northeast of SWC, and so precipitation increases during spring. On the
interannual time scale, the impacts of the mid-latitude Pacific SSTAs on rainfall in SWC
during spring are not significant, because the mid-latitude Pacific SSTAs are affected by the
equatorial central Pacific SSTAs; that is, the mid-latitude Pacific SSTAs are a feedback to
the circulation anomaly caused by the equatorial central Pacific SSTAs. 相似文献
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利用1979-2015年NCEP/NCAR月平均再分析资料、美国国家海洋和大气管理局（NOAA）的月平均降水资料（CMAP）以及英国哈得来中心海表温度月平均资料,采用2009年Kao等定义的中部型ENSO指数,给出了夏季中部型海表温度（SST）异常指数,并分析了中部型ENSO和海洋性大陆（MC）区域气候的联系。结果表明,当夏季中部型海表温度正异常事件发生时,海洋性大陆核心区域（中太平洋）出现显著降水和气温负（正）异常,此时海洋性大陆核心区域有明显的负（正）热源异常,大气受冷却（加热）而下沉（上升）,同时潜热释放之外的非绝热加热表现为负（正）异常,易于导致降水负（正）异常。海洋性大陆区域与中太平洋间主要通过水平环流和垂直环流建立联系。（1）中部型ENSO指数显著正异常时,在对流层低（高）层,海洋性大陆区域和中太平洋间存在由关于赤道的对称气旋性（反气旋性）环流对而形成的直接联系,并使得海洋性大陆区域东部辐散（辐合）偏弱,而海洋性大陆区域西部辐散（辐合）偏强。（2）在垂直剖面上,赤道中太平洋海表温度的正异常和海洋性大陆核心区域的大气异常冷却有利于促使该地区低层赤道西风异常增强并进而利于中部型海表温度正异常的维持,并由此通过反沃克环流圈促进海洋性大陆区域下沉运动增强。此为海洋性大陆与中太平洋间的直接联系,可由皮叶克尼斯机制进行解释。而位于中太平洋与秘鲁地区的异常垂直环流亦可用这一机制进行解释。海洋性大陆与中太平洋的间接联系主要表现在由赤道外低纬和中纬度地区均存在的沿弧形路径上的垂直环流而建立的海洋性大陆与中太平洋地区的联系上。这些弧形垂直剖面上的垂直环流不仅与局地哈得来环流有关,还与热带和中纬度的罗斯贝波动有关。这些结果有利于深刻认识中部型ENSO对海洋性大陆区域气候的影响机理以及与热带外环流异常的联系。 相似文献
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Summer Persistence Barrier of Sea Surface Temperature Anomalies in the Central Western North Pacific
The persistence barrier of sea surface temperature anomalies(SSTAs) in the North Pacific was investigated and compared with the ENSO spring persistence barrier.The results show that SSTAs in the central western North Pacific(CWNP) have a persistence barrier in summer:the persistence of SSTAs in the CWNP shows a significant decline in summer regardless of the starting month.Mechanisms of the summer persistence barrier in the CWNP are different from those of the spring persistence barrier of SSTAs in the central and eastern equatorial Pacific.The phase locking of SSTAs to the annual cycle does not explain the CWNP summer persistence barrier.Remote ENSO forcing has little linear influence on the CWNP summer persistence barrier,compared with local upper-ocean process and atmospheric forcing in the North Pacific.Starting in wintertime,SSTAs extend down to the deep winter mixed layer then become sequestered beneath the shallow summer mixed layer,which is decoupled from the surface layer.Thus,wintertime SSTAs do not persist through the following summer.Starting in summertime,persistence of summer SSTAs until autumn can be explained by the atmospheric forcing through a positive SSTAs-cloud/radiation feedback mechanism because the shallow summertime mixed layer is decoupled from the temperature anomalies at depth,then the following autumn-winter-spring,SSTAs persist.Thus,summer SSTAs in the CWNP have a long persistence,showing a significant decline in the following summer.In this way,SSTAs in the CWNP show a persistence barrier in summer regardless of the starting month. 相似文献
16.
By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific inJanuary—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asiahas been studied.The results suggest that,due to the excitation of atmospheric low-frequencyoscillation by the SSTA,ENSO has significant lag influence on the monsoon over East Asia.During the summer after E1 Nino,the subtropical high over western Pacific is intensified andshows the northward and westward displacement,meanwhile,the rainfall over East China isbelow normal,especially in North China:during the winter after E1 Nino,both the Asian troughand the winter monsoon over East Asia are strengthened.During the summer after La Nina,theanomalous subtropical high prevails over the lower reaches of Yangtze(Changjiang)River,therainfall between Yangtze and Huaihe Rivers is below normal:during the winter after La Nina,both the Asian trough and the winter monsoon over East Asia are weaker.Compared with LaNina,the effect of El Nino is stronger,but it is not always opposite to the one of La Nina. 相似文献
17.
