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No description available.

The relationship between microwave radar and optical video imaging of the nearshore region is studied. The remotely sensed data were used to estimate the longshore currents and the surf zone width. Doppler radar relies on small scale surface roughness that scatters the incident electromagnetic radiation so that velocities are obtained from the Doppler shift of the backscattered radiation. Video relies on texture and contrast of scattered sunlight from the sea surface, and velocity estimates are determined using Particle Imaging Velocimetry (PIV). This study compares video PIV-derived and Doppler radar surface velocities over a 1 km alongshore by 0.5 km cross-shore area in the surf zone of a natural beach. The two surface velocity estimates are strongly correlated (R2 ≥ 0:79) over much of the surf zone. Estimates differ at the outer edge of the surf where strong breaking is prevalent, with radar estimated velocities as much as 50% below the video estimates. Both systems observe a strong eddy-like mean flow pattern over 200 m section of coastline with the mean alongshore current changing direction at about the mid surf zone. The radar and PIV velocities at particular locations in the surf zone track each other well over a 6 hour period, showing strong modulations in the mean alongshore flow occurring on 10-20 minute time intervals. The offshore region in the absence of sufficiently strong wind is sometimes barely visible, while the surf zone always appears very bright in radar backscatter images due to persistent surface roughness produced by breaking waves. The backscatter and coherence radar images were used in conjunction with edge detection filters to estimate the surf zone width from radar data. The surf zone width from video data is calculated using the time-stacking techniques. The comparison of surf zone width over 6 hours showed the rms difference of 8.8 m close to the radar location while the radar had the tendency to overestimate the distance for most of the run. The correlation of two measurements was high at 0.89. At locations farther than 600 m away from the radar the surf zone width rms differences were higher, up to 24 m, while correlation remained high. The differences are attributed to the estimate of the shoreline in radar images due to different scattering properties of wet and dry sand. The good spatial and temporal agreement between the two remote measurement techniques which rely on very different mechanisms, suggests that both are reasonably approximating the nearshore processes.

The dielectric properties and emissivity of several types of sea ice were studied to improve upon the currently available algorithms for intepreting polar radiometric imagery from the SSM/I sensor. Laboratory studies indicated that the relative dielectric constant of new sea ice, as measured with a spectral C-Band radiometer, is approximately 12. This value represents the early stages of ice formation, and decreases rapidly with ice growth to approach the accepted value of 3.2 for first year ice. Atmospheric effects on satellite based passive microwave data were also examined with regard to the 19, 22, 37, and 85 GHz channels of the SSM/I system. The atmospheric vapor and cloud liquid water attenuation was empirically modeled with respect to frequency and atmospheric temperature. The mean atmospheric temperature was empirically linked to surface temperature through an exponential relationship. The surface emissivity was then modelled as a function of surface type via a mixing formalism, where the emissivity of open water depends on surface wind-speed. With the significant environmental variables parameterized, two algorithms for analysis of polar SSM/I data were developed. The first is a simple modification that adds the capability of determining ice temperature to an existing algorithm. The second is a weather correcting algorithm significantly more complex than those currently in use for the lower three frequencies of the Special Sensor Microwave Imager (SSM/I). The uncertainty of the six products due to measurement noise was estimated at 5% for surface parameters and 10% for atmospheric variables. The atmospheric vapor and cloud liquid water estimates are used to convert the raw 85 GHz brightness temperatures to surface brightness temperature estimates, producing a significantly enhanced ice edge.

No description available.

No description available.

<p> The Coastal and Marine Ecological Classification Standard (CMECS) provides a comprehensive framework of common terminology for organizing physical, chemical, biological, and geological information about marine ecosystems. Federally endorsed as a dynamic content standard, all federally funded data must be compliant by 2018; however, applying CMECS to deep sea datasets and underwater video have not been extensively examined. The presented research demonstrates the extent to which CMECS can be applied to deep sea benthic habitats, assesses the feasibility of applying CMECS to remotely operated vehicle (ROV) video data in near-real-time, and establishes best practices for mapping environmental aspects and observed deep sea habitats as viewed by the ROV&rsquo;s forward-facing camera. All data were collected during 2014 in the Northern Gulf of Mexico by the National Oceanic and Atmospheric Administration&rsquo;s (NOAA) ROV <i> Deep Discoverer</i> and ship <i>Okeanos Explorer.</i></p>

