An upwelling case study on Florida's west coast
An upwelling case study on Florida's west coast
复制标题
DOI：
10.1029/2000jc900006
复制
发表时间：
2000-05
影响因子：
--
通讯作者：
R. Weisberg;B. D. Black;Zhenjiang Li
中科院分区：
文献类型：
--
作者：
R. Weisberg;B. D. Black;Zhenjiang Li
利用卫星海洋表面温度图像、现场海流、温度和海平面数据以及数值环流模式的组合，我们描述了在佛罗里达州西海岸观测到的一次上升流事件。尽管大陆架的特征无处不在，但对沿海上升流(或下降流)的描述通常因其发生的连续过程而变得复杂。对于所展示的案例研究，风很小，斜压背景流在事件发生前的几天里是稳定的。这些条件使得特定的风驱动上升流事件的演变可以看作是一个初值问题。资料和数值模式分析表明，海平面和海流的调整路径是典型的Ekman-地转路径。由于离岸Ekman输送，海平面下降，导致沿海岸急流的地转，而与之相关的Ekman层底部的陆上流动解释了表面出现冷水的原因。这一地表表现为一个细长的特征，以25米等深线为中心，从坦帕湾以北到基韦斯特，大约横跨佛罗里达半岛的一半。最冷的海水是在坦帕湾的近海观测到的，我们根据海岸线和等深线几何形状解释了这一局部最大上升流的区域。
Using a combination of satellite sea surface temperature imagery; in situ currents, temperature, and sea level data; and a numerical circulation model, we describe an upwelling event observed along Florida's west coast. Although ubiquitous features of continental shelves, descriptions of coastal upwellings (or downwellings) are generally complicated by the continuum of processes in which they occur. For the case study presented the winds were light, and the baroclinic background currents were steady for several days prior to the event. These conditions allow the evolution of a specific winddriven upwelling event to be viewed as an initial value problem. The data and the numerical model analysis show that the route of adjustment by the sea level and currents is a classical Ekman-geostrophic one. Sea level drops due to an offshore Ekman transport, causing a geostrophic alongshore jet, and the associated onshore flow within the bottom Ekman layer accounts for the appearance of cold water at the surface. This surface manifestation occurs as an elongated feature, centered about the 25 m isobath, that spans roughly half of the Florida peninsula from just north of Tampa Bay to Key West. The coldest water is observed offshore from Tampa Bay, and we explain this region of locally maximum upwelling on the basis of the coastline and isobath geometries.