【作者】 柯灏；

【导师】 赵建虎； 田淳；

【作者基本信息】 武汉大学 ， 大地测量学与测量工程， 2012， 博士

【摘要】 海洋无缝垂直基准及其建立是近年来海洋测绘研究领域的一个热点问题,也是一个难点。海洋无缝垂直基准是海洋、内陆江河流域以及水陆交界区域测量活动的垂直起算基准,具有①连续、无缝；②稳定,一经确定后不得变化；③符合人类海洋测绘等相关活动的使用习惯；④易与其它垂直基准进行转换等四大特征。随着国家对海岸带、江河流域的浅滩等水陆交界区域开发和利用的日益加大,建立现代化的海洋无缝垂直基准已是海洋测绘发展、国家经济建设的内在需求和必然趋势,可为我国海岸线的界定、数字海岸带和国防经济建设等提供重要的理论依据和基础保障。目前海洋无缝垂直基准的建立仍存在着一系列关键性难题。如选用何种垂直基准用来建立海洋无缝垂直基准为最优,建立前如何对原始数据实施预处理,采用何种无缝垂直基准构建方法以及同其它垂直基准之间的转换关系如何确定等。为此,本文在系统总结国内外海洋无缝垂直基准研究现状的基础上,提出了多项新思路、新模型和新方法,最终实现了局域海洋无缝垂直基准面的构建以及基准面间的相互转换。主要工作及创新之处体现在：(1)用于构建海洋无缝垂直基准的垂直基准面选择系统的比较和分析了(似)大地水准面、参考椭球面、平均海平面和深度基准面四种海洋测绘中常用的垂直基准面的特点,认为(似)大地水准面作为陆地高程基准,虽具有连续、无缝和光滑等特征,但其反映的是一个重力等位面,适用于陆地高程基准,而不适合作为海洋垂直基准；参考椭球面为几何面,尽管数学模型简单,且同样具有连续、无缝和光滑等特征,但缺少物理意义,也不符合海洋测绘中海图高标定习惯；平均海平面由于地域和时间的不同而存在着差异,且无法保证船舶航行安全；深度基准面尽管存在离散、非连续的缺点,但其是海道、水运工程测量中海图高程(水深)标定的参考,并为船舶的航行提供安全保障。为此,本文选择深度基准面,用来构建海洋无缝垂直,既具备实际物理意义和应用价值,又符合海洋测绘垂直基准的使用习惯。(2)潮位资料预处理方法研究深度基准面是基于潮位观测资料来确定的,因此潮位观测资料的不准确或缺失都将直接影响深度基准面的确定精度和可靠性。为此,本文在潮汐数据预处理方面开展了如下工作：根据潮位观测资料中影响因素的特征,将其分为：波浪因素引起的观测噪声、潮位观测的缺失和遗漏、粗差和系统误差四大类。①波浪因素的影响提出了一种基于FFT的低通滤波方法,实现了该噪声的有效滤除,给出了截止周期的大小与潮汐分潮周期之间的相关性,认为当截止周期为1h时,基本可彻底消除波浪因素的影响,同时为了防止潮汐中有效成分被滤除,截止周期的大小不要超过3h。②潮位观测的缺失和遗漏根据潮位序列曲线间的相关性参数：潮差比x,潮时差y,基准面偏差z,给出了一种潮位时序中缺失部分的修复方法。90%修复数据的精度优于10cm,80%优于5cm,可满足海道测量规范中潮位修复精度的相关要求。③粗差针对长潮位序列中的粗差问题,提出了一种基于潮汐调和分析模型的粗差修复方法,克服了人工修复方法在效率和精度上的不足,较传统的FFT低通滤波方法,精度有了显著提高,90%修复数据精度优于20cm。④系统误差本文主要研究了由于潮位站验潮“零点”漂移产生的系统误差问题。分别从长潮位序列和短潮位序列两个角度出发,研究了系统误差的消除方法。针对前者,提出了基于概率论中切比雪夫不等式原理的一种新的探测方法,并采用月平均海平面数学期望,对含有系统误差的潮位序列进行修复,精度优于15cm,90%优于10cm；针对后者,提出了一种潮位序列分段匹配探测修复方法,实现了短潮位序列中系统误差有效的探测和修复,精度优于10cm。(3)深度基准面确定精度分析及质量控制深度基准面的高精度确定对建立海洋无缝深度基准面具有重要意义。深度基准面的确定方法大致可分为两类,第一类根据潮汐调和分析所得调和常数按深度基准面模型计算得到；第二类根据深度基准面传递法获得。针对第一类问题,本文着重研究了潮汐调和分析和深度基准面确定的精度、稳定性与潮汐时长之间的相关性,给出了在不同潮汐时长下,适宜采用的分潮模型、个数以及深度基准面的确定精度。针对第二类问题,首先,通过实验分析比较得到最优传递方法,认为最小二乘综合传递法为最优传递法,当同步观测长度≥3天时,传递精度可达5cm。并基于该传递方法,着重研究了深度基准面传递精度与站间潮汐类型值(HK1+HO1)/HM2差值大小的相关性,得如下结论：①在宽阔平缓水域,站间潮汐类型值差值≤0.05,传递距离≤80km时,深度基准面传递精度一般可控制在5cm以内。当传递距离>80km时,深度基准面传递精度逐渐下降,下降速率大概为1cm/km左右。②在狭长湍急水域,站间潮汐类型值差值≤0.05时,传递距离≤40kmm时,深度基准面传递精度一般可控制在15cm以内,当传递距离>40km时,精度迅速下降,已不适合深度基准的传递。③无论是在宽阔还是狭长水域,当潮汐类型值差值>0.05时,由于潮汐性质差异较大,传递精度不甚理想,不建议进行深度基准面的传递。在长江口水域,对上述结论进行了大量的实验分析,验证了其正确性。该结论对日后在长江口水域开展验潮站间深度基准面传递及精度控制具有重要指导意义。(4)海洋无缝垂直基准几何建立方法研究对反距离加权法、最小曲率法、最近邻点法、带线性插值的三角剖分法、多项式回归法、移动曲面拟合法、克里金法和径向基函数法等8种几何建模法进行了深入研究,并借助这些方法分别在温州瓯江和长江口水域构建了局域无缝深度基准面模型。通过对所建立的无缝深度基准面三维曲面的形态特征、深度基准面等值线的分布和变化特征、模型精度等方面进行比较分析后,认为当验潮站数量较多,分布均匀,且深度基准面高变化较为平缓或呈较强规律特征时,几何建模法精度都较高；当验潮站数量较少,分布不均匀,且深度基准面变化无特定规律时,反距离加权法、克里金法和径向基函数法三种方法精度要优于其余几何建模法。此外,该三种方法能较好的反映整体区域深度基准面的变化趋势,所建曲面具有连续光滑等特征,为最优几何建模方法。(5)海洋无缝垂直基准物理建模方法研究针对几何建模方法精度受潮位站分布密度、均匀性和深度基准面的变化复杂程度等因素影响较大的问题,以及几何模型在外推时,精度普遍较低的现象,本文从潮汐传播的物理机制角度出发,提出了基于潮汐调和常数、潮差比以及最小二乘传递参数的三种海洋无缝垂直基准面物理建模方法。通过在长江口以及瓯江区域的多组实验分析,认为三种物理建模方法较几何建模法在精度及稳定性上更具优势。其中基于潮汐调和常数的建模法,无论在外推还是内插时,精度均优于10cm,具有较高的精度和稳定性,为最优的连续无缝深度基准面建模方法。(6)海陆垂直基准转换及精度分析根据参考椭球面、似大地水准面和深度基准面之间的关系,结合各自模型,构建了大地高、正常高和海图高(图载水深)之间的无缝转换模型。同时根据转换模型中各参量的误差来源,给出了每种高程转换模型的误差表达式。更多还原

【Abstract】 In recent years, the implementation of seamless vertical datum is hot issue and not an easy task in marine surveying and mapping area. It is vertical initial benchmark for surveying in ocean, river, and costal zone or at the junction of water and land. Which has such characteristic:a) continuous and seamless; b) dose not vary significantly over time; c) conform to the human habits of marine surveying; d) be apt to convert with other vertical references. The establishment of modernization seamless vertical datum is internal demand of development of marine surveying and the national economic construction, which is inevitable trend, with the growing development and utilization of coastal zone, river shoal, and at the junction of water and land. It provides the theoretical basis and fundamental guarantee for coastline definition, the construction of digital costal areas and the national defense economy.At present, there is still a series of key problems in the establishment of seamless vertical datum. Such as, the choice of vertical datum to establish seamless vertical datum for best, and the pretreatment of the original data before the establishment, and how to establish and convert with other vertical datum etc. Therefore, there are many new ideas, new model and methods having been put forward after summarizing domestic and foreign research status, and careful