3 research outputs found
Recommended from our members
The Inner-Shelf Dynamics Experiment
17 USC 105 interim-entered record; under review.The article of record as published may be found at http://dx.doi.org/10.1175/BAMS-D-19-0281.1The inner shelf, the transition zone between the surfzone and the midshelf, is a dynamically complex region with the evolution of circulation and stratification driven by multiple physical processes. Cross-shelf exchange through the inner shelf has important implications for coastal water quality, ecological connectivity, and lateral movement of sediment and heat. The Inner-Shelf Dynamics Experiment (ISDE) was an intensive, coordinated, multi-institution field experiment from September–October 2017, conducted from the midshelf, through the inner shelf, and into the surfzone near Point Sal, California. Satellite, airborne, shore- and ship-based remote sensing, in-water moorings and ship-based sampling, and numerical ocean circulation models forced by winds, waves, and tides were used to investigate the dynamics governing the circulation and transport in the inner shelf and the role of coastline variability on regional circulation dynamics. Here, the following physical processes are highlighted: internal wave dynamics from the midshelf to the inner shelf; flow separation and eddy shedding off Point Sal; offshore ejection of surfzone waters from rip currents; and wind-driven subtidal circulation dynamics. The extensive dataset from ISDE allows for unprecedented investigations into the role of physical processes in creating spatial heterogeneity, and nonlinear interactions between various inner-shelf physical processes. Overall, the highly spatially and temporally resolved oceanographic measurements and numerical simulations of ISDE provide a central framework for studies exploring this complex and fascinating region of the ocean.U.S. Office of Naval Research (ONR)ONR Departmental Research Initiative (DRI)Inner-Shelf Dynamics Experiment (ISDE
Comparison between the wintertime and summertime dynamics of the Misa River estuary
The Misa River on the Italian Adriatic coast is typical of the rivers that drain the Apennine Mountain range. The focus of this study, conducted in the late summer of 2013 and mid-winter of 2014, was to contrast the general wintertime-summertime dynamics in the Misa River estuarine system rather than investigate specific dynamical features (e.g. offshore sediment transport, channel seiche, and flocculation mechanisms). Summertime conditions of the Misa River estuary are characterized by low freshwater discharge and net sediment deposition whereas, in the wintertime, the Misa River and estuary is characterized by high episodic freshwater discharge and net erosion and sediment export. Major observed differences between wintertime-summertime dynamics in the Misa River and estuary are a result of seasonal-scale differences in regional precipitation and forcing conditions driven largely by the duration and intensity of prevailing wind patterns that frequently change direction in summertime while keep almost constant directions for much longer periods in wintertime, thus generating major sea storms. Sediment deposition was observed in the final reach of the Misa River and estuary in the summertime. However, in the wintertime, large flood events led to sediment erosion and export in the final reach of the Misa River and estuary that, in conjunction with storm-wave-induced mud transport, led to sediment deposition at the river entrance and in the adjacent nearshore region. The seasonal cyclic pattern of erosion and deposition was confirmed with bathymetric surveys of the final reach of the estuarine region. A critical component for the balance between summertime deposition and wintertime erosion was the presence of an underlying mat of organic deposits that limited the availability of sediments for erosion in winter, when massive debris transport occurs. Further, suspended cohesive sediments flocs were subjected to smaller hydrodynamic stresses in the summertime favoring deposition within the estuary. Conversely, during wintertime storms, flocs were subjected to larger hydrodynamic stresses favoring breakup into smaller flocs and deposition outside the estuary