The freshwater transport and dynamics of the western Maine coastal current

2004 ◽  
Vol 24 (12) ◽  
pp. 1339-1357 ◽  
Author(s):  
W.R. Geyer ◽  
R.P. Signell ◽  
D.A. Fong ◽  
J. Wang ◽  
D.M. Anderson ◽  
...  
Keyword(s):  
Coastal Current ◽  
Freshwater Transport

scholarly journals Impact of Shelf Valleys on the Spread of Surface Trapped River Plumes

2020 ◽  
Author(s):  
Canbo Xiao ◽  
Weifeng (Gordon) Zhang ◽  
Ying Chen
Keyword(s):  
Incident Angle ◽  
Coastal Current ◽  
Current Sensitivity ◽  
Coriolis Parameter ◽  
River Plumes ◽  
Estuary Mouth ◽  
Freshwater Transport ◽  
Bulge Region ◽  
Freshwater Plumes ◽  
Topographic Influence

AbstractThis study focuses on mechanisms of shelf valley bathymetry affecting the spread of riverine freshwater in the nearshore region. In the context of Changjiang River, a numerical model is used with different no-tide idealized configurations to simulate development of unforced river plumes over a sloping bottom, with and without a shelf valley off the estuary mouth. All simulated freshwater plumes are surface-trapped with continuously growing bulges near the estuary mouth and narrow coastal currents downstream. The simulations indicate that a shelf valley tends to compress the bulge along the direction of the valley long axis and modify the incident angle of the bulge flow impinging toward the coast, which then affects the strength of the coastal current. The bulge compression results from geostrophic adjustment and isobath-following tendency of the depth-averaged flow in the bulge region. Generally, the resulting change in the direction of the bulge impinging flow enhances down-shelf momentum advection and freshwater delivery into the coastal current. Sensitivity simulations with altered river discharges (Q), Coriolis parameter, shelf bottom slope, valley geometry, and ambient stratification show that enhancement of down-shelf freshwater transport in the coastal current, ΔQc, increases with increasing valley depth within the bulge region and decreasing slope Burger number of the ambient shelf. Assuming potential vorticity conservation, a scaling formula of ΔQc?Q is developed, and it agrees well with results of the sensitivity simulations. Mechanisms of valley influences on unforced river plumes revealed here will help future studies of topographic influence on river plumes under more realistic conditions.

scholarly journals Enhancement of Alongshore Freshwater Transport in Surface-Advected River Plumes by Tides

2014 ◽  
Vol 44 (11) ◽  
pp. 2951-2971 ◽  
Author(s):  
Shih-Nan Chen
Keyword(s):  
Numerical Study ◽  
Incident Angle ◽  
Ocean Modeling ◽  
Positive Pressure ◽  
Coastal Current ◽  
Current Transport ◽  
Coastal Currents ◽  
Regional Ocean Modeling System ◽  
Tidal Forcing ◽  
Freshwater Transport

Abstract A recent numerical study by Isobe showed that imposing alongshore tidal forcing on buoyant coastal discharge enhances the net freshwater transport in the coastal currents. The mechanisms for this transport enhancement are studied using a three-dimensional, primitive equation ocean model [Regional Ocean Modeling System (ROMS)]. Lagrangian drifters are used to trace the freshwater transport paths. It is found that the river plume bulge circulation largely follows the rigid-body motion (i.e., constant vorticity). The buoyant fluid near the bulge’s outer edge is thinner and faster, behaving as a baroclinic jet. The bulge currents then split after impinging on the coast. The outer fluid feeds the downshelf-flowing coastal currents, while the inner fluid recirculates to form the bulge. The coastal current transport estimated from the present and prior studies corresponds well to a baroclinic jet theory, with the incident angle of bulge currents at the coast being a key parameter. Without tides, the bulge is approximately circular. The incident angle measured with respect to the cross-shore axis is small. With tides, the convergence of tidal momentum fluxes near the upshelf plume front leads to a positive pressure anomaly, which acts to compress the bulge shoreward. As a result, the incident angle increases, which in turn enhances the downshelf momentum input, thus increasing the freshwater transport in the coastal currents. Finally, the parameter space for coastal current transport in the presence of tidal forcing is explored with a conceptual model. A few observational examples are given.

scholarly journals Detiding Measurement on Transport of the Changjiang-Derived Buoyant Coastal Current

2013 ◽  
Vol 43 (11) ◽  
pp. 2388-2399 ◽  
Author(s):  
Hui Wu ◽  
Bing Deng ◽  
Rui Yuan ◽  
Jun Hu ◽  
Jinghua Gu ◽  
...  
Keyword(s):  
Large River ◽  
Volume Transport ◽  
Surface Velocity ◽  
Coastal Current ◽  
In Situ Data ◽  
Freshwater Transport ◽  
Chinese Coast ◽  
First Time ◽  
O 10

Abstract Measuring the transport of the Changjiang (also known as the Yangtze) River–derived buoyant coastal current, that is, the Min–Zhe Coastal Current, is of great importance for understanding the fate of terrestrial materials from this large river into the open ocean, but it is usually difficult to achieve because of the energetic tidal currents along the Chinese coast. In February 2012, a detiding cruise survey was carried out using the phase-averaging method. For the first time, this coastal current has been quantified with in situ data and has been shown to have a volume transport of 0.215 Sv (1 Sv ≡ 106 m3 s−1) and a maximum surface velocity of ~50 cm s−1. The ratio between the volume transport of the buoyant coastal current and that of the Changjiang is O(10). Freshwater transport by the buoyant coastal current accounts for over 90% of the Changjiang River's discharge. Buoyancy and winds are both important in driving this current.

