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赤道印度洋—太平洋地区海气系统的齿轮式耦合和ENSO事件 I.资料分析 总被引：26，自引：16，他引：10
利用历史观测数据，研究了印度洋海表温度（ＳＳＴ）的季节变化特征，证实赤道印度洋和东太平洋ＳＳＴ年际变化有显著的正相关，指出这种正相关是由于沿赤道印度洋上空纬向季风环流和太平洋上空Ｗａｌｋｅｒ环流之间显著的耦合造成的。这两个异常的纬向环流圈之间的耦合形式看起来很象是存在于赤道印度洋和太平洋上空的一对齿轮（简写为ＧＩＰ），当一个作顺时向变化时，另一个则作反时向变化。文中还证明ＥＮＳＯ事件与ＧＩＰ的年际异常存在很好的对应关系，暖事件时ＧＩＰ为反向运转；冷事件时ＧＩＰ为正向运转；异常的ＧＩＰ的啮合点位于印尼群岛附近。对８０年代以来的ＥＮＳＯ事件的分析表明，每次事件前期异常的ＧＩＰ的啮合点首先出现在印度洋上空，然后逐渐传入太平洋，引起ＧＩＰ东侧的大气纬向风ｕ和ＳＳＴ同时发生异常变化。当这种风场和ＳＳＴ的异常变化发展东传到达赤道中东太平洋时，导致ＥＮＳＯ事件最终出现。本文由此指出印度洋上空纬向环流的异常可以通过印度洋和太平洋上空大气系统的齿轮式耦合去影响赤道中东太平洋的海－气相互作用并触发ＥＮＳＯ事件发生。 相似文献
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该文用850 hPa和200 hPa纬向风距平差定义南海热带季风、沃克环流及热带环流强度指数，并讨论它们的天气气候学意义。指出由南海热带季风指数和沃克环流指数之差表征的热带环流强度指数与我国夏季降水，尤其是与长江流域降水有密切的关系；通过热带环流强度指数与冬、春、夏季500 hPa高度场、SLP、SST、OLR的相关分析，揭示用热带环流强度指数表征的热带环流异常影响我国夏季降水的可能途径。热带环流强度指数的季节变化规律及其与前期环境场的相关关系，对夏季雨带位置的预报有一定的参考价值。 相似文献
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Impact of the Thermal State of the Tropical Western Pacific on Onset Date and Process of the South China Sea Summer Monsoon 总被引：8，自引：0，他引：8 
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下载免费PDF全文 Since the early or late onset of the South China Sea summer monsoon （SCSM） has a large impact on summer monsoon rainfall in East Asia, the mechanism and process of early or late onset of the SCSM are an worthy issue to study. In this paper, the results analyzed by using the observed data show that the onset date and process of the SCSM are closely associated with the thermal state of the tropical western Pacific in spring. When the tropical western Pacific is in a warming state in spring, the western Pacific subtropical high shifts eastward, and twin cyclones are early caused over the Bay of Bengal and Sumatra before the SCSM onset. In this case, the cyclonic circulation located over the Bay of Bengal can be early intensified and become into a strong trough. Thus, the westerly flow and convective activity can be intensified over Sumatra, the Indo-China Peninsula and the South China Sea （SCS） in mid-May. This leads to early onset of the SCSM. In contrast, when the tropical western Pacific is in a cooling state, the western Pacific subtropical high anomalously shifts westward, the twin cyclones located over the equatorial eastern Indian Ocean and Sumatra are weakened, and the twin anomaly anticyclones appear over these regions from late April to mid-May. Thus, the westerly flow and convective activity cannot be early intensified over the Indo-China Peninsula and the SCS. Only when the western Pacific subtropical high moves eastward, the weak trough located over the Bay of Bengal can be intensified and become into a strong trough, the strong southwesterly wind and convective activity can be intensified over the Indo-China Peninsula and the SCS in late May. Thus, this leads to late onset of the SCSM. Moreover, in this paper, the influencing mechanism of the thermal state of the tropical western Pacific on the SCSM onset is discussed further from the Walker circulation anomalies in the different thermal states of the tropical western Pacific. 相似文献
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Interactions between the 30–60 day oscillation,the walker circulation and the convective activities in the tropical western pacific and their relations to the interannual oscillation 总被引：5，自引：0，他引：5 下载免费PDF全文
下载免费PDF全文 Huang Ronghui 《大气科学进展》1994,11(3):367-384
In this paper, interactions between the 30-60 day oscillation, the Walker circulation and the convective activities in the tropical western Pacific during the Northern Hemisphere summer are analyzed by using the observed data of wind fields and high-cloud amounts for the period from 1980 to 1989.The analyzed results show that the 30-60 day oscillation (hereafter called LFO) may be largely affected by the convective activities in the tropical western Pacific. The LFO in the tropical western Pacific during the strong convective activities around the Philippines stronger than those during the weak convective activities around the Philippines. Moreover, in the case of strong convective activities around the Philippines, the LFO in the tropical west-ern Pacific and tropical eastern Indian Ocean generally propagates westward, and it is intensified by the LFO with a westward propagating center of maximum oscillation from the east to 140oE. However, in the case of weak convective activities around the Philippines, the LFO gradually becomes stronger with a eastward propagating center of maximum oscillation from the eastern Indian Ocean to the tropical western Pacific.Corresponding to the 30-60 day oscillation, the Walker circulation is also in oscillation over the tropical Pacific and its circulation cell seems to shift gradually westward from the tropical western Pacific to the tropical eastern In-dian Ocean with strong convective activities around the Philippines. This may maintain the intensification of convective activities there. However, during the weak convective activities around the Philippines, the Walker circula-tion gradually moves eastward and an ascending flow may appear in the equatorial central Pacific. This may cause convective activities to be intensified over the equatorial central Pacific.The analyzed results also show that the LFO in the tropical western Pacific and East Asia may be associated with the interannual oscillation of the SST anomaly in the tropical western Pacific. 相似文献
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Variability of global lightning activity on the ENSO time scale 总被引：2，自引：0，他引：2
Global lightning activity has been studied on the ENSO (El Niño Southern Oscillation) time scale based on recordings of the Earth's Schumann resonances at Nagycenk (NCK), Hungary as well as observations from the OTD (Optical Transient Detector) and the LIS (Lightning Imaging Sensor) satellites in space. Both the intensity and position of lightning activity vary on the ENSO time scale. The magnitude of the global variation in lightning flash rate is ~10% from La Niña to El Niño. In general, more lightning is observed in the tropical–extratropical land regions during warm, El Niño episodes, especially in Southeast Asia. Although oceanic lightning activity is a minor contributor to global lightning, an opposite behavior is observed in the Pacific and other oceanic regions. More lightning is present during cold, La Niña conditions than during the warm, El Niño episodes. The annual distribution of global lightning is slightly offset from the equator into the Northern Hemisphere due to the north–south asymmetry of the land/ocean area ratio. Schumann resonance intensity variations suggest a southward (equator-ward) shift and satellite observations support this and show in addition an eastward shift in the global position during warm, El Niño episodes. The greatest lightning contrast between warm El Niño and cold La Niña episodes has been identified at the latitudes of descending dry air in the Hadley circulation. 相似文献
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