Upper equatorial Atlantic variability during 2002 and 2005 associated with equatorial Kelvin waves
Upper equatorial Atlantic variability during 2002 and 2005 associated with equatorial Kelvin waves
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DOI：
10.1029/2008jc005101
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发表时间：
2009-03
影响因子：
--
通讯作者：
Verena Hormann;P Brandt
中科院分区：
文献类型：
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作者：
Verena Hormann;P Brandt
在系泊（35度W，0度和23度W，0度）和卫星观测的基础上，我们对比了2002年和2005年赤道上大西洋的变化。对北半球夏季冷舌年际变率的检查显示，2002年（2005年）发生了一次暖（冷）事件，西风缓和（增强），赤道潜流（EUC）嵌入在西经23度的较浅（较深）温跃层中。在这两年，2002年和2005年，赤道开尔文波是目前在系泊观测20摄氏度的等温线深度异常和动态高度异常。全流域海面高度异常被用来推导赤道开尔文波模式。这种模式的时间演变是回归分析的基础，以调查相关的海洋变化：与2002年异常强烈的波活动相比，赤道开尔文波在2005年普遍较弱。赤道Kelvin波对纬向速度异常的主要影响在23 ° W，0度是明显的远低于EUC核心。它们对冷舌海表面温度的直接影响很小，但对赤道温跃层斜率有影响。在2002年（2005年）冷舌开始之前，赤道开尔文波的存在与平坦（陡峭）的温跃层斜率有关，这对于EUC核心在23 ° W处变浅（加深）至关重要，并且可能是暖（冷）事件发展的先决条件。
On the basis of moored (35 degrees W, 0 degrees and 23 degrees W, 0 degrees) and satellite observations, we contrast the upper equatorial Atlantic variability during 2002 with those during 2005. Inspection of the interannual boreal summer cold tongue variability revealed a warm (cold) event in 2002 (2005), with relaxed (intensified) winds in the west and the Equatorial Undercurrent (EUC) embedded in a shallower (deeper) thermocline at 23 degrees W. During both years, 2002 and 2005, equatorial Kelvin waves are present in moored observations as 20 degrees C isotherm depth anomalies and dynamic height anomalies. Basin-wide sea surface height anomalies are used to derive an equatorial Kelvin wave mode. The time evolution of this mode represents the basis for a regression analysis to investigate related oceanic variability: Compared to the exceptionally strong wave activity in 2002, equatorial Kelvin waves were generally weaker during 2005. The main effect of equatorial Kelvin waves on zonal velocity anomalies at 23 degrees W, 0 degrees is evident well below the EUC core. Their direct influence on cold tongue sea surface temperature is small, but they are found to affect the equatorial thermocline slope. Prior to the cold tongue onset in 2002 (2005), the presence of equatorial Kelvin waves is associated with a flattened (steeper) thermocline slope that is crucial for the shallowing (deepening) of the EUC core at 23 degrees W and that might precondition the development of the warm (cold) event.