A method is developed for thermodynamic and kinematic analysis by partitioning boundary layer data by parcel vertical velocity and the conservative forms of temperature and moisture using a Lagrangian parcel approach. Large Eddy Simulation (LES) derived data fields were used to develop the partitioning method. The LES model provides sufficiently dense and thermodynamically consistent data, which are not yet available from observational datasets. LES Model data fields are three velocity components, potential temperature, total water mixing ratio, cloud liquid water, turbulent kinetic energy (TKE), and buoyancy. The procedure calculates vertical mixing, vertical transports, and the joint frequency histograms of the turbulent data fields with respect to potential temperature and total water mixing ratio, with a Lagrangian partitioning into strong rising, strong sinking, and weakly moving subsets. / An analysis of boundary layer thermodynamics using datasets from the large eddy simulation (LES) model is used to test the partitioning and analysis method. Observed datasets from the Frontal Air Sea Interaction Experiment (FASINEX) are used for comparative analysis of marine boundary layers and LES results. Results indicate the method is useful in further understanding the diurnal boundary layer entrainment hysteresis cycle, vertical transport, and similar features which develop from the non-Gaussian properties of turbulent boundary layer data. Potential applications of these results in boundary layer modeling are discussed. / Source: Dissertation Abstracts International, Volume: 55-01, Section: B, page: 0131. / Major Professor: Eric A. Smith. / Thesis (Ph.D.)--The Florida State University, 1993.

Meltwater accumulated on the Greenland Ice Sheet drains to glacier beds, discharging into fjords hundreds of meters below sea level. The injection of meltwater at depth generates an upwelling plume that entrains warm ocean water as it rises along the terminus, increasing submarine melt and driving a fjord-scale exchange flow. However, due to sparse ocean-glacier observations, we lack a process understanding of how plumes control fjord circulation and submarine melt. Combining numerical modeling, theory, and observations, this dissertation investigates near-glacier plume dynamics, the influence of glacier depth on plume structure and submarine melt, and the role of fjord-glacier geometry on circulation in tidewater glacier fjords. In Chapter II, I use buoyant plume theory and a nonhydrostatic, three-dimensional ocean–ice model to investigate the sensitivity of plume dynamics to subglacial discharge, turbulent diffusivity, and conduit geometry. Large discharges result in plumes with positive temperature and salinity anomalies in the upper water column. Fjord circulation is sensitive to conduit geometry; distributed subglacial discharge results in a stronger return flow of warm water toward the terminus. In Chapter III, I use buoyant plume theory, initialized with realistic ranges of subglacial discharge, glacier depth, and ocean stratification, to investigate how plume structure and submarine melt vary during summer months in 12 Greenland fjords. Grounding line depth is a primary control on plume-induced submarine melt: deep glaciers produce warm, salty subsurface plumes that undercut termini, and shallow glaciers produce cold, fresh surface-confined plumes that can overcut. Finally, in Chapter IV, I use regional-scale numerical ocean simulations to systematically evaluate how fjord circulation forced by subglacial plumes, tides, and wind stress depends on fjord width, glacier depth, and sill height. Glaciers grounded below sill depth can draw shelf waters over a shallow sill and into fjord basins with seasonal subglacial discharge; this process is independent of external shelf forcing. These results underscore the first-order effect that subglacial discharge and fjord-glacier geometry have in controlling fjord circulation and, thus, ocean heat flux to the ice. This dissertation includes previously published and co-authored material.

Lignin and pigment biomarkers were analyzed in sediments of the Louisiana Continental margin along two major depositional pathways (along shore and offshore to the Mississippi Canyon) from SW Pass in July 2003. Results from surface sediments indicate resuspension and reworking of shelf sediments in shallow waters and mobile mud deposits were more effective at oxidizing terrestrial material west of SW Pass than to the southwest. Barataria Bay material may be a contributing source of sedimentary organic matter in shallow shelf areas bordering the Bay and is thus potentially important in carbon cycling. Hurricane Ivan mobilized sedimentary organic carbon (SOC) offshore and homogenized terrestrial sediment parameters and gradients Results from box-core profiles showed preferential loss of more labile pigment SOC during burial and diagenesis. Low burial efficiencies along the western transect for bulk and labile biomarkers indicate mobile muds were efficient in the remineralization of labile organic matter. Lignin appeared to be a useful paleo indicator in dynamic RioMar environments likely reflecting source input rather than diagenesis after initial deposition. Pigment concentrations and ratios may not be useful in a quantitative sense for paleo-reconstructions within dynamic RioMar regions. Oxic degradation of labile material in the Surface Active Zone was highly efficient, effecting the quantity and quality of material buried below Lignin profiles in age-dated cores (210Pb geochronology) indicate artificial reservoir retention as a major control on organic carbon quantity and quality post-1950 reaching the margin, whereas, pre-1950 sediments may reflect soil erosion due to land-clearing and farming practices. Terrestrially derived organic carbon signatures were mixed angiosperms over the last 150 yrs. Stochastic events such as hurricanes and large river floods have a measurable, albeit ephemeral, effect on the shelf SOC record. Land-use changes in the MR basin have likely affected carbon cycling and SOC burial on the LCM over a large spatial extent as observed by similar trends in cores from across and along margin. Finally, sediment focusing seems to be a very important aspect that can complicate down-core interpretation when trying to make comparisons over wide spatial scale / acase@tulane.edu