The Experts below are selected from a list of 13443 Experts worldwide ranked by ideXlab platform
Zengrui Rong - One of the best experts on this subject based on the ideXlab platform.
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current Wave interaction in the mississippi atchafalaya river plume on the texas louisiana Shelf
Ocean Modelling, 2014Co-Authors: Zengrui Rong, Robert D Hetland, Wenxia Zhang, Xiaoqian ZhangAbstract:Abstract Wave–current interaction over the Texas–Louisiana Shelf, and its effects on the dispersal and mixing of the Mississippi–Atchafalaya river plume, have been investigated using the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) Modeling System. The modeling system is driven by realistic Wave and current conditions at the open boundaries and high frequency1-D wind measured from a nearby meteorological station. Skill analysis demonstrates that the model reproduces the Wave and salinity fields reasonably well. Waves over the Texas–Louisiana Shelf are dominated by locally forced wind seas, and generally propagate in the same direction as the winds. Investigation into the spatial differences in the effect of Waves reveals two distinct dynamical regions: the Chenier Shelf, the Shelf region extending roughly offshore from Sabine Lake to Vermilion Bay, and the Louisiana Bight, the region between the Mississippi Delta and Terrebonne Bay. A variety of model runs are performed, where specific Wave processes are either included or excluded, in order to isolate the processes acting in different regions. The Chenier Shelf is mainly affected by Wave enhanced bottom stress, whereas the Louisiana Bight is mostly affected by the surface Wave induced mixing and 3-D Wave forces. The Wave enhanced bottom stress suppresses cross-shore exchange, and acts to trap more freshwater in the nearshore regions shallower than 50 m over the Chenier Shelf. Wave enhanced bottom stress plays only a minor role in the Louisiana Bight, where the surface-trapped Mississippi plume rarely feels the bottom. The surface intensified Wave mixing and 3-D Wave forces reduce the surface salinity and weaken the stratification in the region associated with the thin recirculating Mississippi plume in the Louisiana Bight. Model results indicate that the surface Wave mixing, the 3-D Wave forces, and the Wave bottom stress exhibit little interaction over the Texas–Louisiana Shelf. Finally, we have demonstrated that the one-way coupling is capable of resolving the majority of Wave effects over the entire Shelf if the seasonal scale is of interest.
Xiaoqian Zhang - One of the best experts on this subject based on the ideXlab platform.
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current Wave interaction in the mississippi atchafalaya river plume on the texas louisiana Shelf
Ocean Modelling, 2014Co-Authors: Zengrui Rong, Robert D Hetland, Wenxia Zhang, Xiaoqian ZhangAbstract:Abstract Wave–current interaction over the Texas–Louisiana Shelf, and its effects on the dispersal and mixing of the Mississippi–Atchafalaya river plume, have been investigated using the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) Modeling System. The modeling system is driven by realistic Wave and current conditions at the open boundaries and high frequency1-D wind measured from a nearby meteorological station. Skill analysis demonstrates that the model reproduces the Wave and salinity fields reasonably well. Waves over the Texas–Louisiana Shelf are dominated by locally forced wind seas, and generally propagate in the same direction as the winds. Investigation into the spatial differences in the effect of Waves reveals two distinct dynamical regions: the Chenier Shelf, the Shelf region extending roughly offshore from Sabine Lake to Vermilion Bay, and the Louisiana Bight, the region between the Mississippi Delta and Terrebonne Bay. A variety of model runs are performed, where specific Wave processes are either included or excluded, in order to isolate the processes acting in different regions. The Chenier Shelf is mainly affected by Wave enhanced bottom stress, whereas the Louisiana Bight is mostly affected by the surface Wave induced mixing and 3-D Wave forces. The Wave enhanced bottom stress suppresses cross-shore exchange, and acts to trap more freshwater in the nearshore regions shallower than 50 m over the Chenier Shelf. Wave enhanced bottom stress plays only a minor role in the Louisiana Bight, where the surface-trapped Mississippi plume rarely feels the bottom. The surface intensified Wave mixing and 3-D Wave forces reduce the surface salinity and weaken the stratification in the region associated with the thin recirculating Mississippi plume in the Louisiana Bight. Model results indicate that the surface Wave mixing, the 3-D Wave forces, and the Wave bottom stress exhibit little interaction over the Texas–Louisiana Shelf. Finally, we have demonstrated that the one-way coupling is capable of resolving the majority of Wave effects over the entire Shelf if the seasonal scale is of interest.
A.t. Morrison - One of the best experts on this subject based on the ideXlab platform.
