Dispersal of the Hudson River Plume in the New York Bight: Synthesis of Observational and Numerical Studies During LaTTE (original) (raw)
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Laboratory experiments simulating a coastal river inflow
Journal of Fluid Mechanics, 2006
The dynamics of buoyant water entering a rotating basin are studied using a series of laboratory experiments designed to elucidate the alongshore transport mechanisms in river plumes. Inflowing water, which is discharged perpendicular to the tank wall, is observed to form a growing anticyclonic bulge and a coastal current downstream of the bulge. Detailed simultaneous measurements of the velocity and buoyancy fields in the plume confirm that the bulge momentum is in a gradient-wind balance and the coastal current is geostrophic. The growth of the bulge and accumulation of fluid within it coincides with a reduction in coastal current transport to approximately 50 % of the inflow discharge. The bulge is characterized by a depth scale, h, which is proportional to the geostrophic depth, h g , and two time-dependent horizontal length scales, y c , the displacement of the bulge centre from the wall, and r b , the effective radius of the bulge. These two length scales are proportional to the inertial radius, L i , and the local Rossby radius, L b , respectively. When r b y c , the bulge is held tightly to the wall, and a relatively large fraction of the inflow discharge is forced into the coastal current. For plumes with y c approaching r b , the bulge is further from the wall, and the coastal current flux is reduced. Once y c /r b > 0.7, the bulge separates from the wall causing flow into the coastal current to cease and the bulge to become unstable. In this state, the bulge periodically detaches from and re-attaches to the wall, resulting in pulsing transport in the coastal current. Scaling of the bulge growth based on h g , L i and L b predicts that it will increase as Ro 1/4 , where Ro is the inflow Rossby number. The bulge growth, inferred from direct measurements of the coastal current transport, is proportional to Ro 0.32 and agrees with the predicted dependence within the experimental error. † Present addess:
Bulge Formation of a Buoyant River Outflow
Journal of Geophysical Research, 2008
Observations taken during the Lagrangian Transport and Transformation Experiment (LaTTE) in 2005 indicated that the Hudson's river outflow formed a bulge of recirculating fluid that limits the volume of fresh water that is advected away in a coastal current. Focusing on an event that began with downwelling winds we made estimates of the freshwater flux in the coastal current and the fresh water inventory of the bulge. The coastal current was characterized by a surface advected plume in thermal wind balance. However, the freshwater transport in the coastal current was less than 1/2 of the total freshwater outflow. The bulge extended 30 km from the coast and 40 km in the alongshore direction and was evident in ocean color imagery. Recirculation in the bulge region was also apparent in daily averaged surface current radar data, but this flow pattern was obscured in the hourly data by tidal and wind-forcing even in the diurnal band. Nevertheless, many aspects of the Hudson's outflow are consistent with recent laboratory experiments and numerical simulations of buoyant discharges. The growing bulge transports the river's outflow to the head of the Hudson shelf valley where it crosses the 50 m isobath. Previous work in this region indicates that frontal features reside along this isobath. We observed fresh water being transported along this isobath and is suggestive of a rapid cross-shelf transport pathway for fresh water. Both the bulge formation and cross-shelf transport have significant biogeochemical implications.
The Response of Lateral Flow to Peak River Discharge in a Macrotidal Estuary
Water, 2020
The Ou River, a medium-sized river in southeastern China, is selected to study the lateral flow response to rapidly varied river discharge, i.e., peak river discharge (PRD). A three-dimensional model based on the Finite-Volume Community Ocean Model is validated by in situ measurements from 15 June to 16 July 2005. PRD, which considers the extra buoyancy and longitudinal momentum in a short time, rebuilds the stratification and lateral flow. PRD, compared with low-discharge, generally makes stratification stronger and lateral flow weaker. PRD mainly rebuilds lateral flow by changing lateral advection, lateral Coriolis, and lateral-barotropic pressure gradient terms. After PRD, the salinity recovery time is longer than that of the flow because the impact on buoyancy lasts longer than that on longitudinal flow. Longitudinal flow is mostly affected by the momentum transferred during PRD; therefore, the recovery time is close to the flooding duration. However, the lateral flow is affecte...
River, Coastal and Estuarine Morphodynamics
2001
Library of Congress Cataloging-in-Publication Data River, coastal and estuarine morphodynamcs I Giovanni Seminara; Paolo Blondeaux. p.cm. "This book collects review papers on most of the topics covererd by the invited lecturers at the IAHR Symposium on River, Coastal, and Estuarine Morphodynamics, held in Genova (Italy) on September 6"'-10"', 1999"-Pref. Includes bibliographical references.
