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1.
An idealized numerical model is developed to study the spatial asymmetry of ebb–tidal deltas under influence of large-scale alongshore tidal currents. It is shown that the asymmetry of the delta depends on the magnitude of the cross-shore and large scale alongshore tidal currents, their phase difference, and on the width of the inlet. Model results are compared with observations of ebb–tidal deltas of the tidal inlet systems of the Dutch Wadden Sea and with the ebb–tidal delta of the Eastern Scheldt, located in the southwestern part of the Netherlands. The modeled current and residual sediment transport patterns agree well with observed ones. The modeled asymmetry of the ebb–tidal delta also agree with observed ones. Furthermore, bottom patterns are consistent with those found with a previous version of the idealized model which focused on the modeling of symmetric ebb–tidal deltas. However, the model is not able to reproduce the observed ebb-dominated channel. The underlying physical processes are explained in terms of vorticity dynamics. The convergence of the mean vorticity flux generates mean vorticity and thereby residual circulation. An analysis shows there is competition between two contributions to the convergence of the mean vorticity flux. This competition explains the sensitivity of the results to the model parameters. 相似文献
2.
《地震学报(英文版)》1998,(4)
ＦｒｅｑｕｅｎｃｙｒｅｓｐｏｎｓｅｏｆｔｉｌｔｍｅｔｅｒｓａｎｄｔｉｄａｌｆａｃｔｏｒＪＵＮＹＡＮＧ（杨军）ＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕｏｆＪｉａｎｇｓｕＰｒｏｖｉｎｃｅ,Ｎａｎｊｉｎｇ２１００１４．ＣｈｉｎａＡｂｓｔｒａｃｔＴｈｅｒｅｌａ... 相似文献
3.
《地震学报(英文版)》1998,(4)
ＴｈｅｓｕｒｆａｃｅｓｐｈｅｒｉｃａｌｈａｒｍｏｎｉｃｓａｎｄｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｉｄａｌｇｅｎｅｒａｔｉｎｇｐｏｔｅｎｔｉａｌＱＩＮ－ＷＥＮＸＩ（郗钦文）ＣｅｎｔｅｒｆｏｒＡｎａｌｙｓｉｓａｎｄＰｒｅｄｉｃｔｉｏｎ,ＣｈｉｎａＳｅｉｓ... 相似文献
4.
The synthetic tidal parameters with high spatial resolution for gravity over China and its neighbor area are con- structed with Earth’s tidal model and ocean tide loading calculated using TPXO7 global ocean tide model as well as tidal data over China seas. The comparison between synthetic parameters and ones observed by spring gravime- ters at some seismic network stations and Hong Kong station and one observed by super-conducting gravimeter at Wuhan station shows that the average differences in amplitude factors and phases are smaller than 0.005 and 0.5° respectively; and that the discrepancies between observational and synthetic parameters are dependent on gravim- etric technique in that the synthetic parameters are in well agreement with the superconducting gravimetric obser- vations. This also indicates that the synthetic result is a good estimation for tidal gravity, and the numerical results in the present paper not only can provide ground and space gravimetry such as absolute gravimetry with correction model of tidal gravity, but also provide effective tidal parameters over areas where no observation is carried out. 相似文献
5.
The comparative observations of the tidal gravity in Three Gorges reservoir area, recorded with the LCR-ET20 gravimeter from Institute of Geodesy and Geophysics, Chinese Academy of Sciences and the DZW-9 gravimeter from Institute of Seismology, China Earthquake Administration, are introduced. High-accuracy tidal gravity pa-rameters in this area are obtained, and the scale factor of the DZW-9 gravimeter is also estimated at a value of ?(756.06±0.05)×10?8 m?s?2V?1. The observed residuals of the corresponding instruments are investigated. Nu-merical results indicate that the long-term drift of the DZW-9 gravimeter appears a linear characteristic, and the observed accuracy is of the same order comparing with that of the LCR-ET20 gravimeter. The results given in the paper can provide with an effective reference model of the tidal gravity correction to the ground based and space geodesy. 相似文献
6.
Surface elevation and current records contain non-tidal variance, often dismissed as noise. The processes responsible for the non-tidal component may also modulate the tidal signal, altering its strength and frequency structure. Because of their manner of generation and propagation, internal tides are inherently irregular. The non-stationary character of these and other tidal processes provides an integral and useful property of tidal records, because it provides an opportunity to obtain insights into tidal dynamics and the interaction of tidal and non-tidal processes. It is, moreover, productive to use multiple approaches in analyzing coastal and estuarine tidal processes so that both the time-varying and average frequency content are determined. Only by confronting the causes of non-stationary behaviour in this way can some of the remaining challenges in tidal analysis and prediction be overcome, e.g. shelf and estuarine currents, river tides, internal tides, tide-surge interactions and tidally influenced ecological processes. Several examples illustrate the utility of non-stationary tidal analysis methods.Responsible Editor: Jens Kappenberg 相似文献
7.
