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81.
After compositing three representative ENSO indices,El Nio events have been divided into an eastern pattern(EP) and a central pattern(CP).By using EOF,correlation and composite analysis,the relationship and possible mechanisms between Indian Ocean Dipole(IOD) and two types of El Nio were investigated.IOD events,originating from Indo-Pacific scale air-sea interaction,are composed of two modes,which are associated with EP and CP El Ni o respectively.The IOD mode related to EP El Nio events(named as IOD1) is strongest at the depth of 50 to 150 m along the equatorial Indian Ocean.Besides,it shows a quasi-symmetric distribution,stronger in the south of the Equator.The IOD mode associated with CP El Nio(named as IOD2) has strongest signal in tropical southern Indian Ocean surface.In terms of mechanisms,before EP El Nio peaks,anomalous Walker circulation produces strong anomalous easterlies in equatorial Indian Ocean,resulting in upwelling in the east,decreasing sea temperature there;a couple of anomalous anticyclones(stronger in the south) form off the Equator where warm water accumulates,and thus the IOD1 occurs.When CP El Nio develops,anomalous Walker circulation is weaker and shifts its center to the west,therefore anomalous easterlies in equatorial Indian Ocean is less strong.Besides,the anticyclone south of Sumatra strengthens,and the southerlies east of it bring cold water from higher latitudes and northerlies west of it bring warm water from lower latitudes to the 15° to 25°S zone.Meanwhile,there exists strong divergence in the east and convergence in the west part of tropical southern Indian Ocean,making sea temperature fall and rise separately.Therefore,IOD2 lies farther south. 相似文献
82.
El Ni?o对东亚夏季风和夏季降水季节内变化的影响 总被引:3,自引:0,他引:3
基于1979~2012年候平均再分析资料,合成分析了El Ni?o对东亚夏季风和夏季降水季节内变化的影响。结果表明,在El Ni?o衰减年夏季,西太平洋副热带高压(副高)明显偏强,位置偏向西南。副高的这种异常特征随夏季的季节进程有明显变化,初夏异常较弱,盛夏期间异常达到最强。此外,根据东亚夏季风降水呈现阶段式北进的特征,将夏季分为华南前汛期、江淮梅雨期、华北和东北雨期以及华南后汛期来分析东亚夏季风和降水的季节内变化。在上述各个时期,大气对流层低层表现为一致的环流异常型,副高及其以南区域为异常反气旋,其北部为异常气旋。这种异常环流型加强了副高南部偏东风及其北部偏北风,增强了热带水汽输送和高纬度地区冷空气的入侵,二者结合造成主汛期地区降水增加。需要强调的是,上述环流异常型随东亚夏季风逐步向北推移,导致东亚各地区的主汛期降水增加,非主汛期降水减少,降水分布更为集中。 相似文献
83.
利用1979—2012年逐月Hadley中心海表温度、欧洲中期天气预报中心次表层海温、NCEP/NCAR风场再分析资料,对两类中太平洋(CP)El Nio及耦合的大气环流特征进行分析。结果表明,第一类CP El Nio(CP-ⅠEl Nio)增暖中心位于Nio4区且关于赤道对称;第二类CP El Nio(CP-ⅡEl Nio)的Nio4区与热带东北太平洋区域(NEP,130~110°W、15~25°N)同位相变化,冬季成熟后形成关于赤道非对称的带状增暖结构。进一步的研究表明,两类CP El Nio次表层结构存在差异:CP-ⅠEl Nio冬季次表层海温异常(SOTA)在中东太平洋与西太平洋呈显著偶极分布;CP-ⅡEl Nio在中、西太平洋位相相反但东太平洋异常较弱,且经向异常主要在赤道及其以北。两类CP El Nio耦合的大气环流特征不同:CP-ⅠEl Nio冬季异常Walker环流上升中心位于赤道上空,经向风向赤道辐合,低纬地区Hadley环流加强;CP-ⅡEl Nio冬季低层向北越赤道气流加强,Walker环流上升中心移到赤道以北,低纬地区Hadley环流减弱。 相似文献
84.