Inflows/outflows at the transition between a coastal plain estuary and the coastal ocean
Continental Shelf Research, 1996
A series of numerical experiments were performed to study the dynamics at the transition region between a wide (Kelvin number between 2 and 3.6) coastal plain estuary and the adjacent coastal ocean. In particular, the separate effects of modifying the seaward discharge within the estuary, the coastal ambient flow, the coastal ocean bottom slope, and the initial salinity gradient were investigated. The numerical experiments were carried out in a flat-bottom estuary with a N-S orientation that is connected to the ocean in the E-W direction. Results show that increased seaward discharge at the estuary upstream boundary reduces volume inflow and increases volume outflow through a cross-section at the estuary mouth. A southward coastal ambient flow is responsible for increased volume inflow, for keeping estuarine outflow within a few kilometers from the coast, for increasing surface flow divergence at the estuary mouth, and for hindering inflow that originates to the south of the estuary. When the coastal ambient flow is suppressed, the bottom slope of the coastal ocean causes negligible effects to volume transports, to the dynamical balances, and to the shape and extent of inflows/outflows compared to results over a flat bottom. These effects of the bottom slope become non-negligible but are still minor when thc coastal ambient flow is active. A pulse of buoyant water at the estuary upstream boundary causes, after the discharge stops, increased volume inflow with respect to other experiments. Increased salinity gradients produce enlargements to the deformation radii, the volumes exchanged, and the regions directly influenced by inflows and outflows.
Advances in morphodynamics of tidal rivers and estuaries
Using examples from research project and studies on the morphological evolution of sandy estuaries and coastal lagoons in The Netherlands, the added value of simultaneously applying different methods of analysis or prediction is demonstrated. Where the methods overlap, they mutually validate each other, where they are complementary, they provide more complete information that may reduce uncertainty. INTRODUCTION Many estuaries around the world are at the same time economically important links between land and sea, providing access to harbours and inland waterways, and valuable natural environments, providing shelter, feeding and breeding grounds and nurseries to a wide variety of species. In the past, these functions could mostly be combined without much trouble, but now that man is interfering with these systems at an ever larger scale and is putting ever higher demands on navigability for ever larger ships, many estuarine ecosystems are stressed to the extreme. Mitigating measures...
Circulation in the Hudson Estuary
Annals of the New York Academy of Sciences, 1974
This paper describes the hydrodynamic characteristics of partially stratified water bodies, as typified by the Hudson River, and presents a number of methods of establishing a quantitative relationship of density-induced velocity and circulation to salinity levels, freshwater runoff, and tidal characteristics. These methods utilize known or measurable physical and hydraulic parameters to determine the density-induced circulation (DIC) and mixing characteristics of estuaries. The DIC concept plays an important role in estuarine discharges, and has been used to obtain an estimate of the flow available for dilution in estuaries. Dilution flows associated with this DIC pattern may be many times that of the upland runoff. They have been observed to be higher by factors of from 10 to 40 in several estuaries. A brief description of estuarine circulation patterns is given in the second section b of this paper. The third section c addresses itself to circulation patterns in partially stratified estuaries. These patterns are related to the net velocity distribution, which by and large is a result of dynamic interactions between the 'FIGURE 1 represents a revision of a similar relationship that appears in earlier Quirk, Lawler & Matusky reports.' ' 9 ' This revision includes measurements made in recent years and a refined estimate of the Lower Hudson flow yield factor.
Earth Surface Processes and Landforms, 2020
This Special Issue collects 17 selected contributions from participants to the 10th edition of the RCEM (River, Coastal and Estuarine Morphodynamics) Symposium, organized in Padova-Trento (Italy) in September 2017. The series of biennial RCEM Symposia has the key goal of enhancing interaction and promoting integration among the scientific communities focused on the morphological dynamics of river, coastal and estuarine environments, though various combinations of theoretical, observational, experimental and modelling approaches. The 17 contributions to this Special Issue contain 4 state of science reviews and overall offer a broad view of the cross-cutting perspective adopted when addressing morphodynamics. Such perspective accounts for the mutual interplay between morphology, fluid dynamics and other environmental factors, and has presently become a widespread paradigm to address landscape evolution.