Dynamics of the Chesapeake Bay outflow plume: Realistic plume simulation and its seasonal and interannual variability
Dynamics of the Chesapeake Bay outflow plume: Realistic plume simulation and its seasonal and interannual variability
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DOI：
10.1002/2015jc011191
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发表时间：
2016-02
影响因子：
--
通讯作者：
Long Jiang;Meng Xia
中科院分区：
文献类型：
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作者：
Long Jiang;Meng Xia
针对切萨皮克湾及其邻近的沿海海洋实施了三维非结构化网格有限体积沿海海洋模型（FVCOM），以描绘真实的切萨皮克湾流出羽流（CBOP）及其季节和年际变化。应用适当的水平和垂直分辨率，该模型在匹配 2003 年至 2012 年的观测水位、温度和盐度方面表现出相对较高的技能。通过将输出与 HF 雷达电流测量、早期现场观测以及 MODIS 和 AVHRR 卫星图像进行比较，验证了模拟的表面羽流结构。根据模型快照和卫星图像中CBOP的方向、形状和大小，检测到五种实时羽流行为，这意味着风和河流流量的强烈调节。除了间歇性羽流调制之外，CBOP 的水平和垂直结构还表现出季节和年际时间尺度的变化。从季节上看，1个月滞后的河流流量是地表羽流面积变化的主要原因，而羽流厚度主要与风级相关。在年际尺度上，河流流量是地表羽流面积和深度变化的主要来源；然而，南风也影响了离岸羽流的深度。此外，北大西洋涛动等大规模气候变化可能会通过改变风和上升流动力学来长期影响羽流特征，这凸显了了解气候变化对浮力羽流（如CBOP）影响的必要性。
The three-dimensional unstructured-grid Finite Volume Coastal Ocean Model (FVCOM) was implemented for Chesapeake Bay and its adjacent coastal ocean to delineate the realistic Chesapeake Bay outflow plume (CBOP) as well as its seasonal and interannual variability. Applying the appropriate horizontal and vertical resolution, the model exhibited relatively high skill in matching the observational water level, temperature, and salinity from 2003 to 2012. The simulated surface plume structure was verified by comparing output to the HF radar current measurements, earlier field observations, and the MODIS and AVHRR satellite imagery. According to the orientation, shape, and size of the CBOP from both model snapshots and satellite images, five types of real-time plume behavior were detected, which implied strong regulation by wind and river discharge. In addition to the episodic plume modulation, horizontal and vertical structure of the CBOP exhibited variations on seasonal and interannual temporal scales. Seasonally, river discharge with a 1 month lag was primarily responsible for the surface plume area variation, while the plume thickness was mainly correlated to wind magnitude. On the interannual scale, river discharge was the predominant source of variability in both surface plume area and depth; however, the southerly winds also influenced the offshore plume depth. In addition, large-scale climate variability, such as the North Atlantic Oscillation, could potentially affect the plume signature in the long term by altering wind and upwelling dynamics, underlining the need to understand the impacts of climate change on buoyant plumes, such as the CBOP.