The impact of spatial wind variations on freshwater transport by the Alaska Coastal Current

2008 ◽  
Vol 66 (6) ◽  
pp. 899-925 ◽  
Author(s):  
John Rogers-Cotrone ◽  
Alexander E. Yankovsky ◽  
Thomas J. Weingartner
Keyword(s):  
Coastal Current ◽  
Freshwater Transport ◽  
Alaska Coastal Current ◽  
The Impact

scholarly journals Evolution of the Freshwater Coastal Current at the Southern Tip of Greenland

2018 ◽  
Vol 48 (9) ◽  
pp. 2127-2140 ◽  
Author(s):  
Peigen Lin ◽  
Robert S. Pickart ◽  
Daniel J. Torres ◽  
Astrid Pacini
Keyword(s):  
Velocity Structure ◽  
Greenland Ice Sheet ◽  
Volume Transport ◽  
The Arctic ◽  
Labrador Sea ◽  
Coastal Current ◽  
Velocity Measurements ◽  
The West ◽  
West Side ◽  
Freshwater Transport

AbstractShipboard hydrographic and velocity measurements collected in summer 2014 are used to study the evolution of the freshwater coastal current in southern Greenland as it encounters Cape Farewell. The velocity structure reveals that the coastal current maintains its identity as it flows around the cape and bifurcates such that most of the flow is diverted to the outer west Greenland shelf, while a small portion remains on the inner shelf. Taking into account this inner branch, the volume transport of the coastal current is conserved, but the freshwater transport decreases on the west side of Cape Farewell. A significant amount of freshwater appears to be transported off the shelf where the outer branch flows adjacent to the shelfbreak circulation. It is argued that the offshore transposition of the coastal current is caused by the flow following the isobaths as they bend offshore because of the widening of the shelf on the west side of Cape Farewell. An analysis of the potential vorticity shows that the subsequent seaward flux of freshwater can be enhanced by instabilities of the current. This set of circumstances provides a pathway for the freshest water originating from the Arctic, as well as runoff from the Greenland ice sheet, to be fluxed into the interior Labrador Sea where it could influence convection in the basin.

scholarly journals The Role of Environmental Factors on the Fishery Catch of the Squid Uroteuthis chinensis in the Pearl River Estuary, China

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Pearl River ◽  
Coastal Current ◽  
Catch Per Unit Effort ◽  
Chl A ◽  
The Pearl River Estuary ◽  
The Pearl River

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.

scholarly journals Ensemble forecasting greatly expands the prediction horizon for ocean mesoscale variability

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Prasad G. Thoppil ◽  
Sergey Frolov ◽  
Clark D. Rowley ◽  
Carolyn A. Reynolds ◽  
Gregg A. Jacobs ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Mesoscale Dynamics ◽  
Predictive Skill ◽  
Freshwater Transport ◽  
Prediction Horizon ◽  
Initial Location ◽  
Ocean Models ◽  
High Uncertainty

AbstractMesoscale eddies dominate energetics of the ocean, modify mass, heat and freshwater transport and primary production in the upper ocean. However, the forecast skill horizon for ocean mesoscales in current operational models is shorter than 10 days: eddy-resolving ocean models, with horizontal resolution finer than 10 km in mid-latitudes, represent mesoscale dynamics, but mesoscale initial conditions are hard to constrain with available observations. Here we analyze a suite of ocean model simulations at high (1/25°) and lower (1/12.5°) resolution and compare with an ensemble of lower-resolution simulations. We show that the ensemble forecast significantly extends the predictability of the ocean mesoscales to between 20 and 40 days. We find that the lack of predictive skill in data assimilative deterministic ocean models is due to high uncertainty in the initial location and forecast of mesoscale features. Ensemble simulations account for this uncertainty and filter-out unconstrained scales. We suggest that advancements in ensemble analysis and forecasting should complement the current focus on high-resolution modeling of the ocean.

Observed variability of the West India Coastal Current on the continental shelf from 2010–2017

2021 ◽  
Vol 130 (2) ◽  
Author(s):  
Anya Chaudhuri ◽  
P Amol ◽  
D Shankar ◽  
S Mukhopadhyay ◽  
S G Aparna ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Coastal Current ◽  
The West
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