共查询到15条相似文献，搜索用时 250 毫秒
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LADCP观测和资料后处理的关键技术 总被引：4，自引：4，他引：4
针对LADCP这一崭新而又特殊的海流观测技术，系统地介绍了LADCP／CTD捆绑式测量、罗盘标定、测量设置和附加信息获取等LADCP观测中的主要技术问题。在对LADCP瓦迭式资料特点进行研究的基础上，阐释了LADCP资料后处理的关键技术：首先进行LADCP资料初处理和声速剖面校正，利用同ping剖面内相邻两水层的LADCP测量值之差等于两水层的真实速度之差这一特性，把LADCP的所有测量值转化为垂向切变流速，求出水柱内各水层的垂向切变率，对其按照一定的积分顺序进行深度积分，得到水柱内各水层相对于参考层的相对速度，利用底跟踪信息可以较直接地求出参考层的速度，也可以根据测量过程中LADCP和测船相对位置在入水时和出水时保持不变这一基本成立的假定通过GPS信息求出参考层的速度，从而得到整个水柱内各水层的绝对流速。为了提高处理结果的准确度，在资料后处理的每一处理步骤中都要特别注意相应的数据质量控制。 相似文献
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针对目前根据LADCP回波强度判断海底深度不准确,反演的流速剖面存在较大误差的情况,本文提出1个改进方法,通过综合利用LADCP的相关数参量及近海底处样本点数目随着深度的变化等信息,有效地判别海底深度,缩小与真实水深的差据,并且得到较为准确的近海底处的流速剖线信息,为研究近海底边界层内的动力过程提供了有效的观测数据。 相似文献
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下放式声多普勒海流剖面仪(LADCP)是20世纪90年代出现的一种海流剖面测量方式,能够快速获得大范围、全深度的海流剖面数据,在国内外有很广泛的应用。中科院声学所第一次将声通信部分加入LADCP中,完成了LADCP下放的实时监控。文中介绍了适用于LADCP通信特点的一种基于DS-CDMA的通信方法,完成了理论仿真,并通过进行相应的海试,验证了该方法的有效性。 相似文献
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自由投放式声学多普勒海流剖面（FADCP）观测以“自由落体”方式进行采样，其不依赖于测船钢缆牵引即可对全深度海流进行观测，观测稳定性较下放式声学多普勒海流剖面（LADCP）大幅提升，有效减少了观测值之中的不规则运动。2021年4月与9月在南海西沙海域开展的FADCP观测实验获得了两个断面包含16个站的海流及CTD资料。基于静置期间的真实底流观测，各站全深度的海流剖面采用剪切法获得，潜标附近站位剖面与潜标观测剖面相比，平均流速偏差为3 cm/s。观测断面捕捉到了西沙海域两个时期的气旋涡，其垂直结构比HYCOM模拟更精细，表层流与绝对地转流契合。研究表明，FADCP对测船要求低、数据质量高，其后处理简便且结果良好，但无法对特定水层实施补充观测。 相似文献
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ADCP观测得到的2008年4月吕宋海峡流速剖面结构 总被引：1，自引：0，他引：1
基于2008年4月22—26日吕宋海峡调查航次的下放式声学多普勒流速剖面仪(LADCP)和船载ADCP(SADCP)等观测资料,并采用潮波模式模拟结果去除潮流对观测资料的影响,观测结果表明:调查期间黑潮入侵南海的位置与1992年春季比较接近,其分支位于调查海区中部C2、C7、C8和C9站,表层黑潮在C8站分离为两支,分别流向C9和C2站,C9站北向流明显比C8站减弱。在C2站,黑潮分支位于400m层以浅,其最大西向流速为77cm/s,而在C7、C8和C9站黑潮分支位于500m层以浅,黑潮在入侵南海的过程中其核心深度逐渐变浅。上层黑潮明显作反气旋弯曲。本调查航次的观测结果在定性上支持吕宋海峡水交换有"三明治"垂直结构的特性。 相似文献
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为了研究西太平洋声散射层的垂向分布特征和日变化规律,分析了多波束测深系统的水体影像数据。观测结果表明,西太平洋存在着两个声散射层,一个声散射层位于0～200 m,另一个声散射层位于500～700 m,两个声散射层散射强度具有明显的日变化特征,上层散射层的散射强度呈现白天弱,夜晚强的特征,而下层散射层的散射强度日变化规律与上层相反,并且发现深散射层的厚度也存在日变化特征;分析了此种方法的优缺点,对以后声散射层的观测分析提供了新的思路。此外,利用同时下放的声速仪(SVP)的温度和深度数据对下放式声学多普勒流速剖面仪(LADCP)的观测结果进行了修正,得到了更为精确的声散射层垂向位置分布。 相似文献
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依据2012年ROSE航次船载ADCP和LADCP的观测数据,对南海秋季声散射层的垂向分布特征和日变化进行了分析;根据估算出的散射层中散射体的垂向迁移速度,对散射体类型进行了分析。观测结果表明,南海存在着2个声散射层,一个声散射层位于0~200m,散射强度具有显著的日变化特征,即白天弱,夜晚强;另一声散射层则处于300~500m的深度,其散射强度的日变化与另一个相反,白天较强,夜晚变弱。通过计算可得,散射体的垂向迁移,在傍晚时分运动方向向上,速度约为1.74cm/s;而凌晨左右运动方向向下,速度约为1.39cm/s。观测结果还表明,ADCP和LADCP的观测结果能够互相补充,更有利于对声散射层的细致研究。 相似文献
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Correction method for full-depth current velocity with lowered acoustic Doppler current profiler (LADCP) 总被引：1，自引：0，他引：1
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. 相似文献
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The results obtained with the use of a lowered acoustic Doppler current profiler (LADCP) are presented. The use of the LADCP from a vessel was the first in the history of the study of the Black Sea. The measurements were carried out in the northeastern Black Sea under the auspices of the Black Sea Ecosystem Recovery Program (BSERP) in May 2004. The effect of the computation parameters on the quality and accuracy of the calculations of velocity profiles was studied. It was shown that the use of optimal parameters and reliable navigation data and setting the instrument as close to the bottom as possible could essentially enhance the accuracy of the measurements. The current velocity calculations from the LADCP data were compared with the data on the vessel drift under calm weather. The accuracy of the calculations reached 6–8 cm/s. Recommendations on the choice of the optimal parameters for processing the data on the current velocity are presented. 相似文献
