2009/2010年El Niño事件变化特征及其机理
Variational characteristics analyses of the El Niño event in 2009/2010
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摘要: 应用TAO(Tropical Atmosphere Ocean project)热带太平洋实测海温和风场资料,分析研究了发生在2009/2010年的El Niño事件的变化特征,讨论了此次El Niño事件发生过程中,赤道东、西太平洋次表层异常海温的变化特征及其传播过程,特别是对赤道太平洋次表层异常海温变化的过程进行了深入分析研究。结果表明,2009/2010年赤道太平洋的增温主要存在两个不同的过程。一是西太平洋暖池(WPWP)区域次表层异常海温沿温跃层东传,以及赤道东太平洋的局地增温导致赤道东太平洋上层海洋增温过程。二是中西太平洋区域的异常西风加强,使得在中太平洋产生强的风场辐合,导致表层较高海温下传(downwelling),使中太平洋次表层异常海温再次升高,从而导致赤道东太平洋表层出现第2次增温过程。这一研究结果表明,2009/2010年赤道太平洋增温过程与以往的El Niño事件过程有所不同,此次事件不仅包括了经典的暖事件形成过程,同时也具备了中部型El Niño(Central Pacific Pattern El Niño,简称CPP El Niño)事件的特征。此次异常海温信号不仅与热带太平洋次表层异常海温信号通道中的异常海温循环有关,还与中西太平洋区域的大气风场异常强迫引起的中太平洋次表层异常海温信号增强过程存在密切关系。Abstract: The variability of one warming event which occurred on the equatorial Pacific Ocean in the summer 2009/2010 was analyzed using the temperature and wind data from tropical atmosphere ocean (TAO) project dataset. The variation and propagation of anomalous subsurface ocean temperature in equatorial Pacific were discussed in the process of El Niño event. The results indicated that there were two different mechanisms in eastern equatorial Pacific warming process in the summer 2009/2010. One was the propagation of the anomalous subsurface ocean temperature along the thermocline from west to east Pacific and the local warming in eastern Pacific. The other was the increase of west wind in the western Pacific warm pool (WPWP) made the wind convergence. This convergence conduced to the warm water downwelling from surface to subsurface. Then the subsurface water was warm again and eastward propagated. These results indicated that the anomalous temperature from the subsurface signal cycle in the tropical Pacific, the local warming in the eastern equatorial Pacific due to the decrease of wind and the atmosphere forcing in WPWP were the main reasons which induced the warmer event in 2009/2010.
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Key words:
- TAO real data /
- WPWP /
- CPP El Niñ /
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