New perspectives on Natal Pulses from satellite observations
New perspectives on Natal Pulses from satellite observations
复制标题
DOI：
10.1029/2010jc006866
复制
发表时间：
2011-07
影响因子：
--
通讯作者：
M. Rouault;P. Penven
中科院分区：
文献类型：
--
作者：
M. Rouault;P. Penven
[1] 利用6年多的高频海面温度（SST）图像来追踪纳塔尔北部海湾和伊丽莎白港之间厄加勒斯海流近岸锋面的扰动情况。选定的案例研究以及应用于SST数据的锋面检测算法为纳塔尔脉冲的动力学以及厄加勒斯海流北部的变化性提供了一些新的见解。在测量期间，厄加勒斯海流近岸锋面的路径没有表现出任何季节性。相反，厄加勒斯海流近岸锋面的大幅偏移主要是由从纳塔尔海湾和爱德华港地区到伊丽莎白港的离岸气旋式弯曲的间歇性移动所主导。SST图像显示，随着纳塔尔脉冲向下游推进，它们与地形相互作用形成次生离岸弯曲，这些次生弯曲在原始扰动的背风处传播。随着时间的推移，这些次生弯曲消散，重新融入原始的纳塔尔脉冲，或者从厄加勒斯海流脱离。厄加勒斯海流近岸路径的波动在所有断面并不显示相同的频率特征。从纳塔尔北部海湾到爱德华港，纳塔尔脉冲的规模和频率都增加，而在爱德华港以南，纳塔尔脉冲的数量减少。在伊丽莎白港，观测到的纳塔尔脉冲数量比之前的估计要少，平均每年为1.6个纳塔尔脉冲。
[1] More than 6 years of high-frequency sea surface temperature (SST) imagery are used to follow perturbations at the inshore front of the Agulhas Current, between the northern Natal Bight and Port Elizabeth. Selected case studies as well as a front detection algorithm applied to the SST data provide some new insights into the dynamics of Natal Pulses and the variability of the northern Agulhas Current. Over the measurement period, the path of the Agulhas Current's inshore front does not exhibit any seasonality. Instead, large excursions in the Agulhas Current's inshore front are dominated by the intermittent passage of offshore cyclonic meanders from the Natal Bight and Port Edward regions to Port Elizabeth. SST imagery reveals that as they progress downstream, Natal Pulses interact with the topography to form secondary offshore meanders which propagate in the lee of the original perturbation. Over time, these secondary meanders dissipate, remerge with the original Natal Pulse, or detach from the Agulhas Current. Fluctuations in the Agulhas Current inshore path do not display the same frequency characteristics at all transects. From the northern Natal Bight to Port Edward both the size and frequency of Natal Pulses increases, while south of Port Edward the number of Natal Pulses decreases. At Port Elizabeth, the number of Natal Pulses observed is lower in comparison to previous estimates, with an average of 1.6 Natal Pulses per year.