• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Estuarine Coastal and Shelf Science >Winter storm-induced hydrodynamics and morphological response of a shallow transgressive shoal complex: Northern Gulf of Mexico
【24h】

Winter storm-induced hydrodynamics and morphological response of a shallow transgressive shoal complex: Northern Gulf of Mexico

机译：冬季风暴诱发的浅海侵入浅滩复合体的水动力和形态响应：墨西哥北部海湾

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Using extended deployments during seasons of low and high discharge from the Atchafalaya River, meteorological, hydrodynamic and bottom boundary layer parameters were monitored from Tiger and Trinity Shoal complex, off Louisiana coast, USA. During winter storms, the surface current speed measured at both shoals exceeded 0.5 m/s and the entire water column followed the prevailing wind direction. The current speed close to the bottom exceeded 0.3 m/s during high energy northerly winds. The mean water level in the shoal complex increased during southerly winds and decreased during northerly winds, such that the difference between wind set-up and set-down exceeded 0.7 m in Tiger Shoal and 0.6 m in Trinity Shoal during high energy frontal passages. The swell height was inversely correlated with mean water level, and increased during pre-frontal phase and decreased during post-frontal phase of winter storms. The sea (short waves) height responded quickly to wind direction and speed; and within a few hours after the wind shifted and blowing from the north, the sea height increased during both deployments. Bimodal wave frequency spectrum was observed during wind veering from southerly to northerly, when both sea and swell intensities were significant. The Tiger Shoal bed sediment texture transformed drastically, from mud to shell and shell hash assemblage, within a period of two weeks during the December 2008 deployment. Backscatter signal intensity from a Pulse Coherent Acoustic Doppler Profiler (PCADP) and its velocity estimates were used to determine the vertical extend and timing of mud resuspension and their eventual flushing out from the shoal environment, when exposed to high energy winter storm passages. The computed time frame for a total transformation of bottom sediment texture (from muddy bottom to shell and shell hash assemblage) was supported by the combined wave and bottom current induced shear stress at shoal bed. The bed samples collected from Tiger Shoal before and after the deployment in spring 2009 consisted of more than 80% shell and shell hash, which again confirmed a stable bottom as predicted from the PCADP data. However, the fine sand and mud dominated bed at Trinity Shoal was highly dynamic and experienced a few cm of ephemeral sediment deposition during the passage of each cold front, as revealed from the analysis of acoustic backscatter data from the PCADP. Suspended sediment concentration estimated from Optical Backscatterance Sensors (OBS) and PCADP were in good agreement during low river discharge events in December 2008; but significantly diverged during the spring 2009 deployment, when a high suspended sediment load was discharged into the shelf from the Atchafalaya River, and subsequently pushed farther offshore into the deployment sites by wind-induced strong currents during the passage of cold fronts. (C) 2015 Elsevier Ltd. All rights reserved.
机译：在从阿恰法拉雅河排放高，低流量的季节中，通过扩展部署，从美国路易斯安那州沿海的老虎和三位一体浅滩综合体监测了气象，水动力和底部边界层参数。在冬季风暴中，在两个浅滩上测得的地表流速均超过0.5 m / s，整个水柱都遵循盛行的风向。在高能量的北风中，接近底部的当前速度超过0.3 m / s。在南风中，浅滩综合体的平均水位在南风中增加，而在北风中则降低，因此在高能量的正面通道中，虎滩的风设置与降落之间的差异超过0.7 m，三位一体滩的风设置与降落之间的差异超过0.6 m。隆升高度与平均水位成反比，并且在冬季暴风雨的前额叶期增加，而在额叶后期减少。海（短波）高度对风向和风速反应迅速；在风向北移并吹拂后的几个小时内，两次部署期间的海面高度都增加了。当风向和南北向强烈时，从南向北转向时观察到双峰波频谱。在2008年12月的部署过程中，两周之内，老虎滩床层的沉积物质地从泥浆变成了贝壳，再经过贝壳哈希混合体急剧变化。来自脉冲相干声学多普勒剖面仪（PCADP）的反向散射信号强度及其速度估算值可用于确定泥浆重悬的垂直扩展和时间，以及当暴露于高能量的冬季风暴通道时，它们从浅滩环境中冲出的可能性。波浪和底部电流在浅滩层的组合剪切应力支持了底部沉积物质地（从泥泞的底部到壳和壳的哈希组合）总转变的计算时间框架。在2009年春季部署前后，从Tiger Shoal收集的床层样品包含80％以上的壳和壳散列，这再次证实了根据PCADP数据预测的稳定底部。但是，从PCADP的声向后向散射数据分析中可以看出，三位一体浅滩中由细砂和泥浆为主的床具有很高的动态性，并且在每个冷锋经过期间经历了几厘米的短暂沉积物沉积。根据光学反向散射传感器（OBS）和PCADP估算的悬浮泥沙浓度在2008年12月的低河流量事件中基本一致。但在2009年春季的部署过程中出现了很大的分歧，当时高的悬浮泥沙负荷从Atchafalaya河排放到了陆架上，随后在冷锋通过期间由风引起的强流将更远的海上推入部署地点。 （C）2015 Elsevier Ltd.保留所有权利。

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号