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development of the bass rake acoustic current sensor measuring velocity in the continental Shelf Wave bottom boundary layer
1997Co-Authors: A.t. MorrisonAbstract:Abstract : Surface swell over the continental Shelf generates a sheet of oscillatory shear flow at the base of the water column, the continental Shelf Wave bottom boundary layer. The short periods of surface swell sharply limit the thickness of the Wave boundary layer, confining it to a thin region below an oscillatory, but essentially irrotational, core. For a wide range of Shelf conditions, the vertical extent of the Wave boundary layer does not exceed 2.5 cm and is commonly less. The extreme narrowness of this boundary layer is responsible for high levels of bottom stress and turbulent dissipation. Even in relatively mild sea states, the Wave induced bottom shear stress can be sufficient to initiate sediment motion. The Wave bottom boundary layer plays an important role in the processes of sediment entrainment and transport on the continental margins. This thesis documents the development, testing, and field use of a new instrument, the BASS Rake, designed to measure velocity profiles in the Wave boundary layer. The mechanical design supports multiple measurement levels with millimeter vertical spacing. The mechanical design is integrated with an electronic interface designed to permit flexible acquisition of a suite of horizontal and vertical velocity measurements without sacrificing the electronic characteristics necessary for high measurement accuracy. The effects of velocity averaging over the sample volume are calculated with a model of acoustic propagation in a scattering medium appropriate to the scales of a single differential travel time axis. A simpler parametric model of the averaging process is then developed and used to specify the transducer characteristics necessary to image the Wave boundary layer on the continental Shelf.
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Preliminary tow tank and flume tests of a prototype BASS Rake Wave bottom boundary layer sensor
OCEANS 96 MTS IEEE Conference Proceedings. The Coastal Ocean - Prospects for the 21st Century, 1996Co-Authors: A.t. Morrison, A J WilliamsAbstract:The BASS Rake is an acoustic travel time current meter designed to make spatially and temporally dense velocity profile measurements in the continental Shelf Wave bottom boundary layer. The vertical extent of the WBBL is typically one to several centimeters, varying with water depth and Wave conditions. The thinness of the layer is responsible for high levels of bottom shear stress which are important contributors to the sediment entrainment process and which enhance turbulent dissipation of flow energy. The BASS Rake is a modification of BASS, the Benthic Acoustic Stress Sensor, using a new geometry to image flow in the WBBL. An analysis of the flow distortion due to the sensor is presented suggesting some dependence of the gain on flow speed. Tow tank tests demonstrate the suggested dependence and are used to calibrate the sensor. In flume tests, the horizontal velocity vector is measured at 0.5 cm, 2.4 cm, and 5.0 cm above a sand bottom at nominal flow speeds of 10 cm/s, 20 cm/s, and 34 cm/s and a depth of 8.6 cm. The 34 cm/s test included a significant bedload with no observed degradation of sensor performance. Velocity profiles are acquired within a 4 ms window at a 1 Hz rate. The flume measurements are compared to concurrent measurements made with an LDV.
Ross Vennell - One of the best experts on this subject based on the ideXlab platform.
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observation of a fast continental Shelf Wave generated by a storm impacting newfoundland using Wavelet and cross Wavelet analyses
Journal of Physical Oceanography, 2010Co-Authors: Severin Thiebaut, Ross VennellAbstract:Abstract Wavelet and cross-Wavelet power spectra of sea level records from tide gauges along the Atlantic coast of Canada showed a low-frequency barotropic response after Hurricane Florence crossed the Newfoundland Shelf in September 2006. In comparison with two other storms, the results showed that Florence was the only one that excited a propagating sea level disturbance with a period range similar to the passage time of the storm over the Shelf (26–30 h) and phase shifts consistent with a barotropic continental Shelf Wave (CSW). The high amplitude of the oscillations generated by Florence along the shore diminished from approximately 45 to 12 cm as the CSW propagated from the south coast of Newfoundland to the southern Nova Scotia seaboard. This paper presents the first direct measurement of a remarkably high alongshore group speed (11.4 ± 5.9 m s−1), in the manner of free-barotropic CSW, by examination of sea level Wavelet power spectra at different locations. Furthermore, using cross-Wavelet analysis...
Dake Chen - One of the best experts on this subject based on the ideXlab platform.
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hurricane sandy storm surges observed by hy 2a satellite altimetry and tide gauges
Journal of Geophysical Research, 2014Co-Authors: Nan Chen, Guoqi Han, Jingsong Yang, Dake ChenAbstract:Hurricane Sandy made landfall to the northeast of Atlantic City, New Jersey at 23:30 UTC on 29 October 2012 and caused large storm surges and devastating flooding along the New Jersey and New York coasts. Here we combine sea surface height measurements from the HaiYang-2A (HY-2A) satellite altimeter with coastal tide-gauge data to study the features of the Hurricane Sandy storm surges. The HY-2A altimeter captured the cross-Shelf profile of surge at the time of Sandy's peak surge, with a surge magnitude of about 1.83 m at the coast and a cross-Shelf decaying scale of 68 km. The altimetric surge magnitude agrees approximately with tide-gauge estimate of 1.73 m at nearby Montauk. Further analysis suggests that continental Shelf Waves were generated during the passage of Sandy. The continental Shelf Wave observed by altimetry has a propagating speed of 6.5 m/s. The post landfall free Shelf Wave at Atlantic City observed by tide gauges has a propagating phase speed of 6.8 m/s and cross-Shelf e-folding scale of 75 km. In contrast, the post landfall sea level oscillation at Montauk is not associated with a continental Shelf Wave. The study indicates that satellite altimetry is capable of observing and useful for understanding features of storm surges, complementing existing coastal tide gauges.