| Li Chunyan,Boswell Kevin M.,Chaichitehrani Nazanin,Huang Wei,Wu Renhao. 2019. Weather induced subtidal flows through multiple inlets of an arctic microtidal lagoon. Acta Oceanologica Sinica, 38(3):1－16 |
| Weather induced subtidal flows through multiple inlets of an arctic microtidal lagoon |
| 有多个出口的北极地区微潮咸水湖的天气导致的次潮流 |
| Received:October 10, 2018 |
| DOI：10.1007/s13131-019-1361-2 |
| Key words:wind-driven flows multiple inlets micro-tidal numerical model experiments counter-wind flows quasi-steady state |
| 中文关键词: 风生流 多出口河口 微潮 数值实验 逆风流 准静态平衡 |
| 基金项目:The National Key R & D Project of China under contract No. 2017YFC1404201; the USA North Pacific Research Board Project under contract No.1229 and the USA Bureau of Ocean Energy Management Awards under contract Nos M12PG00024 (ACES) and M12PG00018 (Arctic EIS). |
| Author Name | Affiliation | E-mail | | Li Chunyan | Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70803, USA | | | Boswell Kevin M. | Department of Biological Sciences, Florida International University, North Miami, FL 33181, USA | | | Chaichitehrani Nazanin | Horn Point Laboratory, Center for Environmental Science, University of Maryland, Cambridge, MD 21613, USA | | | Huang Wei | Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70803, USA | | | Wu Renhao | College of Marine Sciences and Technology, Zhejiang Ocean University, Zhoushan 316022, China | mikewu@zjou.edu.cn |
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| Abstract: |
| Estuarine processes in the arctic lagoons are among the least studied but important subjects, especially considering the rapid warming of arctic water which may change the length of ice-free period in the summer. In this paper, wind-driven exchange flows in the micro-tidal Elson Lagoon of northern Alaska with multiple inlets of contrasting widths and depths are studied with in situ observations, statistical analysis, numerical experiments, a regression model on the basis of dynamics, and remote sensing data. Water velocity profiles were obtained from a bottom deployed acoustic Doppler current profiler (ADCP) in the northwestern Eluitkak Pass connecting the Beaufort Sea to the Elson Lagoon during a 4.9 day ice-free period in the summer of 2013. The subtidal flow is found correlated with wind (R2 value ~96%). Frequently occurring east, northeast and north winds from the arctic atmospheric high-and low-pressure systems push water from the Beaufort Sea into the lagoon through the wide inlets on the eastern side of the lagoon, resulting in an outward flow against the wind at the narrow northwestern inlet. The counter-wind flow is a result of an uneven wind forcing acting through the asymmetric inlets and depth, an effect of "torque" or vorticity. Under northwest wind, the exchange flow at the northwestern inlet reverses its direction, with inward flows through the upwind northwestern inlet and outward flows through the downwind eastern inlets. A regression model is established based on the momentum equations and Taylor series expansions. The model is used to predict flows in July and August of 2015 and July of 2017, supported by available Landsat satellite images. About 73%-80% of the time the flows at Eluitkak Pass are out of Elson Lagoon for the summer of 2015 and 2017. Numerical experiments are conducted to corroborate the findings and illustrate the effects under various wind conditions. A quasi-steady state balance between wind force and surface pressure gradient is confirmed. |
| 中文摘要: |
| 北极地区的咸水湖连接着极地的河流和极地海洋。与其相关的河口动力学过程至今未被广泛深入探讨。考虑到全球气候变化的影响，该地区的夏季无冰期可能会变长，使得风生环流的重要性更加突出。本文讨论位于北阿拉斯加的美国最北部的比邻Beaufort Sea的有着多个出海口的咸水湖中风生交换流的动力学过程。该研究区域是只有微弱潮汐的Elson Lagoon。其多个出海口的特征对比鲜明：有特别窄又相对深的出口，也有很浅很宽的出口。我们采用现场观测、统计分析、数值实验、回归模型、以及遥感资料做一个综合性的分析。观测资料有大约4.9天，主要通过多普勒声学测流仪，取自2013年夏季的无冰期。仪器放置在Elson Lagoon最西北边的窄的出口。结果显示，次潮流（subtidal flow）与风有很强的相关性（R2值~78%到96%）。常见的极地高压（反气旋）和低压（气旋）以及相应的大气锋面产生的东风、东北风、和北风，将Beaufort Sea的水从东边较宽的出海口推入湖中，进而产生西北边窄的出口处的较强逆风流，流出咸水湖。此逆风流是由不对称出口引起的风生力矩所造成的。在西北风的情况下，西北部出口处的流是从Beaufort Sea流进咸水湖，又从东边的宽出口流出到Beaufort Sea。这里，根据动力学方程和泰勒级数展开导出一个关系式，然后对风生流做了统计回归分析，并计算了2015年7月和八月的风生交换流。其结果得到了高分辨率卫星图像的证实。我们采用数值模拟对不同的风的情况做讨论进一步验证我们的理论和结论。并进一步验证了在其它几个河口发现的风生水位坡度与风应力的准平衡。 |
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