走航ADCP数据处理与质量控制方法研究

介绍了声学多普勒流速剖面仪(ADCP)测流的基本原理和利用ADCP自带软件进行原始数据处理过程中需要设置的关键参数;着重论述了ADCP数据标准化处理和质量控制方法的研究,并利用实测数据对研究方法进行了验证。结果表明,本文研究的方法针对ADCP底跟踪观测数据处理效果良好,并可为GPS跟踪模式下的ADCP数据处理和质量控制提供可行的技术参考。     

台风期间浮标和潜标上ADCP的空间变化、数据误差及校正#br#

基于南海北部浮标和潜标的声学多普勒流速剖面仪（ADCP）数据,通过一套几何算法计算了台风海鸥（1415）期间ADCP的空间变化和流速误差,并进行数据校正。浮标上,台风过后ADCP的水平位移最大可达2.61 km,水平流速误差最大可达0.27 m/s,垂向流速误差最大仅为5×10^-4 m/s;温跃层流速校正值在台风过后显著大于流速测值,这表明水平校正对于温跃层流速的质量控制很重要。潜标上,ADCP最大垂向位移增量为179 m,最大绳子倾角为35°,最大水平位移为1.5 km; ADCP水平流速误差和倾角误差都很小,在数据校正中可忽略不计,但对台风过后中层流速的垂向校正不能忽略。     

珠江口外走航ADCP资料的系统误差订正与质量控制

在对珠江口外2006年冬季航次走航ADCP观测资料处理中发现用Joyce的方法不能有效地订正系统误差,其原因在于订正角与航速、船艏向相关。给出了一个订正角为船艏向余弦的拟合函数,得出良好的订正结果。分析了VmDas软件处理流速结果的精度,给出了系统误差识别的方法。发现观测资料中一些不能为VmDas软件识别的错误数据,分析了海况对观测资料的影响,提出了观测资料质量控制与误差订正的一套程序。     

基于南极科考数据的ADCP深度订正实验

声学多普勒流速剖面仪由于其结构、原理及观测环境等因素,其流速观测结果与海水实际深度的匹配存在较大偏差。采用第31次南极科考实测ADCP及XCTD数据,通过计算实际声速,对ADCP层深计算公式进行了订正实验,使流速观测数据与其所对应的实际深度重新匹配。结果显示,深度订正值随深度的增加而增大,至700m处,最大订正值可达16m。相应的流速和流向也随深度的订正有大幅度的改变,而且,无论是深度还是流速和流向,其订正值均由低纬向高纬,逐渐增大。     

底边界层水沙观测系统和应用

利用现代先进的光学和声学测量仪器(ADP、PC-ADP、ADV、OBS等),组制四角架观测系统用于底边界层的水沙观测.此观测系统既可获取垂向流速场,更可获取常规水文观测难以获取的高分辨率的近底流速、近底单点紊动过程、近底温盐沙和波浪过程.利用此观测系统于2007年8月在长江口北槽最大浑浊带内进行了实地观测.分析四角架观测数据与同步船测底部数据表明,四角架观测系统在近底(特别是底部明显分层)观测时表现出明显优势.常规水文观测测得底部含沙量一般只相当于距底70～120 cm高度含沙量;船测底部最大含沙量为5.8 kg/m 3,而架测距底30 cm处最大含沙量有25 kg/m 3;近底含沙量较高时往往出现强分层,强分层时实测距底30 cm处含沙量可达距底120 cm处含沙量的5倍;船测底部流速比架测距底30 cm处流速平均偏大45%;但距底30 cm处最大流速仍可达1.2 m/s.船测数据也验证了四角架观测数据的正确性.     

洋浦港附近冬季潮、余流特征分析

洋浦是典型的日潮区,潮型判别系数是7.32;最大潮流流速都出现在涨潮的北向流中,最大潮流速度为70cm/s.余流的表、中、底30d平均流向依次为188(°)、153(°)和95(°).表、中、底30d平均余流流速值依次为8.7、8.5和4.1cm/s.冬季余流的形成,主要受北部湾风生环流控制.     

基于三维调和分离的同安湾口门断面冬季潮流和余流特征的分析

利用同安湾口门断面走航ADCP观测数据,采用基于高斯基函数的Candela空间插值方法,对海流进行空间三维的调和分离,并对分离的各分潮流与余流进行流场的回归检验分析,F(α=0.01)检验显示流场的回归效果显著.观测期间同安湾口门断面平均潮差为5.15 m,最小潮差4.38m,最大潮差5.98 m,断面上涨落潮最大流速分别为92.3、80.3 cm/s,潮流特征分析表明,同安湾口门断面的潮流运动形式为往复流,以半日潮流为主,约占70%潮流信息,潮流流速从海表面向海底递减.余流最大值为12.5 cm/s,空间分布上将同安湾口门断面一分为二形成北进南出的余流进出通道,这与以往余流格局的认识相符.     

