Multiple time‐reversed guide‐sources in shallow water

2003 ◽  
Vol 114 (4) ◽  
pp. 2399-2399
Author(s):  
Charles F. Gaumond ◽  
David M. Fromm ◽  
Joseph F. Lingevitch ◽  
Roger C. Gauss ◽  
Richard Menis
Keyword(s):  
Shallow Water ◽  
Multiple Time

Detection enhancement using multiple time‐reversed guide sources in shallow water

2004 ◽  
Vol 116 (4) ◽  
pp. 2574-2574 ◽  
Author(s):  
David C. Calvo ◽  
Charles F. Gaumond ◽  
David M. Fromm ◽  
Joseph F. Lingevitch ◽  
Richard Menis ◽  
...  
Keyword(s):  
Shallow Water ◽  
Multiple Time ◽  
Detection Enhancement

Detection enhancement using multiple time-reversed guide sources in shallow water

2006 ◽  
Author(s):  
D.C. Calvo ◽  
C.F. Gaumond ◽  
D.M. Fromm ◽  
R. Menis ◽  
J.F. Lingevitch ◽  
...  
Keyword(s):  
Shallow Water ◽  
Multiple Time ◽  
Detection Enhancement

Resonant fast–slow interactions and breakdown of quasi-geostrophy in rotating shallow water

2016 ◽  
Vol 788 ◽  
pp. 492-520 ◽  
Author(s):  
Jim Thomas
Keyword(s):  
Evolution Equation ◽  
Shallow Water ◽  
Water System ◽  
Wave Interaction ◽  
Multiple Time ◽  
Slow Dynamics ◽  
Balanced Flow ◽  
Rotating Shallow Water ◽  
Fast Waves ◽  
Wave Modes

In this paper we investigate the possibility of fast waves affecting the evolution of slow balanced dynamics in the regime $Ro\sim Fr\ll 1$ of a rotating shallow water system, where $Ro$ and $Fr$ are the Rossby and Froude numbers respectively. The problem is set up as an initial value problem with unbalanced initial data. The method of multiple time scale asymptotic analysis is used to derive an evolution equation for the slow dynamics that holds for $t\lesssim 1/(fRo^{2})$, $f$ being the inertial frequency. This slow evolution equation is affected by the fast waves and thus does not form a closed system. Furthermore, it is shown that energy and enstrophy exchange can take place between the slow and fast dynamics. As a consequence, the quasi-geostrophic ideology of describing the slow dynamics of the balanced flow without any information on the fast modes breaks down. Further analysis is carried out in a doubly periodic domain for a few geostrophic and wave modes. A simple set of slowly evolving amplitude equations is then derived using resonant wave interaction theory to demonstrate that significant wave-balanced flow interactions can take place in the long-time limit. In this reduced system consisting of two geostrophic modes and two wave modes, the presence of waves considerably affects the interactions between the geostrophic modes, the waves acting as a catalyst in promoting energetic interactions among geostrophic modes.

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.

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