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

Quantifying the Impact of Nonlinear Internal Waves on the Marine Atmospheric Surface Layer

2019 IEEE/OES Twelfth Current, Waves and Turbulence Measurement (CWTM)The article of record as published may be found at https://doi.org/10.1109/CWTM43797.2019.8955282In the coastal environment, the oceanic flow over varying bathymetry can displace the isopycnal surfaces and, thus, generate nonlinear internal waves. These high frequency waves can propagate across large distances and over their lifetime significantly influence local currents and turbulence within a coastal region. These waves also create a common phenomenon that is recognized by even a casual observer: smooth, quasilinear bands of water that disrupt the typically rippled sea surface. While NIWs are an important oceanic process and their surface expression has been characterized and discussed for decades, investigators have not linked the presence of internal wave-driven surface roughness to an atmospheric response. Here we use a combination of oceanic and atmospheric measurements, as well as ocean surface visualization, to show that NIWs can alter the flow within the MASL and the subsequent momentum flux across the air-sea interface, at the dominant temporal-spatial scales of the NIWs. Our measurements were collected from the FLIP, which was deployed as part of the Coupled Air Sea Processes and Electromagnetic ducting Research (CASPER) West Coast field campaign. Using a thermistor chain, X band marine radar, upward- and downward-looking ADCP, as well as a visual field camera imaging the ocean surface near FLIP, we were able to identify several NIW events and track individual waves incident to the platform. This information was used to isolate the atmospheric response, as captured by a profile of meteorological flux sensors installed on a mast that was deployed from FLIP's boom. The observed NIW-interactions were found in multiple cases with different MASL conditions and internal wave properties. In the context of CASPER, the surface roughness associated with NIWs represents a persistent, quasi-Lagrangian heterogeneity that may impact the atmospheric gradients, which in turn modulates the index of refraction and the propagation of electromagnetic radiation.Office of Naval ResearchFunding provided by Office of Naval Research N0001418WX01087

The Atmospheric Surface Layer Response to Nonlinear Internal Ocean Waves

Ocean Sciences Meeting 2020Nonlinear internal ocean waves (NIWs) are regular features of the coastal ocean, where the hydrodynamic flow over changing bathymetry perturbs the isopycnal surfaces generating these high frequency waves. At the air-sea interface, these transient features may be characterized by quasilinear bands of smooth or rough ocean surface that propagate in the direction of the underlying NIWs. Theoretically, this roughness heterogeneity is driven by the phase-locked divergence and convergence of the NIW orbital motions. This NIW action modulates surface wavelengths within the capillary and gravity-capillary band, which also hold the majority of the tangential wind stress. Understanding the spatial-temporal distribution of these small-scale surface waves is critical to constraining air-sea coupling, which is significantly complicated in the case of a heterogeneous surface. The impact NIW-driven surface roughness has on the variability and structure of the atmospheric surface layer is unknown. During a Coupled Air Sea Processes and EM ducting Research (CASPER) field campaign, the Research Platform FLIP was deployed for five weeks in a coastal area with a suite of near-surface oceanographic and meteorological measurements, as well as near-field remote sensing of the surface using both radar, infrared, and optical visualization. This confluence of measurement capability from an ideal platform, enabled us to simultaneously identify and track NIWs while characterizing the variance and structure of the kinematic and thermodynamic state on either side of the interface. NIWs were regularly observed from FLIP, with their characteristic surface banding observed nearly every day of the campaign. Our analysis into one case revealed that NIWs exert a distinct and significant impact on the mean wind gradient, as well as the air-sea momentum flux (i.e. wind stress) on both the scale of individual wave fronts and an entire NIW packet. In particular, the MASL flow adjusts instantaneously to the smooth-rough transitions of individual bands, thereby enhancing the wind stress over the surface. Our presentation will focus on summarizing these findings, as well as highlighting additional NIW events observed during the CASPER campaign from FLIP to discern any underlying or general pattern in the nature of NIW-atmosphere interactions

Wide-Area Debris Field and Seabed Characterization of a Deep Ocean Dump Site Surveyed by Autonomous Underwater Vehicles.

Disposal of industrial and hazardous waste in the ocean was a pervasive global practice in the 20th century. Uncertainty in the quantity, location, and contents of dumped materials underscores ongoing risks to marine ecosystems and human health. This study presents an analysis of a wide-area side-scan sonar survey conducted with autonomous underwater vehicles (AUVs) at a dump site in the San Pedro Basin, California. Previous camera surveys located 60 barrels and other debris. Sediment analysis in the region showed varying concentrations of the insecticidal chemical dichlorodiphenyltrichloroethane (DDT), of which an estimated 350-700 t were discarded in the San Pedro Basin between 1947 and 1961. A lack of primary historical documents specifying DDT acid waste disposal methods has contributed to the ambiguity surrounding whether dumping occurred via bulk discharge or containerized units. Barrels and debris observed during previous surveys were used for ground truth classification algorithms based on size and acoustic intensity characteristics. Image and signal processing techniques identified over 74,000 debris targets within the survey region. Statistical, spectral, and machine learning methods characterize seabed variability and classify bottom-type. These analytical techniques combined with AUV capabilities provide a framework for efficient mapping and characterization of uncharted deep-water disposal sites

Factor Xa cleaves SARS-CoV-2 spike protein to block viral entry and infection

The serine protease factor Xa (FXa) is upregulated in COVID-19 patients and functions in the coagulation pathway. Here, Dong et al characterise the basis of its antiviral activity in the context of SARS-CoV-2 pandemic variants