底部浮泥表层推移速度分布的ADCP—GPS估测方法

ADCP对底跟踪走航观测的流速数据中包含水体底部浮泥、底沙运动信息,对比GPS定位方法算出的水体流速数据可以分离出浮泥相对于GPS定位的运动信号,从而达到对底质推移观测的目的。     

走航ADCP观测资料质量控制方法及应用

为完善目前走航ADCP观测资料质量控制尚未形成统一流程的问题,将走航ADCP观测资料质量控制归纳为船速获取、声速校正、偏角校正以及剖面数据处理四个主要步骤,并制定了一套较为系统的走航ADCP观测资料质量控制流程。以渤海辽东湾红沿河核电站周边海域船载走航ADCP观测为例,按照提出的流程进行走航ADCP观测资料的质量控制。通过对比原始观测数据,质量控制后的结果表明u分量流速剔除了23.56%的低可信度数据,而v分量流速剔除了25.96%的低可信度数据。10 m与15 m水深处的质量控制前后的流速-频数直方图表明,本文提出的流程能有效地降低观测随机性的影响。     

舟山海域高频地波雷达表层流探测试验

2015年4月7-30日,在浙江省舟山近海海域开展了“嵊山-朱家尖”小型阵列变频高频地波雷达系统的海上比测试验,通过雷达观测数据与定点ADCP海流资料的比对检验了地波雷达表层流探测性能。径向流比对结果显示,测点与雷达法向夹角越小,距离雷达距离越近,径向流比测结果越好,雷达探测的结果越可靠。嵊山站径向流与ADCP观测结果的各站总体平均误差为7.98 cm/s,平均均方根误差为15.34 cm/s,平均相关系数为0.89,朱家尖站径向流与ADCP观测结果的各站总体平均误差为6.24 cm/s,平均均方根误差为12.36 cm/s,平均相关系数为0.81。根据矢量流比对结果显示,矢量流速与ADCP观测结果的各站总体平均误差为4.82 cm/s,平均均方根误差为15.03 cm/s,平均相关系数为0.44。设置在嵊山、朱家尖两个雷达站双站探测的核心区域（两个雷达站连线的中垂线上,并且与两个雷达站构成一个近似直角三角形）的站点比测结果更加理想,当流速大于0.25 m/s时,对于核心区域平均后的流向均方根误差为24.9°。     

滨海核电站取水口精细流场测量的设计与实例

冷源取水安全是核电运行安全的重要部分,会受到多种海洋堵塞物的威胁。为科学支撑滨海核电站取水口堵塞物防治工作,亟须掌握取水口的精细流场。走航和定点相结合的测量方式可同时获取流场的时空变化特征,适用于滨海核电站取水口精细流场的测量;走航测量宜采用具有底跟踪功能的ADCP,该设备具有测量精度高和数据处理简便的优点,然而在使用中应注重规范性以减少测量误差;以潮流为主的海域在涨急和落急时段的流场较稳定,在这段时间内进行走航数据插值可得到涨急和落急时段的精细流场;应用该方案获取某滨海核电站取水口的精细流场,测量结果显示取水口的流场较复杂,小范围流场受取水影响显著,呈现非潮流特征。     

Comparison of surface current variations observed by TOPEX altimeter with TOLEX-ADCP data

Variations of surface current velocity derived by the TOPEX altimeter are compared with data from Tokyo-Ogasawara Line Experiment (TOLEX)-Acoustic Doppler Current Profiler (ADCP) monitoring for a period from October 1992 to July 1993. Since the locations of ADCP ship track and TOPEX altimeter ground tracks do not coincide with each other, and the temporal and spatial sampling are also different between the ADCP and altimeter observations, re-sampling, interpolation and smoothing in time and space are needed to the ADCP and altimeter data. First, the interpolated TOPEX sea surface height is compared with sea level data at Chichijima in the Ogasawara Islands. It is found that aliasing caused by the tidal correction error for M2 constituent in the TOPEX data is significant. Therefore, comparison of the TOPEX data with the TOLEX-ADCP data is decided to be made by using cross-track velocity components of the surface current, which are considered to be relatively less affected by the errors in the tidal correction. The cross-track velocity variations derived from the TOPEX sea surface heights agree well with those of the ADCP observations. The altimeterderived velocity deviations associated with transition of the Kuroshio paths coincide with the ADCP data. It is quantitatively confirmed that the TOPEX altimeter is reliable to observe the synoptic variations of surface currents including fluctuations of the Kuroshio axis.     

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.     

ADCP application for long-term monitoring of coastal water

Three kind of application of ADCP is reported for long-term monitoring in coastal sea. (1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed at MT (Marine Tower) Station of Kansai International Airport in the Osaka Bay, Japan. The correlation between the turbidity and echo intensity in the surface layer is not good because air bubbles generated by breaking wave are not detected by the turbidity meter, but detected well by ADCP. When estimating the turbidity consists ofplankrton population from echo intensity, the effect of bubbles have to be eliminated. (2) Monitoring stirring up of bottom sediment. The special observation was carried out by using following two ADCP in the Osaka Bay, One ADCP was installed upward on the sea. The other ADCP was hanged downward at the gate type stand about 3 m above from the bottom. At the spring tide, high echo intensities indicating the stirring up of bottom sediment were observed. (3) The monitoring for the boundary condition of water mixing at an estuary. In summer season, the ADCP was set at the mouth of Tanabe Bay in Wakayama Prefecture, Japan. During the observation, water temperature near the bottom showed remarkable falls with interval of about 5～7d. When the bottom temperature fell, the inflow current with low echo intensity water appears at the bottom layer in the ADCP record. It is concluded that when occasional weak northeast wind makes weak coastal upwelling at the mouth of the bay, the combination ofupwelling with internal tidal flow causes remarkable water exchange and dispels the red tide.     

船载ADCP测量误差的因素分析和校正方法

系统归纳和分析了引起船载ADCP测量误差的主要因素和校正方法。结合实际经验对ADCP资料后处理中的难点问题提出了解决方案,并且取得了良好的结果。