From July 2003 to July 2004, samples were collected on Chongming Island east tidal flat every two months. The research showed that the nitrous oxide (N2O) production rate was very low in the water, Chongming east tidal flat (CM) sediment was the N2O source of the water. Sediment N2O natural production rate was between -0.08 and 1.74 μmolN·m-2·h-1. N2O natural production rate was higher in the summer. The difference of the N2O natural production rate in the different tidal flats, the correlation between the N2O natural production rate and the denitrification rate, and those with the temperature and DO indicate that middle tidal flat sediment denitrification was the main process of the N2O production, while in the low tidal flat sediment, the production of the N2O came from several processes of the nitrogen cycling. Tidal flat sediment denitrification reaction was stronger in summer and winter but relatively lower in the late autumn and early spring. Seasonal change of the sediment denitrification rate was wide, from 1.12 to 33.34 μmolN·m-2·h-1. Temperature, DO and the coactions of them had the prominent effect on the tidal flat sediment denitrification. 相似文献
8.
Research on distinguishing method and mechanism of tidal deformation anomalies before large earthquakes 总被引：1，自引：0，他引：1
Introduction There are many researches on modulating and triggering seismic activities by tidal force in China and abroad. Heaton (1975) studied the tidal triggering of seismic activity and discovered that the tidal stress did have an obvious triggering action on the dip-slip or oblique slip great earthquakes. Tidal triggering of earthquakes has been studied for a long time in China, especially in recent years. For example, LI et al (2001) provided the relationship between the solar and luna… 相似文献
9.
Study on tidal gravity observations obtained at stations Zhongshan and Changcheng, Antarctic 总被引：1，自引：0，他引：1
Lü Chun-cao 《地震学报(英文版)》2001,14(3):325-332
IntroductionThe purpose of the studies on the tidal gravity observations on the Earth(s surface is to investigate the properties of the deformation and the tidal gravity variations of the Earth under the action of the luni-solar tidal force. These variations relate to the internal structure, shape and the medium(s rheology properties of the Earth (Wahr, 1981; Dehant, 1987). The theoretical studies and observations indicated that the amplitudes and the tidal parameters, including the amplitud… 相似文献
10.
O. Yu. Vinogradova 《Izvestiya Physics of the Solid Earth》2012,48(7-8):572-586
The load Love numbers, Green’s functions, and oceanic tidal loading effect over the territory of Europe are calculated for the PREM and IASP91 models of the Earth and CSR3 ocean-tide model. Computations were carried out for the reference periods of 1 s, 12 h, and 24 h. It is established that the corrections to gravity acceleration for the M2 wave significantly differ in different models. 相似文献
11.
Czizeweski Anthea Pimenta Felipe Mendonça Saavedra Osvaldo Ronald 《Ocean Dynamics》2020,70(5):667-682
Ocean Dynamics - Marine resources are outstanding among renewable energy for their wide occurrence and diverse possibilities of exploitation. The tidal resource can be harnessed by the use of both... 相似文献
12.
Accurate determination of calibration factor for tidal gravity observation of a GWR-superconducting gravimeter 总被引：4，自引：0，他引：4
Introduction The superconducting gravimeters (SGs) are widely used to observe the change in temporal and spatial gravity field by many countries along the world, considering their characteristics as of the high-precision, good continuity and stability. By using the temporal variation of the tidal grav-ity obtained from the global network of SGs, the Global Geophysics Project (GGP) aims at some hot problems in geophysics and geodynamics (SUN, HSU, 1997). The original observations of the c… 相似文献
13.
Introduction The tidal variation signals of the solid Earth recorded with the modern measuring techniques can be used to provide effectively the means to cognize the Earths motion, deformation and structure character, especially to monitor the material motion in the Earths interior. In the recent 20 years, the distribution character of the global gravity field has made great progress since the continuous and deep theoretical studies in geophysics and geodesy domains. The successful manufactur… 相似文献
14.
The Earth＇s free core nutation （FCN） is a retrograde eigenrnode which is attributed to the interaction between the solid mantle and the liquid core of the rotational elliptical Earth. This mode appears as an eigenmode of nearly diurnal free wobble （NDFW） in a terrestrial reference frame with a period of about one day （XU et al, 2001）. Therefore, the NDFW will lead to an obvious resonance enhancement in the diurnal tidal gravity observations, especially those of the tidal waves with frequencies closed to its eigenfrequency such as P1, K1, ψ1 and Ф1. The FCN resonance parameters can be retrieved accurately by high-precision tidal gravity observations, especially those recorded with the superconducting gravimeters （SG）. The Global Geodynamics Project （GGP） organized by IUGG took it as an important content for determining the FCN resonance parameters by using gravity data. However, the results are affected by many factors such as station location, background noise, the selection of the tide-generating potential tables, ocean tide models, data processing techniques and so on. In our study, the FCN parameters will be retrieved by using the SG observations at Wuhan, and the effects of the choices of various tide-generating potential tables, oceanic models and weight functions on the estimation of the FCN parameters will be discussed in detail, 相似文献
15.
The Earth’s free core nutation (FCN) is a retrograde eigenmode which is attributed to the interaction between the solid mantle and the liquid core of the rotational elliptical Earth. 相似文献
16.
