Comparison of predictions of a numerical model and observations of tides in Bass Strait

1985 ◽  
Vol 36 (6) ◽  
pp. 737 ◽  
Author(s):  
CB Fandry ◽  
GD Hubbert ◽  
PC McIntosh
Keyword(s):  
Numerical Model ◽  
Sea Level ◽  
Travelling Waves ◽  
Phase Lag ◽  
Tidal Amplitude ◽  
Tidal Constituent ◽  
Tidal Waves ◽  
Level Data ◽  
Grid Points ◽  
Tidal Constituents

A depth-averaged numerical model is used to describe the tidal regime in Bass Strait. Tidal constants corresponding to the four major tidal constituents (M2, S2, O1 and K1) are calculated at the grid points of the model, and co-amplitude and co-phase contours drawn for each of the constituents. At 17 locations in Bass Strait, the computed tidal constants are in excellent agreement with those obtained from flow and sea-level data. The dominant tidal constituent is found to be the semi-diurnal, M2, tide, which is predicted by the model with an accuracy of 10% in sea-level amplitude and 10� in phase. The M2 tide in Bass Strait is generated by two oppositely travelling waves, one entering the eastern end and another entering the western end with a phase lag of about 3 h. Some amplification of these waves occurs as they move from the deep water into the much shallower continental shelf waters of the Strait, and their superposition causes a large tidal amplitude (up to 1.2 m) to occur in central Bass Strait. The other three constituents are much weaker than the M2 constituent, and are driven by tidal waves entering from the western end. They propagate eastwards, emerging at the eastern end with little change in amplitude throughout the Strait.

scholarly journals Model Based Assessment of the Reflection Behavior of Tidal Waves at Bathymetric Changes in Estuaries

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 489
Author(s):  
Vanessa Sohrt ◽  
Sebastian S.V. Hein ◽  
Edgar Nehlsen ◽  
Thomas Strotmann ◽  
Peter Fröhle
Keyword(s):  
Cross Sectional ◽  
High Agreement ◽  
Tidal Waves ◽  
Level Data ◽  
Water Level Data ◽  
Abrupt Changes ◽  
Water Effects ◽  
Potential Impact ◽  
Tidal Constituents ◽  
Harmonic Components

Estuaries are often modified by human activities. Adjustments in the morphology of an estuary have a potential impact on the hydrodynamics and on the reflection behavior of the tide. The influence of such system changes on the complex tidal regime with a large number of superimposed tidal constituents is not fully understood yet. The reflection properties of estuaries that are characterized by abrupt changes in geometry are systematically investigated on the basis of simplified estuary model approaches to improve the understanding of the oscillation and reflection behavior of tidal waves in estuaries. The reflection coefficients at abrupt cross-sectional changes are determined by two different methods, i.e., an analytical energy-based approach and a hydrodynamic numerical (HN) model. Comparisons indicate a high agreement of the results of the different methods when evaluating the reflection coefficient. The tidal constituents are reflected at partial and total reflectors and amplified by shoaling depending on the water depths, the height of the bottom step and the horizontal constriction. A harmonic analysis of simulated water level data partly shows the formation and amplification of higher harmonic components as a result of shallow water effects. The interaction with reflectors results in an increasing amplification of the tidal constituents and the tide.

scholarly journals Seasonal variation of the principal tidal constituents in the Bohai Sea

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Daosheng Wang ◽  
Haidong Pan ◽  
Guangzhen Jin ◽  
Xianqing Lv
Keyword(s):  
Seasonal Variation ◽  
Harmonic Analysis ◽  
Sea Level ◽  
Seasonal Variations ◽  
Eddy Viscosity ◽  
Bohai Sea ◽  
Phase Lag ◽  
Vertical Eddy Viscosity ◽  
Tidal Constituents ◽  
Vertical Eddy

Abstract. The seasonal variation of tides plays a significant role in water level changes in coastal regions. In this study, seasonal variations of four principal tidal constituents, M2, S2, K1, and O1, in the Bohai Sea, China, were studied by applying an enhanced harmonic analysis method to two time series: 1-year sea level observations at a mooring station (named E2) located in the western Bohai Sea and 17-year sea level observations at Dalian. At E2, the M2 amplitude and phase lag have annual frequencies, with large values in summer and small values in winter, while the frequencies of S2 and K1 amplitudes are also nearly annual. In contrast, the O1 amplitude increases constantly from winter to autumn. The maxima of phase lags appear twice in 1 year for S2, K1, and O1, taking place near winter and summer. The seasonal variation trends estimated by the enhanced harmonic analysis at Dalian are different from those at E2, except for the M2 phase lag. The M2 and S2 amplitudes show semi-annual and annual cycles, respectively, which are relatively significant at Dalian. The results of numerical experiments indicate that the seasonality of vertical eddy viscosity induces seasonal variations of the principal tidal constituents at E2. However, the tested mechanisms, including seasonally varying stratification, vertical eddy viscosity, and mean sea level, do not adequately explain the observed seasonal variations of tidal constituents at Dalian.