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Marika Marnela Bert Rudels K. Anders Olsson Leif G. Anderson Daniel J. Torres James H. Swift 《Progress in Oceanography》2008,78(1):1-11
To determine the exchanges between the Nordic Seas and the Arctic Ocean through Fram Strait is one of the most important aspects, and one of the major challenges, in describing the circulation in the Arctic Mediterranean Sea. Especially the northward transport of Arctic Intermediate Water (AIW) from the Nordic Seas into the Arctic Ocean is little known. In the two-ship study of the circulation in the Nordic Seas, Arctic Ocean - 2002, the Swedish icebreaker Oden operated in the ice-covered areas in and north of Fram Strait and in the western margins of Greenland and Iceland seas, while RV Knorr of Woods Hole worked in the ice free part of the Nordic Seas. Here two hydrographic sections obtained by Oden, augmented by tracer and velocity measurements with Lowered Acoustic Doppler Current Profiler (LADCP), are examined. The first section, reaching from the Svalbard shelf across the Yermak Plateau, covers the region north of Svalbard where inflow to the Arctic Ocean takes place. The second, western, section spans the outflow area extending from west of the Yermak Plateau onto the Greenland shelf. Geostrophic and LADCP derived velocities are both used to estimate the exchanges of water masses between the Nordic Seas and the Arctic Ocean. The geostrophic computations indicate a total flow of 3.6 Sv entering the Arctic on the eastern section. The southward flow on the western section is found to be 5.1 Sv. The total inflow to the Arctic Ocean obtained using the LADCP derived velocities is much larger, 13.6 Sv, and the southward transport on the western section is 13.7 Sv, equal to the northward transport north of Svalbard. Sulphur hexafluoride (SF6) originating from a tracer release experiment in the Greenland Sea in 1996 has become a marker for the circulation of AIW. From the geostrophic velocities we obtain 0.5 Sv and from the LADCP derived velocities 2.8 Sv of AIW flowing into the Arctic. The annual transport of SF6 into the Arctic Ocean derived from geostrophy is 5 kg/year, which is of the same magnitude as the observed total annual transport into the North Atlantic, while the LADCP measurements (19 kg/year) imply that it is substantially larger. Little SF6 was found on the western section, confirming the dominance of the Arctic Ocean water masses and indicating that the major recirculation in Fram Strait takes place farther to the south. 相似文献
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Currents in the Drake Passage are studied using the data of a hydrographic section along the Shackleton Transverse Ridge observed in November 2007. The distribution of the velocity component normal to the section was computed by two methods: (a) directly on the basis of the lowered acoustic Doppler current profiler (LADCP) data; (b) by the calculation of geostrophic currents based on the CTD data with estimating the depth averaged velocity on the basis of the LADCP data. The main results of the research are the relatively low estimated value of the Antarctic Circumpolar Current (ACC) transport, which accounts for 65–70% of the ACC transports in December 2003 and November 2005, and the confirmation of the existence of several abyssal currents confined to the deep passages of the bottom topography. 相似文献