Ralston
David K.
Ralston
David K.
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DatasetMobile Bay 2021 synthetic aperture radar images(Woods Hole Oceanographic Institution, 2024-02-02) Ralston, David K. ; Geyer, W. Rockwell ; Wackerman, ChristopherThis dataset includes satellite synthetic aperture radar images (SAR) that were obtained for the region around the mouth of Mobile Bay during the period April-June 2021. Images were collected to identify the location of oceanographic fronts associated with the outflow plume of Mobile Bay. SAR images show density fronts as regions of increased radar cross-section, i.e. image brightness.
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DatasetData and numerical methods for determining the dynamics and kinematics of Newark Bay, NJ( 2019-07-30) Corlett, W. Bryce ; Geyer, W. Rockwell ; Chant, Robert J. ; Ralston, David K. ; Sommerfield, Christopher K.These observational data and numerical methods were used to investigate the subtidal salt balance of Newark Bay, a sub-estuarine network connected to the Hudson River estuary through New York Harbor. The moored data were collected in 2008 by Chant and Sommerfield, and in 2016 by Corlett, Geyer, and Ralston. Corlett devised the included numerical methods. Shipboard measurements of the vertical salinity profile near each mooring were used to reconstruct the tidally-varying vertical salinity profile from near-bed and near-surface salinity measurements at each mooring. The effects of tidal processes, such as frontal advection, on the exchange flow were investigated by applying the isohaline total exchange flow (TEF) framework to the mooring-based observations in multiple reaches of the estuarine network. In addition, a TEF-based salt balance was derived for the purpose of directly comparing the TEF framework with the standard Eulerian framework.
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DatasetNorth River estuary 2017 dataset(Woods Hole Oceanographic Institution, 2021-03-07) Geyer, W. Rockwell ; Ralston, David K. ; Kranenburg, Wouter M. ; Garcia, Adrian Mikhail P. ; Bo, TongThese are the observational data collected in 2017 from the North River estuary. Data files include the long-term (LT) CTD and Aquadopp measurements from April to July, the short-term (STI from April to May and STII in late July) CTD measurements, eight shipboard CTD and ADCP surveys in April, May and July, the ADV measurements in late July, the North River mid-estuary region bathymetry, and the North River discharge (from USGS measurements).
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DatasetMechanisms of exchange flow in an estuary with a narrow, deep channel and wide, shallow shoals(Woods Hole Oceanographic Institution, 2020-01-31) Geyer, W. Rockwell ; Ralston, David K. ; Chen, Jia-LinDelaware Bay is a large estuary with a deep, relatively narrow channel and wide, shallow banks, providing a clear example of a “channel-shoal” estuary. This numerical modeling study addresses the exchange flow in this channel-shoal estuary, specifically to examine how the lateral geometry affects the strength and mechanisms of exchange flow. We find that the exchange flow is exclusively confined to the channel region during spring tides, when stratification is weak, and it broadens laterally over the shoals during the more stratified neap tides, but still occupies a small fraction of the total width of the estuary. Exchange flow is relatively weak during spring tides, resulting from oscillatory shear dispersion in the channel augmented by weak Eulerian exchange flow. During neap tides, stratification and shear increase markedly, resulting in a strong Eulerian residual shear flow, with a net exchange flow roughly 5 times that of the spring tide. During both spring and neap tides, lateral salinity gradients generated by differential advection at the edge of the channel drive a tidally oscillating cross-channel flow, which strongly influences the stratification, along-estuary salt balance and momentum balance. The lateral flow also causes the phase variation in salinity that results in oscillatory shear dispersion during both spring and neap tides and is a significant advective momentum source driving the residual circulation. Thus, although the shoals make a negligible direct contribution to the exchange flow, the salinity gradients between the channel and the shoal are critical to the stratification and exchange flow within the estuarine channel.
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DatasetHudson River estuary 2004 field experiment(Woods Hole Oceanograpic Institution, 2023-08-08) Lerczak, James A. ; Ralston, David K. ; Geyer, W. Rockwell ; Conley, Margaret M.This dataset includes data from moorings and shipboard observations in the Hudson River estuary during the spring and summer of 2004. The moorings were deployed in the thalweg at 7 sites for 108 days and included a combination of bottom temperature, conductivity, and pressure measurements as well as upward-looking ADCPs. Each mooring site also had near-surface temperature and conductivity measurements. Shipboard CTD surveys were carried out along the estuary on 7 days just after the deployment and just before the recovery of the moorings.