ALBERT

Description: Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 2645-2662, doi:10.1175/JPO-D-15-0191.1.

Description: The occurrence, drivers, and implications of small-scale O(2–5) km diameter coherent vortices, referred to as submesoscale eddies, over the inner shelf south of Martha’s Vineyard, Massachusetts, are examined using high-frequency (HF), radar-based, high-resolution (400 m) observations of surface currents. Within the 300 km2 study area, eddies occurred at rates of 1 and 4 day−1 in winter and summer, respectively. Most were less than 5 h in duration, smaller than 4 km in diameter, and rotated less than once over their lifespan; 60% of the eddies formed along the eastern edge of study area, adjacent to Wasque Shoal, and moved westward into the interior, often with relative vorticity greater than f. Eddy generation was linked to vortex stretching on the ebb and flood tide as well as the interaction of the spatially variable tide and the wind-driven currents; however, these features had complex patterns of surface divergence and stretching. Eddies located away from Wasque Shoal were related to the movement of wind-driven surface currents, as wind direction controlled where eddies formed as well as density effects. Using an analysis of particles advected within the radar-based surface currents, the observed eddies were found to be generally leaky, losing 60%–80% of particles over their lifespan, but still more retentive than the background flow. As a result, the combined translation and rotational effects of the observed eddies were an important source of lateral exchange for surface waters over the inner shelf.

Description: The HF radar data utilized here were obtained using internal funding from the Woods Hole Oceanographic Institution. The analysis was supported by NSF OCE Grant 1332646.

Description: 2017-02-19

Description: Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 2201-2218, doi:10.1175/JPO-D-16-0020.1.

Description: This paper aims to test the validity, utility, and limitations of the lateral eddy diffusivity concept in a coastal environment through analyzing data from coupled drifter and dye releases within the footprint of a high-resolution (800 m) high-frequency radar south of Martha’s Vineyard, Massachusetts. Specifically, this study investigates how well a combination of radar-based velocities and drifter-derived diffusivities can reproduce observed dye spreading over an 8-h time interval. A drifter-based estimate of an anisotropic diffusivity tensor is used to parameterize small-scale motions that are unresolved and underresolved by the radar system. This leads to a significant improvement in the ability of the radar to reproduce the observed dye spreading.

Description: IR, AK, and SL were supported by the NSF OCE Grant 1332646. IR was also supported by NASA Grant NNX14AH29G.

Description: 2016-12-29

Description: The landscape of applied ocean technology is rapidly changing with forces of innovation emerging from basic ocean science research methodologies as well as onshore high tech sectors. There is a critical need for ocean-related industries to continue to modernize via the adoption of state-of-the-art practices to advance rapidly changing industry objectives, maintain competitiveness, and be careful stewards of the ocean as a common resource. These objectives are of national importance for the dynamic ocean energy sector, and a mechanism by which new and promising technologies can be validated and adopted in an open and benchmarked process is needed. POWER-US seeks to develop Ocean Test Beds as research and development infrastructure capable of driving innovative observations, modeling, and monitoring of the physical, biological, and use characteristics present in offshore wind energy installation areas.

Description: AK acknowledges internal support from the Woods Hole Oceanographic Institution via the Houghton Foundation Award.

Description: Moored hydrographic and velocity observations along with vessel surveys of the Outer Cape Coastal Current off Nauset, MA.

Description: This data was used in the preparation of a manuscript "Drivers of Spring and Summer Variability in the Coastal Ocean Offshore of Cape Cod, MA." submitted for publication to the Journal of Geophysical Research. The work describes the drivers of spring and summer variability within the coastal ocean east of Cape Cod, Massachusetts, a critical link between the Gulf of Maine and Mid-Atlantic Bight, are investigated using two years of shipboard and moored hydrographic and velocity observations from 2010 and 2011. Converted to netCDF via MATLAB by A. Kirincich

Description: The observations used in this study were supported by NOAA SeaGrant #NA10OAR4170083 and internal funding from the Woods Hole Oceanographic Institution. Analysis was supported via internal funding from the Woods Hole Oceanographic Institution

Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 1789–1805, doi:10.1002/2015JC011252.

Description: The drivers of spring and summer variability within the coastal ocean east of Cape Cod, Massachusetts, a critical link between the Gulf of Maine and Mid-Atlantic Bight, are investigated using 2 years of shipboard and moored hydrographic and velocity observations from 2010 and 2011. The observations reveal sharp differences in the spring transition and along-shelf circulation due to variable freshwater and meteorological forcing, along with along-shelf pressure gradients. The role of the along-shelf pressure gradient is inferred using in situ observations of turbulent momentum flux, or Reynolds stresses, estimated from the ADCP-based velocities using recently developed methods and an inversion of the along-shelf momentum balance. During spring, the locally relevant along-shelf pressure gradient contains a sizable component that is not coupled to the along-shelf winds and often opposes the regional sea level gradient. Together with the winds, local pressure gradients dominate along-shelf transport variability during spring, while density-driven geostrophic flows appear to match the contribution of the local winds during summer. These results suggest that local effects along the Outer Cape have the potential to cause significant changes in exchange between the basins.

