The M4 Shallow Water Tidal Constituent From Altimetry and Tide Gauges

2003 ◽  
pp. 231-235
Author(s):  
Ole B. Andersen
Keyword(s):  
Shallow Water ◽  
Tide Gauges ◽  
Tidal Constituent

scholarly journals STUDY COMPONENTS OF SHALLOW WATER TIDE (OVER AND COMPOUND TIDES) 1 DIMENSIONAL CHANNEL MODEL BY USING VARIATIONAL DATA ASSIMILATION METHOD

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Evie H. Sudjono ◽  
A. Setiawan ◽  
S. Hadi ◽  
N. S. Ningsih
Keyword(s):  
Data Assimilation ◽  
Harmonic Analysis ◽  
Shallow Water ◽  
Root Mean Square ◽  
Channel Model ◽  
Variational Data Assimilation ◽  
Mean Square ◽  
Tidal Constituent ◽  
Sea Transportation ◽  
Improve Accuracy

<p>Shallow water tides are very important to improve accuracy of tidal predictions. It is used by port interest, sea transportation, fishing industry, coastal engineering, etc. Simulation of shallow water tides was obtained from harmonic analysis of 1 dimensional channel model (12 grid) by using variational data assimilation (grid 3 and 8). Two partial tides with angular frequencies σ1 = 1,4x10-4 and σ2 = 1,6x10-4 rad/sec and amplitude A1 = 1x10-8 and A2 = 0,5x10-8 meters are used for defining external forcing in the model domain. When inspecting the amplitudes of both partial tides σ1 and σ2 and some of their dominant over- and compound tides (σ3 = 2σ1-σ2 and σ4 = 3σ1), in general the “to be corrected” solution can be improved significantly. Root mean square (rms) error of tidal constituent σ1 between the “reference” and the “to be corrected” without data assimilation is 0,1075 m/sec, and for σ2 is 0,0440 m/sec, respectively. On the other hand, the harmonic analysis of the phase of tidal constituent σ1 showed a good result (root mean square = 0.0000 m/s) and for σ2 (root mean square = 0.0002 m/s).</p><p>Keywords: shallow water tides, data assimilation, harmonic analysis.</p>

Complexities of using Discrete Tidal Zoning for High Resolution Surveys in Shallow Water

2001 ◽  
Vol 35 (4) ◽  
pp. 51-57
Author(s):  
Cary R. Wong
Keyword(s):  
High Resolution ◽  
Shallow Water ◽  
Water Level ◽  
Global Positioning System ◽  
Continuous Functions ◽  
Tidal Constituent ◽  
Vertical Control ◽  
Global Positioning ◽  
Time Correction ◽  
Tidal Characteristics

Discrete tidal zoning is a methodology used by the National Ocean Service (NOS) to provide tide reducers for hydrographic surveys. Analyses of historical tide data, models, and other research are used to describe the tidal characteristics of a given survey area to generate co-tidal charts of co-range and co-phase lines. The number of zones for a particular survey depends upon the complexity of the tide in the area. Each zone is described by a range ratio and a time correction to a water level station in operation during the survey. Tide reducers are compiled by applying the appropriate time and range corrections to the sounding data relative to chart datum which is Mean Lower Low Water (MLLW). Shallow water areas typically have the most complex tidal characteristics where the amplitude of the tide reducers can be a significant percentage of the overall sounding depth and can dominate the overall error budget. In high resolution surveys using multi-beam technology, discrete tidal zoning introduces unwanted jumps when soundings cross from one zone to another. NOS is pursuing research into the application of smooth continuous functions for tide reducers to replace discrete tidal zoning. NOS is developing tools such as Tidal Constituent and Residual Interpolation (TCARI) and Kinematic Global Positioning System (GPS) for operational vertical control. However, these tools still require water level station installations prior to the survey for the development of tidal datum ties to geodetic datum using GPS and to map MLLW relative to the ellipsoid.

scholarly journals STUDY COMPONENTS OF SHALLOW WATER TIDE (OVER AND COMPOUND TIDES) 1 DIMENSIONAL CHANNEL MODEL BY USING VARIATIONAL DATA ASSIMILATION METHOD

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Evie H. Sudjono ◽  
A. Setiawan ◽  
S. Hadi ◽  
N. S. Ningsih
Keyword(s):  
Data Assimilation ◽  
Harmonic Analysis ◽  
Shallow Water ◽  
Root Mean Square ◽  
Channel Model ◽  
Variational Data Assimilation ◽  
Mean Square ◽  
Tidal Constituent ◽  
Sea Transportation ◽  
Improve Accuracy

Shallow water tides are very important to improve accuracy of tidal predictions. It is used by port interest, sea transportation, fishing industry, coastal engineering, etc. Simulation of shallow water tides was obtained from harmonic analysis of 1 dimensional channel model (12 grid) by using variational data assimilation (grid 3 and 8). Two partial tides with angular frequencies σ1 = 1,4x10-4 and σ2 = 1,6x10-4 rad/sec and amplitude A1 = 1x10-8 and A2 = 0,5x10-8 meters are used for defining external forcing in the model domain. When inspecting the amplitudes of both partial tides σ1 and σ2 and some of their dominant over- and compound tides (σ3 = 2σ1-σ2 and σ4 = 3σ1), in general the “to be corrected” solution can be improved significantly. Root mean square (rms) error of tidal constituent σ1 between the “reference” and the “to be corrected” without data assimilation is 0,1075 m/sec, and for σ2 is 0,0440 m/sec, respectively. On the other hand, the harmonic analysis of the phase of tidal constituent σ1 showed a good result (root mean square = 0.0000 m/s) and for σ2 (root mean square = 0.0002 m/s).Keywords: shallow water tides, data assimilation, harmonic analysis.

Spatial assemblage structure of shallow-water reef fish in Southwest Australia

2020 ◽  
Vol 649 ◽  
pp. 125-140
Author(s):  
DS Goldsworthy ◽  
BJ Saunders ◽  
JRC Parker ◽  
ES Harvey
Keyword(s):  
Shallow Water ◽  
Reef Fish ◽  
Marine Environment ◽  
Fish Assemblages ◽  
Canopy Cover ◽  
Reef Fishes ◽  
Reef Fish Assemblage ◽  
Reef Type ◽  
Present Distribution ◽  
Southwest Australia

Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non-E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.

Low mode acoustics of shallow water waveguides

2011 ◽  
Vol 181 (11) ◽  
pp. 1222 ◽  
Author(s):  
Aleksandr G. Luchinin ◽  
Aleksandr I. Khil'ko
Keyword(s):  
Shallow Water
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