Cody Frick 《自然地理学》2016,37(1):26-37
There has been an enhanced focus on Atlantic tropical cyclone climatologies with the significant cyclones of the past decade and the associated loss of life and property. This study examines the geographic location of cyclone tracks and their relationship to El Niño-Southern Oscillation (ENSO). The average annual cyclone track latitude and longitude correlate positively with hurricane-season El Niño indices, indicating that during El Niño conditions, tropical cyclone tracks are shifted northward and eastward. June–November indices explain 11–22% and 3–11% of the variance in cyclone track latitude and longitude, respectively. Examination of the strongest and weakest El Niño years yields similar results. Higher sea level pressure over North America, a slight contraction of the Bermuda High, and a slight decrease in 500 mb heights during El Niño years helps to explain the observed northward and eastward movement of tropical cyclone tracks during El Niño years. Additionally, weaker easterly and stronger southerly winds on the western side of the North Atlantic Basin exist during El Niño years. Although future tropical cyclone track projection is beyond the scope of this research, these results may provide insight into forecast improvement and ultimately better responses for coastal communities. 相似文献
85.
1StrongtideandastronomicalconditionsPartial solar eclipse occurred 4 times in 1964, 1982 and 2000 respectively. Time interval is about 3 Saros periods (one Saros period is 18 years and 10.33~11.33 days). Total lunar eclipse occurred 2 times in 1964 and 2000 respectively and 3 times in 1982. However, there was no lunar eclipse in 1966, 1984 and 2002. It seems that they had similar astro-nomical conditions and the best was in 1982. The studies about the effect of tide on the global climate… 相似文献
86.
Cold water in the deep Pacific can be drawn up to the surface (or west warm water drifts eastwards ) because strong tide increases the mixing of seawater both in vertical and horizontal. In this way greenhouse effect is decreased or increased by means of absorbing (or releasing) CO2. Therefore, La Nina cold event (or El Nino warm event) may occur,which is caused by wanning - up or cooling - down air above the ocean. Volcanic action at sea bottom is also controlled by strong tide. 相似文献
87.
A two component mixed log-normal distribution effectively models annual precipitation totals at two stations in Peru characterized by widely differing interannual patterns of precipitation. Physical evidence supports the division of station records into two subsamples. Years with ENSO events and years without ENSO events identify the components of a mixed probability model. The mixed model produces a superior fit to the two parameter log-normal distribution. Model application provides a reliable means of precipitation prediction and also quantitatively describes the highly variable temporal and spatial pattern of annual precipitation in western Peru. 相似文献
88.
Cesar N. Caviedes 《The Professional geographer》1984,36(4):428-436
Recognized for years as a major environmental disruption, El Niño generated intense public interest in 1982–1983. During its last occurrence, this phenomenon, which develops in the tropical Pacific and usually affects rimlands of the Pacific basin, exceeded its boundaries and its effects were transmitted to continental North America, Europe, Africa and East Asia. Notwithstanding its vast areal extent, the interest of geographers in El Niño events, past and recent, has been comparatively less than that demonstrated by natural scientists and ecologists: little has been accomplished to place these climatic-ecological crises within global perspective. Lessons from El Niño include the acknowledgement of new concepts of climatic transitivity, ocean dynamics and energy exchanges that must find a place within the conceptual wealth of geography if this science intends to keep up with the rapid progress of other geosciences. 相似文献
89.
90.
厄尔尼诺事件和拉尼娜事件的成因与预测 总被引:5,自引:0,他引:5
通过对南极气温资料、环南极海冰资料、臭氧变化资料、太平洋海温资料、地球自转速度变化资料、厄尔尼诺和拉尼娜资料的综合验证,发现了构造运动与厄尔尼诺因果关系。大气、海洋与岩石圈的角动量交换在南半球和北半球有不同的形式,这是由陆海分布的差异决定的。南极上空臭氧变化和环南极海冰变化是赤道海温和全球气候准两年振荡的原因。其中,德雷克海峡的海冰变化起主要作用。这个结论给出了作者提出的“海洋锅炉效应”、“臭氧洞漏能效应”、“德雷克海冰气候开关效应”和“大洋地壳跷跷板运动”的相互关系,证明构造运动对厄尔尼诺的重要影响。强潮汐准4a周期的发现,表明南极海冰变化、东太平洋海温变化、地球自转变化和厄尔尼诺都具有4a准周期变化的原因。海温和海冰开关的准2a周期和日食-厄尔尼诺系数理论有较好的预测效果。 相似文献