The impact of internal tides and gravity waves on key acoustic parameters and acoustic transmission loss near the Amazon shelf

2021 ◽  
Vol 150 (4) ◽  
pp. A25-A25
Author(s):  
Martha Schönau ◽  
Emanuel Coelho ◽  
Robert Helber ◽  
Jay Shriver ◽  
Kathryn Verlinden
Keyword(s):  
Gravity Waves ◽  
Transmission Loss ◽  
Internal Tides ◽  
Acoustic Transmission ◽  
Acoustic Parameters ◽  
Amazon Shelf ◽  
The Impact

scholarly journals Impact of Gravity Waves on Marine Stratocumulus Variability

2012 ◽  
Vol 69 (12) ◽  
pp. 3633-3651 ◽  
Author(s):  
Qingfang Jiang ◽  
Shouping Wang
Keyword(s):  
Gravity Waves ◽  
Vertical Motion ◽  
Liquid Water Path ◽  
Marine Stratocumulus ◽  
Large Eddy Simulation Model ◽  
Cloud Albedo ◽  
Eddy Simulation ◽  
Aerosol Number Concentration ◽  
Wave Induced ◽  
The Impact

Abstract The impact of gravity waves on marine stratocumulus is investigated using a large-eddy simulation model initialized with sounding profiles composited from the Variability of American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study Regional Experiment (VOCALS-Rex) aircraft measurements and forced by convergence or divergence that mimics mesoscale diurnal, semidiurnal, and quarter-diurnal waves. These simulations suggest that wave-induced vertical motion can dramatically modify the cloud albedo and morphology through nonlinear cloud–aerosol–precipitation–circulation–turbulence feedback. In general, wave-induced ascent tends to increase the liquid water path (LWP) and the cloud albedo. With a proper aerosol number concentration, the increase in the LWP leads to enhanced precipitation, which triggers or strengthens mesoscale circulations in the boundary layer and accelerates cloud cellularization. Precipitation also tends to create a decoupling structure by weakening the turbulence in the subcloud layer. Wave-induced descent decreases the cloud albedo by dissipating clouds and forcing a transition from overcast to scattered clouds or from closed to open cells. The overall effect of gravity waves on the cloud variability and morphology depends on the cloud property, aerosol concentration, and wave characteristics. In several simulations, a transition from closed to open cells occurs under the influence of gravity waves, implying that some of the pockets of clouds (POCs) observed over open oceans may be related to gravity wave activities.

Internal Wave Generation by a Combination of Tidal and Steady Currents

2021 ◽  
Author(s):  
Xiaolin Bai ◽  
Kevin Lamb ◽  
José da Silva
Keyword(s):  
Internal Wave ◽  
Wave Generation ◽  
Satellite Observations ◽  
Internal Tides ◽  
Small Scale ◽  
Western Boundary ◽  
Boundary Current ◽  
Reanalysis Dataset ◽  
Amazon Shelf ◽  
Internal Wave Generation

<p>In the presence of topography, two main contributors for internal wave energy are tide-topography interaction transferring energy from the barotropic tide to internal tides, and lee wave generation when geostrophic currents or eddying abyssal flows interact with topography. In the past few decades, many studies considered the respective contribution of the oscillating flows or steady background flows, but few investigations have considered both.  </p><p>In this talk, we consider the joint effects of tidal and steady currents to investigate internal wave generation and propagation on the Amazon shelf, a hotspot for internal solitary wave (ISW) generation. The Amazon Shelf is off the mouth of the Amazon River in the southwest tropical Atlantic Ocean, affected by strong tidal constituents over complex bottom bathymetry and a strong western boundary current, the North Brazilian Current (NBC). Both satellite observations and numerical modelling are used in this study. Satellite observations provide a clear visualization of the wave characteristics, such as temporal and spatial distributions, propagating direction and its relation to background currents. Based on parameters from satellite observations and reanalysis dataset, we set up a model to numerically investigate the dynamics of the ISW generation. We demonstrate that the small-scale topography contributes to a rich generation of along-shelf propagating ISW, which significantly contribute to the ocean mixing and potentially cause sediment resuspension. Moreover, the ISW-induced currents also contribute to the sea surface wave breaking as observed by satellite measurements. In addition, statistics based on a decade of satellite images and numerical investigations on seasonal variations of the ISWs and the NBC improve our understanding of the generation and evolution of these nonlinear internal waves in the presence of background currents.</p>

scholarly journals VISIR-1.b: ocean surface gravity waves and currents for energy-efficient navigation

2019 ◽  
Vol 12 (8) ◽  
pp. 3449-3480 ◽  
Author(s):  
Gianandrea Mannarini ◽  
Lorenzo Carelli
Keyword(s):  
Energy Efficiency ◽  
Gravity Waves ◽  
Ocean Surface ◽  
Surface Gravity ◽  
Ocean Current ◽  
Ship Routing ◽  
Surface Gravity Waves ◽  
Waves And Currents ◽  
The Impact

Abstract. The latest development of the ship-routing model published in Mannarini et al. (2016a) is VISIR-1.b, which is presented here. The new version of the model targets large ocean-going vessels by considering both ocean surface gravity waves and currents. To effectively analyse currents in a graph-search method, new equations are derived and validated against an analytical benchmark. A case study in the Atlantic Ocean is presented, focussing on a route from the Chesapeake Bay to the Mediterranean Sea and vice versa. Ocean analysis fields from data-assimilative models (for both ocean state and hydrodynamics) are used. The impact of waves and currents on transatlantic crossings is assessed through mapping of the spatial variability in the tracks, an analysis of their kinematics, and their impact on the Energy Efficiency Operational Indicator (EEOI) of the International Maritime Organization. Sailing with or against the main ocean current is distinguished. The seasonal dependence of the EEOI savings is evaluated, and greater savings with a higher intra-monthly variability during winter crossings are indicated in the case study. The total monthly mean savings are between 2 % and 12 %, while the contribution of ocean currents is between 1 % and 4 %. Several other ocean routes are also considered, providing a pan-Atlantic scenario assessment of the potential gains in energy efficiency from optimal tracks, linking them to regional meteo-oceanographic features.

The effects of pH on acoustic transmission loss in an estuary

2014 ◽  
Vol 136 (4) ◽  
pp. 2156-2156 ◽  
Author(s):  
James H. Miller ◽  
Laura Kloepper ◽  
Gopu R. Potty ◽  
Arthur J. Spivack ◽  
Steven D'Hondt ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Acoustic Transmission ◽  
Effects Of Ph
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