scholarly journals Frictional interactions between tidal constituents in tide-dominated estuaries

Ocean Science ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 769-782 ◽  
Author(s):  
Huayang Cai ◽  
Marco Toffolon ◽  
Hubert H. G. Savenije ◽  
Qingshu Yang ◽  
Erwan Garel
Keyword(s):  
Iterative Procedure ◽  
Underlying Mechanism ◽  
Hydrodynamic Equations ◽  
Tidal Amplitude ◽  
Tidal Constituent ◽  
Friction Term ◽  
Southern Portugal ◽  
Tidal Constituents ◽  
Alluvial Estuaries ◽  
Effective Friction

Abstract. When different tidal constituents propagate along an estuary, they interact because of the presence of nonlinear terms in the hydrodynamic equations. In particular, due to the quadratic velocity in the friction term, the effective friction experienced by both the predominant and the minor tidal constituents is enhanced. We explore the underlying mechanism with a simple conceptual model by utilizing Chebyshev polynomials, enabling the effect of the velocities of the tidal constituents to be summed in the friction term and, hence, the linearized hydrodynamic equations to be solved analytically in a closed form. An analytical model is adopted for each single tidal constituent with a correction factor to adjust the linearized friction term, accounting for the mutual interactions between the different tidal constituents by means of an iterative procedure. The proposed method is applied to the Guadiana (southern Portugal–Spain border) and Guadalquivir (Spain) estuaries for different tidal constituents (M2, S2, N2, O1, K1) imposed independently at the estuary mouth. The analytical results appear to agree very well with the observed tidal amplitudes and phases of the different tidal constituents. The proposed method could be applicable to other alluvial estuaries with a small tidal amplitude-to-depth ratio and negligible river discharge.

scholarly journals Surface currents in the Porsanger fjord in northern Norway

2016 ◽  
Vol 37 (3) ◽  
pp. 337-360 ◽  
Author(s):  
Malgorzata Stramska ◽  
Andrzej Jankowski ◽  
Agata Cieszyńska
Keyword(s):  
Sea Level ◽  
Barents Sea ◽  
Surface Current ◽  
Current Data ◽  
Tidal Range ◽  
Surface Currents ◽  
Tidal Component ◽  
Level Data ◽  
Sea Level Oscillations ◽  
Tidal Constituents

Abstract We describe surface currents in the Porsanger fjord (Porsangerfjorden) located in the European Arctic in the vicinity of the Barents Sea. Our analysis is based on surface current data collected in the summer of 2014 using High Frequency (WERA, Helzel Messtechnik GmbH) radar system. One of our objectives was to separate out the tidal from the nontidal components of the currents and to determine the most important tidal constituents. Tides in the Porsanger fjord are substantial, with tidal range on the order of about 3 m. Tidal analysis attributes to tides about 99% of variance in sea level time series recorded in Honningsvaag. The most important tidal component in sea level data is the M2 component, with amplitude of ~90 cm. The S2 and N2 constituents (amplitude of ~20 cm) also play a significant role in the semidiurnal sea level oscillations. The most important diurnal component is K1 with amplitude of about 8 cm. The most important tidal component in analyzed surface currents records is the M2 component. The second most important component is the S2. Our results indicate that in contrast to sea level, only about 10-30% of variance in surface currents can be attributed to tidal currents. This means that about 70-90% of variance is due to wind-induced and geostrophic currents.

scholarly journals Tides in the southern area of the Kara Sea in the vicinity of the Belyi island

2020 ◽  
Vol 66 (1) ◽  
pp. 6-19
Author(s):  
G. N. Voinov ◽  
O. A. Morozova ◽  
A. V. Nesterov ◽  
K. A. Kornishin ◽  
Ya. O. Yefimov
Keyword(s):  
Seasonal Variation ◽  
Sea Level ◽  
Kara Sea ◽  
Method Of Least Squares ◽  
Tidal Waves ◽  
Competing Interests ◽  
Level Data ◽  
Independent Series ◽  
Hydrocarbon Deposits ◽  
First Time

