• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Variability and structure of currents over the Texas-Louisiana shelf: A view from a shipboard acoustic Doppler current profiler.
【24h】

Variability and structure of currents over the Texas-Louisiana shelf: A view from a shipboard acoustic Doppler current profiler.

机译：Texas-Louisiana架上电流的可变性和结构：船上声学多普勒电流剖面仪的视图。

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

The structure and variability of currents over the Texas-Louisiana shelf are described using ADCP measurements, hydrographic data, and moored current meter records taken during February, July and November of 1993. For these three surveys, complex EOF analysis of ADCP velocity profiles demonstrates that the first three empirical modes account for more than 90 percent of the observed energy along the 50-m and 200-m isobaths over the shelf. The dominant EOF modes are nearly barotropic. The second empirical modes infer that the baroclinic motion during February is weakest among these three cruises.; The vertical shears of geostrophic and ADCP current were compared using bivariate EOF analysis to assess the validity of geostrophic approximation over this shelf. The first and third EOF modes indicate prominent consistency of these two shears, but the second modes suggest that the current measurements contain significant ageostrophic components. These ageostrophic components in the ADCP data presumably result from high-frequency current fluctuations and frictional effects.; Calculations of transverse and longitudinal velocity correlations versus separation distance were made from the near surface ADCP measurements. From these, the correlation of an associated geostrophic streamfunction can be inferred. For the along-shelf transects, the spatial correlation scales of streamfunction are 32 km during July and 35 km during November. For the February survey, the correlation scale for the cross-shelf transects is 19 km. This coincides with the scale of geopotential anomaly deduced from the hydrographic data, but the scale for the along-shelf transects is shorter.; For the majority of the shelf, data from current meter moorings indicate that low-frequency currents are stronger than high-frequency currents during February and July. The high-frequency currents are stronger in the eastern shelf than the western shelf. Optimal estimation of low-frequency currents was implemented by the statistical objective analysis of ADCP velocity measurements. Results agree well with the circulation pattern inferred from the geopotential anomaly for July and November. However, due to the strong temporal variability of the currents, a synoptic flow field for the February cruise was not achieved.
机译：使用ADCP测量，水文数据和1993年2月，7月和11月的系泊电流计记录来描述德克萨斯-路易斯安那架子上电流的结构和变化性。对于这三个调查，对ADCP速度剖面的复杂EOF分析表明：前三个经验模式占沿架子上50 m和200 m等深线观察到的能量的90％以上。主要的EOF模式几乎是正压模式。第二种经验模式推断，在这三个巡航中，二月份的斜压运动最弱。使用双变量EOF分析比较了地转和竖向剪切力，以评估该架子上地转近似的有效性。第一种和第三种EOF模式表明这两个剪切具有突出的一致性，但是第二种模式表明当前的测量结果包含明显的年龄营养成分。 ADCP数据中的这些非营养成分可能是由高频电流波动和摩擦效应引起的。从近地表ADCP测量值计算出横向和纵向速度相关性与分离距离之间的关系。由此，可以推断出相关的地转流功能的相关性。对于陆架样带，流函数的空间相关尺度在7月为32 km，11月为35 km。对于2月的调查，跨架横断面的相关标度为19 km。这与从水文数据推断出的地势异常规模相吻合，但沿陆架横断面的规模更短。对于大多数架子，来自电流表系泊设备的数据表明，在2月和7月期间，低频电流强于高频电流。东部大陆架的高频电流强于西部大陆架。低频电流的最佳估计是通过ADCP速度测量的统计客观分析来实现的。结果与从七月和十一月的地势异常推断的环流模式非常吻合。但是，由于洋流的强烈时间变化性，未能实现二月巡航的天气流场。

著录项

  • 作者

    Chen, Hsien-Wen.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Physical Oceanography.
  • 学位 Ph.D.
  • 年度 1995
  • 页码 103 p.
  • 总页数 103
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋物理学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
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