Physical Sciences and Mathematics Commons^™

Linking Sediment Transport And Stratigraphy On The Continental Shelf, Pl Wilberg, Da Cacchione, Rw Sternberg, L. Donelson Wright

VIMS Articles

The goal of the shelf sediment dynamics component of STRATAFORM is to link sediment transport processes active on the continental shelf to the formation and preservation of event beds in shelf sediment deposits. An approach combining shelf sediment-transport models with high-resolution measurements of water-column and bed properties over periods from several months to several years allows us to make quantitative estimates of bed modification caused by sediment resuspension during episodic transport events. These modifications include erosion and deposition of bed material, formation of graded storm beds, and changes in small-scale bed surface morphology. The characteristics of the resulting “event bed” …

Ocean Biogeochemical Fluxes - New Production And Export Of Organic-Matter From The Upper Ocean, Hw Ducklow

VIMS Articles

Studies of ocean biogeochemical fluxes have been energized in this decade, by the urgency of our need to understand and predict the effects of continued CO₂accumulation in the atmosphere, by the global perspectives offered by satellite views of ocean color and related physical fields (McClain et al. 1991; Yoder et al. 1992; Mitchell 1994), and by the successful implementation of the Joint Global Ocean Flux Study (JGOFS; Bowles and Livingston, 1993). In this review, I focus on oceanic new production, originally defined as the fraction of primary production supported by inputs of ‘new’ nitrogen from outside the euphotic …

Calcium Carbonate Sedimentation In The Global Ocean: Linkages Between The Neritic And Pelagic Environments, John D. Milliman, Andre W. Droxler

VIMS Articles

Other than fluvial sediment, calcium carbonate (CaCO3) is the greatest source of sediment in the present-day ocean. Interest in carbonate sedimentation extends beyond geologists because the carbonate system involves biologic and geochemical
processes. Carbonate production, for example, releases CO2 but its accumulation becomes a major sink for inorganic carbon.

Unlike fluvial sediments, modern carbonates accumulate more or less equally in the neritic and pelagic environments. Neritic carbonates (benthic) are characterized by rapid production of (mostly) metastable aragonite and magnesian calcite:pelagic production of (primarily) calcite in the open ocean occurs at much slower rates but overmuch larger areas than does neritic …

Tidal Propagation In Strongly Convergent Channels, Carl T. Friedrichs, David G. Aubrey

VIMS Articles

Simple first‐ and second‐order analytic solutions, which diverge markedly from classical views of cooscillating tides, are derived for tidal propagation in strongly convergent channels. Theoretical predictions compare well with observations from typical examples of shallow, “funnel‐shaped” tidal estuaries. A scaling of the governing equations appropriate to these channels indicates that at first order, gradients in cross‐sectional area dominate velocity gradients in the continuity equation and the friction term dominates acceleration in the momentum equation. Finite amplitude effects, velocity gradients due to wave propagation, and local acceleration enter the equations at second order. Applying this scaling, the first‐order governing equation becomes …

Marine Ecosystem Research At The Weddell Sea Ice Edge: The Ameriez Program, Walker O. Smith Jr., Dl Garrison

VIMS Articles

The explorers and naturalists who first visited Antarctica were struck by the large numbers of whales, seals and seabirds in such a harsh environment (summarized in Everson, 1977). Scientific expeditions in the twentieth century confirmed these observations, and also established that an even greater abundance of many different trophic levels occurred at the ice edge. Hart (1942) noted that phytoplankton were more abundant near the ice edge mad suggested that there was a distinct ice-edge flora, and Marr (1962) noted that krill (Euphausia superba) were concentrated at the interface between pack ice and open water. Routh (1949) observed …

The Formation Of Longitudinal Fronts In A Coastal Plain Estuary, Linda M. Huzzey, John M. Brubaker