Description: NOAA. Grant Number: NA10OAR4170083; Woods Hole Oceanographic Institution

Description: 2016-09-19

Description: The WHOI HF radar system, as operated during the 2011-2012 time period, consisted of 3 individual HF radars located along the south coast of the island of Martha's Vineyard, MA at infrastructure of the Martha's Vineyard Coastal Observatory (MVCO). The system had the technical goal of measuring currents at scales approaching 400 m within a 20 km by 20 km domain south of Martha's Vineyard. The system is composed of three closely spaced sites with SeaSonde-type DF instruments running at operating frequencies near 25 MHz. Two of the three sites are located on land, with one placed at the MVCO Shore Meteorological Station (METS) and the second approximately 10 km to the west at the Long Point Wildlife Refuge (LPWR). The third site is located on the MVCO Air-Sea Interaction Tower (ASIT), approximately 4 km offshore and south of the island. To achieve the highest possible radial resolution (420 m) given the 350 kHz of bandwidth available at 25 MHz, all sites run at common frequencies using GPS- based timing to separate the transmissions from each site. Given the small spatial domain that can be adequately sampled at low geometric error with this configuration, as well as potential for interactions between the instruments at the land and tower sites, all sites transmit at low power (1-2 W, less than 3% of typical systems). The MVCO HFRs were configured to maximize the spatial and temporal independence of the observations. Spectral estimates of the observed Doppler-shifted velocities are collected in bursts of 1028 non-overlapping frequency sweeps with a sweep rate of 2 Hz for finer-resolution Doppler velocities than is typical for 25-MHz systems without interpolation. A maximum of three, but normally two, successive spectral estimates are averaged to create the necessary ensemble estimate every 15 min. Direction finding and azimuthal averaging into 5deg bands is performed on each ensemble and, for data processed using the standard software suite, successive radial velocity estimates are time averaged into 60-min averages every 30 min. No interpolation is used to smooth the fields or fill in radial gaps, but, as in previous works, outliers are removed before computing vector velocities. Given the dense spacing of the radial grid points, the vector averaging is performed using a 400-m grid with grid points starting approximately 600 m offshore and an averaging radius equal to the grid width. These alternative methods were used to achieve finer-resolution velocity estimates having greater spatial independence at the potential expense of increased noise. For the datasets used here, a number of steps were taken to ensure that the radial velocity estimates were of the highest quality possible. The first-order region limits utilized for the analysis were optimized for the conditions present south of Martha's Vineyard. Measured antenna patterns were obtained for each site and utilized in the DF algorithm to estimate radial currents over water. Finally, the spatial structure of the M2 tidal ellipses for the entire domain, estimated from the vector velocity time series at each grid point using T_Tide (Pawlowicz et al. 2002), were analyzed for patterns of unrealistic ellipse inclination (orientation) emanating from a particular site, which serve as an indication of potential bearing-related errors. The measured beam patterns were adjusted by smoothing and/or interpolation, similar to that described by Cosoli et al. (2010) and de Paolo and Terrill (2007), to minimize errors identified. The spatial extent of the vector velocities was limited by theoretical Geometrical Dilution of Precision (GDOP) values less than 1.75. An error estimate for the East, North, and total (norm) of the vector velocity components is given. Converted to netCDF via MATLAB by A. Kirincich

Description: This data was collected by Kirincich as part of ongoing studies examining the spatial variability of the mechanisms and process that lead to the exchange of water masses across the inner part of the continental shelf. The data consists of estimates of the near-surface horizontal (East and North) ocean currents made via High Frequency (HF) radar-based remote sensing of the ocean backscatter spectrum. The dataset spans an 18-month period from February 2011 to August 2012. The effective measurement depth of the WHOI HF radars is 0.5 m below the ocean surface.

Description: The observations used in this study were supported by NSF OCE Grant #1332626 and internal funding from the Woods Hole Oceanographic Institution.

Description: This zipped content contains Lidar raw data: Raw 10-minute files of 1 Hz data files from 53-200m amsl from April-June 2018.

Description: This zipped content contains Lidar raw data: Raw 10-minute files of 1 Hz data files from 53-200m amsl from October-December 2018.