analysis of existent key problems. Finally, it has realized that seamless vertical datum construction and mutual conversion of different vertical datum. The main work and innovative points reflect in:(1) The choice of vertical reference Firstly analysis and compare the commonly used vertical reference in marine surveying in detail, geoid and reference ellipsoid and mean sea level and depth datum. As land vertical reference, the geoid has continuous and seamless characteristics. But it is a gravity equipotential surface, and apt to be land vertical reference, not suitable as ocean vertical datum. Reference ellipsoid is geometric surface, although has simple mathematical model and continuous, seamless and smooth features, lack of physical significance. Moreover, it dose not accord with human in the habit of surveying and mapping activities. Mean sea level vary with the location and time difference, and can not guarantee the safe navigation. Although depth datum exists discrete, it is the standard vertical reference for chart height in marine surveying and mapping, for the ship security sailing providing protection. Therefore, the paper chooses depth datum to establish marine seamless vertical datum in physical meaning and human use, which both have actual physical significance and application value, and conform with habit of marine surveying and mapping.(2) The tides material pretreatment methodsThe determination of depth datum needs tidal observation, therefore, it is decisive importance to eliminate all kinds of different types of error in tidal observation accurately for precision controlling of depth datum. According to the characteristics of the error, they have been divided into:observation noise cause by the waves, the loss of tidal observation, gross error and system error four categories.a) The influence of waves.The FFT low pass filtering method has been used for filtering the observation noise, and the size of cut-off cycle is related to the cycle of tidal constituent. Through the analysis of the theory and experiment, it has got that the noise can be filtered out when the cut-off cycle is one hours. In order to prevent the active tidal ingredients filtered, the size of cut off cycle should not more than three hours.b) The loss of tidal observationAccording to tidal sequence matching related parameters, ratio of tidal ranges x, time difference of tide y, datum drift z, repair and acquire the missing tidal part. And the repairing can satisfy the90%of repaired point precision within10cm,80%within5cm. thus have already reached the tidal repairing precision standard of specifications for hydrographic survey.c) The gross errorFor the gross error in the long-term tidal observation sequence, this paper has put forward a new filtering method based on the tidal harmonic analysis. The filtering method is better than FFT low pass filtering method in accuracy, and overcome the problem of low accuracy and efficiency of artificial repair. It can satisfy more than90%of repaired point precision within20cm.d) The system errorFor the system error, which is mainly caused by tidal "zero" drift, have been studied. In the long-term and short-term tidal sequence two aspects, the new detection and repairing methods have been put forward respectively. The former detected system error using the chebyshev inequality principle in theory of probability, and repaired them with the mathematical expectation of mean sea, and it can satisfy precision better than15cm and90%of repaired point precision less than10cm. The latter, a self-segmented tidal sequence matching method which is based on the least squares has been put forward. Realize the system error effective detection and repair, the precision less than10cm.