Recent advances in studies of the interaction between the East Asian winter and summer monsoons and ENSO cycle 总被引：26，自引：5，他引：21
Recent advances in studies on the interaction between the East Asian monsoon and the ENSO cycle are reviewed in this paper. Through the recent studies, not only have the responding features and processes of the East Asian winter and summer monsoon circulation anomalies and summer rainfall anomalies in East Asia to the ENSO cycle during its different stages been understood further, but also have the thermal and dynamic effects of the tropical western Pacific on the ENSO cycle been deeply analyzed from the observational facts and dynamic theories. The results of observational and theoretical studies showed that the dynamical effect of the atmospheric circulation and zonal wind anomalies in the lower troposphere over the tropical western Pacific on the ENSO cycle may be through the excitation of the equatorial oceanic Kelvin wave and Rossby waves in the equatorial Pacific. These studies demonstrated further that the ENSO cycle originates from the tropical western Pacific. Moreover, these recent studies also showed that the atmospheric circulation and zonal wind anomalies over the tropical western Pacific not only result from the air-sea interaction over the tropical western Pacific, but are also greatly influenced by the East Asian winter and summer monsoons. Additionally, the scientific problems in the interaction between the Asian monsoon and the ENSO cycle which should be studied further in the near future are also pointed out in this paper. 相似文献
18.
A premonitory sign of an anomalous SST over the eastern equatorial Pacific shows up in the North Pacific Subtropical Mode Water (STMW) 18 months earlier,and the air-sea relationship between the STMW and the anomalous SST over the eastern equatorial Pacific is shown.This premonitory connection involves an air-sea coupling between the longtime persistent mid-latitude sea surface temperature anomaly (SSTA) induced by the remote re-emergence of the STMW and the following spring subtropical atmospheric circulation anomalies.An examination of the air-sea interaction reveals that the following spring subtropical atmospheric circulation,which responds to the longtime persistent SSTA,is dominated by the anomalous negative (positive) geopotential height downstream of the negative (positive) SSTA in the strong (weak) STMW case.Thus,the tropics adjust to these anomalies through coupled dynamics,producing positive (negative) SST anomalies over the eastern equatorial Pacific.A cold water event that occurred over the eastern equatorial Pacific during winter 2008-09 was successfully forecasted by the weak summer STMW index in 2007.The evolution of this process for the air-sea interactions from the autumn of 2007 to December 2008 is presented. 相似文献
19.
Joint Impacts of SSTA in Tropical Pacific and Indian Oceans on Variations of the WPSH 总被引：2，自引：1，他引：1
Using the NCEP/NCAR reanalysis and HadISST sea surface temperature (SST) data, the joint effects of the tropical Indian Ocean and Pacific on variations of area of the summertime western Pacific subtropical high (WPSH) for period 1980–2016 are investigated. It is demonstrated that the central tropical Indian Ocean (CTI) and central equatorial Pacific (CEP) are two key oceanic regions that affect the summertime WPSH. During autumn and winter, warm SST anomalies (SSTAs) in CEP force the Walker circulation to change anomalously, resulting in divergence anomalies over the western Pacific and Maritime Continent (MC). Due to the Gill-type response, the abnormal anticyclonic circulation is generated over the western Pacific and South China Sea (SCS). In the subsequent spring, the warm SSTAs in CEP weaken, while the SST over CTI demonstrates a lagged response to Pacific SSTA. The warm CTISSTA and CEP-SSTA cooperate with the eastward propagation of cold Kelvin waves in the western Pacific, leading to the eastward shift of the abnormal divergence center that originally locates at the western Pacific and MC. The anticyclone forced by this divergence subsequently moves eastward, leading to the intensification of the negative vorticity there. Meanwhile, warm SSTA in CTI triggers eastward propagating Kelvin waves, which lead to easterly anomalies over the equatorial Indian Ocean and Indonesia, being favorable for maintenance and intensification of the anticyclone over the SCS and western Pacific. The monsoonal meridional–vertical circulation strengthens, which is favorable for the intensification of the WPSH. Using SSTA over the two key oceanic regions as predictors, a multiple regression model is successfully constructed for prediction of WPSH area. These results are useful for our better understanding the variation mechanisms of WPSH and better predicting summer climate in East Asia. 相似文献
20.
西太平洋副热带高压对热带
海温异常响应的研究 总被引：34，自引：5，他引：29
利用多年的观测资料,研究了西太平洋副热带高压对热带海温异常的响应及其相互作用过程。着重研究冬、夏季西太平洋副高对同期及前期不同海域（特别是赤道东、西太平洋以及印度洋海域）海温异常的响应;用SVD方法分析了夏季副热带高压与前冬、前春及同期各月全球海温的最佳耦合模态。在对比研究西太平洋副热带高压异常时其垂直环流变化的基础上,进而研究海气相互作用对副热带高压影响的物理过程。 相似文献