VIMS Articles

Longitudinal estuarine fronts, aligned parallel to the axis of the estuary, are characteristic of the York River. Their time scale for genesis and decay is of the order of hours; they are usually located at the inner edge of the shoals or over the main channel. Field measurements have shown marked intratidal differences in density and current speeds across this estuary. These can be correlated with changes in depth and the strength of the advective processes. Differential advection between the channel and shoal regions, when acting upon a constant longitudinal density gradient, is shown to be of sufficient magnitude to …

Air Chemistry Over The Tropical Forest Of Guyana, Gl Gregory, Rc Harriss, Rw Talbot, Ra Rasmussen, M Garstang, Mo Andrae, Rr Hinton, Et Al

VIMS Articles

No abstract provided.

Mid‐Level Intrusions At The Continental Shelf Edge, Christopher S. Welch

VIMS Articles

Observations across the continental shelf offshore from New Jersey in late summer 1976 show an intrusion of saline water at the mid level of the water column across the shelf edge front, which appears in density only as an offshore thickening of the pycnocline. This internal density field produces horizontal pressure gradient forces within the pycnocline in the onshore direction. These forces, in the linearized equation of motion with a constant eddy viscosity, drive a circulation which resembles a double Ekman spiral for internal pressure vertical distributions which are thin with respect to the Ekman depth. For thick pressure distributions, …

Groundwater Flow In A Sandy Tidal Beach 2. Two-Dimensional Finite Element Analysis., C. S. Fang, S. N. Wang, W. Harrison

VIMS Articles

Two-dimensional finite element techniques are described that model closely the complicated fluctuations osbserved in the water table of an ocean beach. The use of triangular elements permits the specification of more realistic boundary conditions than the use of line elements in a one-dimensional model. Also, results obtained from the two-dimensional model for the region closet o the ocean compare more favorably with field data than results obtained from the one-dimensional finite element model.

Groundwater Flow In A Sandy Tidal Beach 1. One-Dimensional Finite Element Analysis, W. Harrison, C. S. Fang, S. N. Wang

VIMS Articles

A 31-day time series of observations of beach water table and tidal fluctuations was obtained from 13 wells along a profile perpendicular to the shoreline at Virginia Beach, Virginia. Finite element techniques were applied to solve the one-dimensional, unsteady state, nonlinear equation for groundwater movement. For the finite element analysis, the semi-infinite mass (unconfined aquifer) had to be replaced by a finite mass. The boundary conditions were found from the field data by directly solving the flow equation with a finite difference technique. The finite element method, using the variational principle, provided a reasonable solution and afforded economy in computer …

Predictor Equations For Beach Processes And Responses, W. Harrison, N. A. Pore, D. R. Tuck Jr.

VIMS Articles

A stepwise (linear) multiple regression procedure is applied to 11 environmental variables (or predictors) in the beach-ocean-atmosphersey stema t Virginia Beach, Virginia, for the following five predictands: mean longshore current velocity, mean bottom slope in the shoaling-wave zone, average mean grain size in the shoaling-wave zone, and beach deposition and beach erosion on the lower foreshore. Predictors consist of variables related to beach geometry, local water properties, local wind conditions, tidal fluctuations, and wave characteristics The resultant equations are tested against a set of independent data and, with one exception, agree reasonably. It is believed that if the data set …

Investigations Of Inner Continental Shelf Waters Off Lower Chesapeake Bay. Part V. Seasonality Of The Diatom Genus Chaetoceros, Richard A. Mulford

VIMS Articles

Twenty-five species of Chaetoceros were taken from monthly samples during one year in the Atlantic Ocean off the Virginia capes. Results indicate the fall-winter period to be the most productive in numbers and species diversity. The Chaetoceros population was primarily a mixture of cold- and warm-water forms, with two species, C. decipiens and C. didymus, being most abundant and widespread. A cyclic seasonal pattern based on past records is suggested for the genus along the east coast of the United States. Seasonality, temperature, and salinity ranges for each species are presented.