Correction method for full-depth current velocity with lowered acoustic Doppler current profiler (LADCP)

A new method is presented to process and correct full-depth current velocity data obtained from a lowered acoustic Doppler current profiler (LADCP). The analysis shows that, except near the surface, the echo intensity of a reflected sound pulse is closely correlated with the magnitude of the difference in vertical shear of velocity between downcast and upcast, indicating an error in velocity shear. The present method features the use of echo intensity for the correction of velocity shear. The correction values are determined as to fit LADCP velocity to shipboard ADCP (SADCP) and LADCP bottom-tracked velocities. The method is as follows. Initially, a profile of velocity relative to the sea surface is obtained by integrating vertical shears of velocity after low-quality data are rejected. Second, the relative velocity is fitted to the velocity at 100–800 dbar measured by SADCP to obtain an “absolute” velocity profile. Third, the velocity shear is corrected using the relationship between the errors in velocity shears and echo intensity, in order to adjust the velocity at sea bottom to the bottom-tracked velocity measured by LADCP. Finally, the velocity profile is obtained from the SADCP-fitted velocity at depths less than 800 dbar and the corrected velocity shear at depths greater than 800 dbar. This method is valid for a full-depth LADCP cast throughout which the echo intensity is relatively high (greater than 75 dB in the present analysis). Although the processed velocity may include errors of 1–2 cm s⁻¹, this method produced qualitatively good current structures in the Northeast Pacific Basin that were consistent with the deep current structures inferred from silicate distribution, and the averaged velocities were significantly different from those calculated by the Visbeck (2002) method.     

基于PAADCP 的海流流速的误差分析及校正方法

为了更加合理、有效地利用海流测速数据,必须进行误差分解和校正。通过分析相控阵声学多普勒海流剖面仪(PAADCP)测试海流流速的原理,提出了海试数据粗差区别与动态校正的算法,采用小波多尺度分析方法,降低了系统误差和随机误差,建立了海流流速的误差分析与校正方法。利用海试实测的垂向流速数据,分析了一般情况下的海流流速的误差,得到垂向流速的均值±0.02 m/s,误差精确度小于0.23 m/s,验证了方法的有效性及合理性。所得算法和方法对于海流测速数据的实时处理和后处理具有实用价值。     

宁波,舟山内海域实测海流分析及潮流场的数值模拟

本文根据８０年代中后期所进行的潮位、现场测流资料分析宁波、舟山内海域的潮运动及海流特征，并进行了潮流场的数值模拟计算。     

北黎湾及邻近海域潮流数值计算

建立北黎湾及邻近海域二维潮流数值模型,重现该海域潮波及潮流的分布规律,计算得到m1分潮和M2分潮的同潮时线与等振幅线、潮流椭圆,m1与M2合成的潮致欧拉余流、最大潮流和不同时刻潮流场分布。     

深海剖面测流潜标系统设计及姿态分析

结合深海海流剖面测量实际应用,介绍了潜标系统的设计中须注意的几个问题。针对绳索和不同形状的潜标系统测量单元,给出了静力计算和姿态分析的步骤与方法。根据测量要求,在假定的海流剖面环境下,计算了各潜标单元在海水中的位置、倾斜以及潜标系统的浮力配置和锚块配重。该方法对于潜标设计具有实际参考意义。     

基于油气平台的海冰雷达监测图像处理及冰速测量

对海冰的运动规律进行精确、连续和长周期的实时监测有助于海冰热力学和动力学的研究,也可保障冰区生产活动的安全进行。针对辽东湾海冰的运动特点和工程需求,在JZ20-2油气平台上建立了海冰雷达监测系统。采用数字图像处理技术对海冰雷达监测图像进行了分析和软件开发,可对海冰密集度、速度和冰块面积等海冰参数进行提取。采用该海冰雷达监测系统和数字图像处理软件,在2011-2012年冬季对该海域的海冰运动规律进行了全冰期的连续监测,在此基础上重点对海冰速度的雷达图像监测结果进行了分析,讨论了海冰速度场分布以及连续48 h的变化过程。以上结果为海冰的生消运移规律研究和油气作业区的海冰管理工作提供了可靠的现场监测数据。对海冰雷达现场监测及数字图像处理中的问题及改进方法进行了讨论。     

罗源湾海岸盐沼悬沙粒度及沉降速率的观测和分析

海岸盐沼对环境变化的响应非常敏感,是研究全球变化和人类活动对海岸带环境影响的典型区域之一。影响盐沼演化过程的一个非常重要的因素就是水体悬沙特性[1]。在沿岸水域环境中,有机和无机的细颗粒悬沙在物理和化学的作用下絮凝成大颗粒的絮凝体,其粒径和沉降速率通常是分散细颗粒悬沙的好几倍,因此絮凝过程基本上改变了细颗粒悬沙的水动力行为过程[2]。絮凝体因相对分散颗粒物有较高的沉降速率,水中的悬沙更容易沉降到滩面,控制着水体中的细颗粒物质的沉降通量[3]。