共查询到19条相似文献，搜索用时 109 毫秒
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面对近年海图测量逐渐由近海向外延伸的发展现状,其对水位改正的要求越来越高,水位改正是海图测量中的一个尤为重要的技术环节,对保证测量精度起着极其重要作用。实际测量作业中,在一些潮汐性质变化复杂的海域,采用传统水位改正方法面临设站数量多、难度大、易丢失、精度难保证等难点。针对测区潮波分布的复杂性与特殊性,基于POM模式,采用"混合"同化法同化由T/P卫星测高数据反演的沿迹潮汐参数构建了高分辨率高精度的潮汐模型,利用余水位的空间相关性,称之为基于潮汐模型与余水位监控的水位改正法。通过海图测量实例中基于潮汐模型与余水位监控法的应用,对测量成果精度进行了分析和验证,为海图测量在水位改正方法的选择提供了技术支持,进而对保证测量精度有着重要的现实意义。 相似文献
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本文介绍一种简易的水位改正方法，减少了传统的水位改正方法中的计算工作量，可提高工效５０×１０－２；其精度相当于传统的逐点计算水位改正方法的精度。 相似文献
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水位在忽略观测误差的前提下,可分解为潮位和余水位,后者具有较强的空间相关性以及非平稳特征,是影响水位预报精度的主要因素。港口工程、航运计划编制等方面对实时高精度水位预报具有重要需求,这对余水位预报模型构建提出了更高要求。另外,利用高精度余水位预报模型可减少验潮站布设数量。针对余水位短期预测模型精度不高的现状,本文对余水位进行集合经验模态(EEMD)分解,获得余水位在时间序列上的本征模函数(IMF);使用快速傅立叶变换(FFT)分析各本征模函数的频谱特征;再利用BP神经网络对各个本征模函数进行训练,预测了未来6 h、12 h、24 h的余水位值。对哥伦比亚河下游河口处的3组典型验潮站的余水位数据的预测结果表明,在未来6 h、12 h内的余水位的预测精度达到厘米级,在24 h内接近厘米级,证明了该组合模型在余水位短期预测方面的可行性。 相似文献
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Numerical Simulation of Residual Circulation due to Bottom Roughness Variability Under Tidal Flows in A Semi-Enclosed Bay 总被引：7，自引：0，他引：7
1 .IntroductionWater pollution has a large influence on water environment and our life ;for example ,it some-times induces oxygen depression,blue tide andredtide in a bay.For water purificationin a semi-en-closed sea ,some new methods to activate the tidal exchange between an inner bay and an outer seaarea by control of a tidal residual current have been proposed (Awayaet al .,1995) . Huthnance(1973) ,Zimmerman (1978 ,1981) , Loder (1980) ,and Robinson (1983) considered cases wherethe fricti… 相似文献
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基于长江口外鸡骨礁、绿华山潮位站多年实测潮汐资料,开展潮汐调和分析与应用研究。采用最小二乘法计算调和常数,研究不同分潮组合及不同资料长度对调和分析结果的影响。采用规范法及直接预报法计算深度基准面,并分析计算结果。采用余水位订正方法推算潮位,并进行精度验证。结果表明:调和分析精度随分潮个数的增加而提高;采用年实测潮汐资料调和分析的精度总体高于采用多年实测潮汐资料调和分析的精度;采用预报年份相邻的年实测潮汐资料进行潮汐预报精度较高;理论最低潮面计算值,规范法较直接预报法偏小。基于绿华山站与鸡骨礁站实测资料进行余水位推算验证,精度基本满足实用要求。 相似文献
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A two-dimensional hydrodynamic model was set up and validated for the west coast of India. The spatio-temporal variation of the tidal constituents for a 110 km stretch of the southwest coast of India was then studied by setting up a fine grid model. The study brings out variability in the shallow water constituents and their selective amplification. Within the Cochin estuary, the amplitudes of almost all the major tidal constituents show a gradual reduction upstream compared to other locations. The shallow water constituents show significant amplification and Z0, the constituent related to mean sea level shows five-fold amplification within the estuary. 相似文献
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R. K. Nayak M. Salim S. K. Sasamal P. C. Mohanthy R. K. Bharadwaj K. H. Rao 《Marine Geodesy》2016,39(5):331-347
The present tidal correction of sea level records of Satellite with ARgoes and ALtimeter (SARAL) is based on the finite element solution (FES) of global tide model FES2012 tidal solution. In this study, we examined the validity of the tidal corrections in the coastal oceans around India using tide gauge measurements and a regional tidal model. Our regional model is based on the barotropic version of the Princeton Ocean Model that is forced by the time-varying tidal levels at the open ocean end based on the global FES99 tidal solution. Tide charts prepared from the simulated tidal levels are very similar to the FES tidal solutions. Comparison with the tide gauge measurement shows close agreement with the regional tidal solutions. On the other hand, the agreement with the FES tide models differ significantly in the Gulf of Khambhat and the Gulf of Kutch on the northwest, and in the Hooghly estuary on the northeast continental shelf. However, the agreement is exceptional in other parts of the study domain. These tidal solutions are used in the SARAL-ALTIKA X-track data to assess the FES tidal correction and to draw some inferences associated with the coastal processes. It is revealed that these corrections are reasonably accurate for the coastal oceans around India except the aforementioned converging channels. 相似文献
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Accurate water levels modeling and prediction is essential for safety of coastal navigation and other maritime applications. Water levels modeling and prediction is traditionally developed using the least-squares-based harmonic analysis method that estimates the harmonic constituents from the measured water levels. If long water level measurements are not obtained from the tide gauge, accurate water levels prediction cannot be estimated. To overcome the above limitations, the current state-of-the-art artificial neural network has recently been developed for water levels prediction from short water level measurements. However, a highly nonlinear and efficient wavelet network model is proposed and developed in this paper for water levels modeling and prediction using short water level measurements. Water level measurements (about one month and a week) from six different tide gauges are employed to develop the proposed model and investigate the atmospheric changes effect. It is shown that the majority of error values, the differences between water level measurements and the modeled and predicted values, fall within the −5 cm and +5 cm range and root-mean-squared (RMS) errors fall within 1–6 cm range. A comparison between the developed highly nonlinear wavelet network model and the harmonic analysis method and the artificial neural networks shows that the RMS of the developed wavelet network model when compared with the RMS of the harmonic analysis method is reduced by about 70% and when compared with the RMS of the artificial neural networks is reduced by about 22%. It is also worth noting that if the atmospheric changes effect (meteorological effect) of the air pressure, the air temperature, the relative humidity, wind speed and wind direction are considered, the performance accuracy of the developed wavelet network model is improved by about 20% (based on the estimated RMS values). 相似文献