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Geology topics

John C. Warner

Publications and source records attributed to John C. Warner.

78 records · Page 5Linked to original sources
USGS2004

Sediment dynamics in the Adriatic Sea investigated with coupled models

Several large research programs focused on the Adriatic Sea in winter 2002-2003, making it an exciting place for sediment dynamics modelers (Figure 1). Investigations of atmospheric forcing and oceanic response (including wave generation and propagation, water-mass formation, stratification, and circulation), suspended material, bottom boundary layer dynamics, bottom sediment, and small-scale stratigraphy were performed by European and North American researchers participating in several projects. The goal of EuroSTRATAFORM researchers is to improve our ability to understand and simulate the physical processes that deliver sediment to the marine environment and generate stratigraphic signatures. Scientists involved in the Po and Apennine Sediment Transport and Accumulation (PASTA) experiment benefited from other major research programs including ACE (Adriatic Circulation Experiment), DOLCE VITA (Dynamics of Localized Currents and Eddy Variability in the Adriatic), EACE (the Croatian East Adriatic Circulation Experiment project), WISE (West Istria Experiment), and ADRICOSM (Italian nowcasting and forecasting) studies.

Adriatic Sea↗
USGS2002

Effects of tidal current phase at the junction of two straits

Estuaries typically have a monotonic increase in salinity from freshwater at the head of the estuary to ocean water at the mouth, creating a consistent direction for the longitudinal baroclinic pressure gradient. However, Mare Island Strait in San Francisco Bay has a local salinity minimum created by the phasing of the currents at the junction of Mare Island and Carquinez Straits. The salinity minimum creates converging baroclinic pressure gradients in Mare Island Strait. Equipment was deployed at four stations in the straits for 6 months from September 1997 to March 1998 to measure tidal variability of velocity, conductivity, temperature, depth, and suspended sediment concentration. Analysis of the measured time series shows that on a tidal time scale in Mare Island Strait, the landward and seaward baroclinic pressure gradients in the local salinity minimum interact with the barotropic gradient, creating regions of enhanced shear in the water column during the flood and reduced shear during the ebb. On a tidally averaged time scale, baroclinic pressure gradients converge on the tidally averaged salinity minimum and drive a converging near-bed and diverging surface current circulation pattern, forming a "baroclinic convergence zone" in Mare Island Strait. Historically large sedimentation rates in this area are attributed to the convergence zone.

California↗
USGS1997

Sediment transport pathway in the back of a nearly semienclosed subembayment of San Francisco Bay, California

Time series measurements of current velocity, depth and suspended-solids concentration (SSC) were used to obtain suspended-solids fluxes (SSF) during the fall at central Honker Bay and Spoonbill Creek. A wind-induced shear stress increases SSF out of Honker Bay through Spoonbill Creek by combining two effects: (1) wind-wave resuspension of bed sediments, and (2) wind shear raises the water level at the Honker Bay. High SSC water advected from Honker Bay into the Sacramento River does not return on the following ebb tide, which creates the dispersive SSF. The total SSF was always out of Honker Bay during the fall suggesting that high metals and pesticides concentrations are not caused by transport through Spoonbill Creek into Honker Bay.

California↗