A number of promising hydrocarbon deposits are known in the south-western part of the Kara Sea. A safe development of these deposits requires hydrometeorological support, including sea-level observations. The paper deals with sea-level data of autonomous anchored buoy station. The period of observation is about 2 years, and the observation dataset is divided into 2 periods due to the displacement of the buoy station. The coordinates of the first position of the buoy station are known but they had been changed after the displacement (possibly due to the action of the ice ridge keels).Data from two time series of observations are studied by harmonic analysis, using the method of least squares by AARI version. According to the average monthly and mean annual values of the main tides it is found that the data includes two independent series. It is determined that the second series may be considered uniform. In order to locate of the anchored buoy station we calculated new coordinates using the empirical tidal charts of the M2 wave.As a result, the harmonic constants of the eight main tidal waves for the Belyi Island area are presented for the first time. The new data confirms the amphidromic system in tides O1 and Q1 , between the Zhelaniya Cape and the Belyi Island. According to the new data the maximum seasonal variation in the range of M2 tide was observed in June, and the minimum of the phase angle was observed in July. This unusual seasonal variation of the M2 tide corresponds to previous observations data from the Uedinenia Island.The authors have no competing interests.

scholarly journals Remote wind stress influence on mean sea level in a subtropical coastal region

2012 ◽  
Vol 60 (3) ◽  
pp. 331-342
Author(s):  
Mabel Calim Costa ◽  
Marcos Eduardo Cordeiro Bernardes
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Stress Component ◽  
Coastal Region ◽  
Phase Lag ◽  
Mean Sea Level ◽  
Low Pass ◽  
Grid Points ◽  
The Relationship ◽  
Stress Influence

The purpose of this study was to assess the relative influence of remote wind stress on mean sea level (MSL) variations in the coastal region of Cananeia (Sao Paulo State, Southern Brazil) during the period from 1/1/1955 to 12/31/1993. An optimized low-pass Thompson filter for the study area, and spectral analysis (cross spectrum, coherence and phase lag) of the relationship between the MSL and both parallel (T//) and perpendicular (T|) wind stress components were applied. These were extracted from four grid points of the NCEP/NCAR global model. The predominance of annual oscillations as those of greatest coherence and energy, of periods of approximately 341 days (frequency of 0.00293 cpd) and 410 days (frequency of 0.00244 cpd), respectively, were observed. Offshore NCEP/NCAR grid points were those with the highest coherence and energy throughout the study in relation to the observed MSL. This may be linked to the restriction of the NCEP/NCAR model as regards the inland limit. It is also concluded that remote wind stress may play an important role in several MSL time scales, including the annual ones. Based on criteria such as coherence and energy peaks, the wind stress component of greatest effect on MSL was the parallel one.

scholarly journals Spectral Analysis of Satellite Altimeter and Tide Gauge Data around the Northern Australian Coast

2020 ◽  
Vol 12 (1) ◽  
pp. 161 ◽  
Author(s):  
Zahra Gharineiat ◽  
Xiaoli Deng
Keyword(s):  
Time Series ◽  
Sea Level ◽  
High Frequency ◽  
Tide Gauge ◽  
Tidal Range ◽  
Tide Gauges ◽  
The North ◽  
Power Spectral ◽  
Level Data ◽  
Tidal Constituents

The north of Australia is known for its complex tidal system, where the highest astronomical tides (HATs) reach 12 m. This paper investigates the tidal behaviour in this region by developing spectral climatology for tide gauge and altimetry data. Power spectral density analysis is applied to detect the magnitude of ocean tides in 20 years of sea-level data from multimission satellite altimeters and tide gauges. The spectra of altimetry sea level anomaly (SLA) time series have their strongest peaks centred at approximately 2.11, 5.88, and 7.99 cycles per year (cpy), corresponding to the diurnal and semidiurnal tidal constituents K1, M2, and O1, respectively. Closer to the coastline, the spectra peak at high-frequency overtide and shallow-water constituents such as M4, MK4, and MK3. There have been many large, high-frequency spectral peaks near the coastline, indicating the difficulty of predicting tidal signals by coastal altimetry. Similar to altimetry observations, there are dominant semidiurnal and diurnal tidal peaks in tide gauge SLA time series accompanying a number of overtides. The semidiurnal and diurnal peaks are mostly higher on the northwest coast of Australia compared with the north and northeast coast. The results from both altimetry and tide gauges indicate that tidal range increases with increasing continental shelf.

Evaluation of a numerical model of the British-Irish ice sheet using relative sea-level data: implications for the interpretation of trimline observations

2012 ◽  
Vol 27 (6) ◽  
pp. 597-605 ◽  
Author(s):  
Joseph Kuchar ◽  
Glenn Milne ◽  
Alun Hubbard ◽  
Henry Patton ◽  
Sarah Bradley ◽  
...  
Keyword(s):  
Numerical Model ◽  
Sea Level ◽  
Ice Sheet ◽  
Relative Sea Level ◽  
Level Data

PREDICTING TIDAL MARSH SURVIVAL OR SUBMERGENCE TO FUTURE SEA-LEVEL RISE USING PALEO SEA-LEVEL DATA

2018 ◽  
Author(s):  
Benjamin P. Horton ◽  
◽  
Ian Shennan ◽  
Sarah L. Bradley ◽  
Niamh Cahill ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tidal Marsh ◽  
Level Data
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