(3) The precision analysis and quality control of depth datumThe high accurate determination of depth datum is of great significance to the establishment of marine seamless vertical datum. The determination methods of depth datum can be divided into two classes, the first kind is to use the tidal harmonic constants acquired by tidal harmonic analysis to calculate the depth datum according to the depth datum models. The second type is according to the depth datum transfer methods to obtain. Aim at the first kind, this paper mainly from the relationship research between tidal depth datum stability, precision and number of tidal constituent, length of tidal sequence, has given how to use the number of tidal constituent and harmonic model under the different tidal observation length. For the second, firstly, concludes that the least squares transfer method is best through a large number of experiments of comparing several depth datum transfer methods. When synchronous observation time is more than three days, the transmission precision can reach up to5cm. With this method as an example, this paper put forward the tidal type difference value (HK1+HO1)/HM2between two places as an important transfer basis, and lots of experiments have been researched in the Yangtze estuary region. The conclusion is as follows:a) In a large of flat waters, when tidal type D-value is less than0.05and transmission distance less than80kilometers, the precision of depth datum can be within5cm. Whereas, the transmission distance is more than80km, the precision gradually decline and the decrease rate for about1cm/km or so.b) In the long and narrow rushing waters, when tidal type D-value is less than0.05and transmission distance less than40kilometers, the precision of depth datum can be within15cm. Or when the transmission distance is more than40km, the precision fall rapidly, and it is not suitable for depth datum transfer.c) Whether in a large or long and narrow waters, then tidal type D-value is more than0.05, the transmission precision is not very ideal, not suggestion for the transfer of depth datum. Lots of experiments have been tested in Yangtze estuary river, and it has been proved correct, the above conclusion is important to the precision controlling of depth datum transfer in the Yangtze estuary.(4) Research on the geometric implementation method of marine seamless vertical datumInverse distance weight, minimum curvature method, nearest neighbor interpolation, linear interpolation triangulations method, polynomial regression, moving average method, kriging method and radial basis function method, total eight kinds of commonly used geometric modeling methods, have been respectively used to establish marine seamless vertical datum in the local area of Wenzhou Oujiang river. Through the detailed comparison of the3d surface characteristics, isoline characteristics, outside precision aspects of the established seamless vertical datum, it has got a conclusion as follows:in the case of tidal stations arrangement not intensive and uniform distribution and the complex changes of depth datum height, inverse distance weight, kriging and radial basis function methods are suggested to be adopted to establish marine seamless vertical datum. The three kinds of methods can reflect the change trend of depth datum well, and the built surface has features of continuous and smooth.(5) Research on the physical modeling method of marine seamless vertical datumThe precision of Geometric interpolation method is affected largely by the distribution and number of interpolation node, and elevation changes of depth datum, and when geometric model pushed out, the precision is generally low. From the point of view of tidal physical transmission characteristics, the paper has put forward three kinds of physical interpolation methods which are to use tidal harmonic constant interpolation and the ratio of tidal range interpolation and the least square transfer parameters interpolation to determine depth datum. Through a large of experiments in the Yangzte Estuary River and Oujiang River, it has got that the three physical interpolation methods are more advantages in precision and stability. Among them, the tidal harmonic constant interpolation, whether interpolation or extrapolation, the precision can be in less than10cm, and has very high accuracy and stability, and is the best method to establish seamless vertical datum.(6) Transformation between land and ocean vertical reference and precision controlAccording to the relationship among reference ellipsoid, geoid and depth datum, the specific conversion models have been put forward among geodetic height and normal height and chart height. At the same time, detailed analyzing of error source of each parameter in the transformation model has been made, and has given error expression of elevation transformation model.更多还原