《Journal of Atmospheric and Solar》2008,70(16):2005-2013
Based on the horizontal winds measured using SKiYMET meteor wind radar during the period of June 2004–May 2007, the seasonal and interannual variability of the diurnal and semidiurnal amplitudes and phases in the mesospheric and lower thermospheric (MLT) region over a low-latitude station Trivandrum (8.5°N) are investigated. The monthly values of amplitudes and phases are calculated using a composite day analysis. The zonal and meridional diurnal tidal amplitudes exhibit both annual and semiannual oscillations. The zonal and meridional components of semidiurnal tide show a significant annual oscillation. The phase values of both diurnal and semidiurnal tides exhibit annual oscillation above 90 km. The effect of background wind in the lower atmosphere on the strength of diurnal tidal amplitudes in the MLT region is studied. The effect of diurnal tides on the background wind in the lower thermosphere is also discussed. 相似文献
17.
Natural tidal channels often need deepening for navigation purposes (larger vessels). The depth increase may lead to tidal amplification, salt intrusion over longer distances, and increasing sand and mud import. Increasing fine sediment import, in turn, may start a process in which the sediment concentration progressively increases until the river becomes hyper-turbid, which may lead to increased dredging volumes and to decreased ecological values. These effects can be modeled and studied using detailed 3D models. Reliable simplified models for a first quick engineering evaluation are however lacking. In this paper, we apply both simplified and detailed 3D models to analyze the effects of channel deepening in prismatic and weakly converging tidal channels with saturated mud flow. The objective is to gain quantitative understanding of the effects of channel deepening on mud transport. We developed a simplified tidal mud model describing most relevant processes and effects in saturated mud flows with only minor horizontal transport gradients (quasi uniform conditions). The simplified model is not valid for non-saturated mud flow conditions. This model can either be used in standalone mode or in post-processing mode with computed near-bed velocities from a 3D hydrodynamic model as an input. The standalone model has been compared to various field data sets. Mud transport processes in the mouth region of muddy tidal channels can be realistically represented by the simplified model, if sufficient salinity and sediment data are available for calibration. The simulation of tidal mud transport and the behavior of an estuarine turbidity maximum (ETM) in saturated and non-saturated mud flow conditions cannot be represented by the simplified model and requires the application of a detailed 3D model. 相似文献
18.
Natural tidal channels often need deepening for navigation purposes (to facilitate larger vessels). Deepening often leads to tidal amplification, salinity intrusion, and increasing sand and mud import. These effects can be modelled and studied by using detailed 3D models. Reliable simplified models for a first quick evaluation are however lacking. This paper presents a simplified model for sand transport in prismatic and converging tidal channels. The simplified model is a local model neglecting horizontal sand transport gradients. The latter can be included by coupling (as post-processing) the simplified model to a 2DH or 3D flow model. Basic sand transport processes in stratified tidal flow are studied based on the typical example of the tidal Rotterdam Waterway in The Netherlands. The objective is to gain quantitative understanding of the effects of channel deepening on tidal penetration, salinity intrusion, tidal asymmetry, residual density-driven flow, and the net tide-integrated sand transport. We firstly study the most relevant tidal parameters at the mouth and along the channel with simple linear tidal models and numerical 2DH and 3D tidal models. We then present a simplified model describing the transport of sand (TSAND) in tidal channels. The TSAND model can be used to compute the variation of the depth-integrated suspended sand transport and total sand transport (incl. bed-load transport) over the tidal cycle. The model can either be used in stand-alone mode or with computed near-bed velocities from a 3D hydrodynamic model as input data. 相似文献
19.
Chen Peixiong Sun Zhilin Zhou Xin Xia Yuezhang Li Li He Zhiguo Wang Rusheng Xie Haijian 《Ocean Dynamics》2021,71(3):323-341
Ocean Dynamics - Coastal reclamation projects have been extensively constructed along the coastline of the East China Sea over the past decades. To investigate the impact of reclamations on the... 相似文献
20.
R. Almar B. Castelle B.G. Ruessink N. Sénéchal P. Bonneton V. Marieu 《Continental Shelf Research》2010
Five weeks of hourly, 10-min time-exposure video images were used to analyze the meso–macro-tidal double-barred Truc Vert Beach, SW France, under intense wave forcing. The four storms experienced, one of which with an offshore significant wave height over 8 m, induced dramatic changes in the double sandbar system. The subtidal outer bar migrated offshore rapidly (up to 30–50 m/day) and its pre-existing crescentic pattern was wiped out. The seaward-protruding parts of the outer bar barely migrated offshore during the most intense storm, whereas a landward-protruding part was shed off. Over the entire study period, the outer-bar dynamics was dominated by alongshore-averaged changes rather than alongshore non-uniform changes, while the opposite was observed for the inner bar. In addition, the outer-bar dynamics was predominantly controlled by the time-varying offshore wave conditions, whereas the inner-bar dynamics was influenced largely by the tide-range variations. Our observations put forward the key role of morphological settings (the presence of a subtidal bar and its shape) and tidal range in governing inner-bar behaviour within a double sandbar dynamics, and provide strong support for previous suggestions that sandbars cannot be studied in isolation. 相似文献