scholarly journals The Occurrence, Drivers, and Implications of Submesoscale Eddies on the Martha’s Vineyard Inner Shelf

2016 ◽  
Vol 46 (9) ◽  
pp. 2645-2662 ◽  
Author(s):  
Anthony Kirincich
Keyword(s):  
Relative Vorticity ◽  
Hf Radar ◽  
Small Scale ◽  
Surface Currents ◽  
Inner Shelf ◽  
Martha's Vineyard ◽  
Martha’S Vineyard ◽  
Eddy Generation ◽  
Wind Driven Currents ◽  
Eastern Edge

AbstractThe 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.

scholarly journals Interoperability of SeaSondes and Wellen Radars in Mapping Radial Surface Currents

2013 ◽  
Vol 30 (11) ◽  
pp. 2662-2675 ◽  
Author(s):  
J. Martinez-Pedraja ◽  
L. K. Shay ◽  
B. K. Haus ◽  
C. Whelan
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Hf Radar ◽  
Small Scale ◽  
Surface Currents ◽  
Florida Current ◽  
Current Profiler ◽  
Florida Straits ◽  
Subsurface Current ◽  
Geometric Dilution Of Precision ◽  
Good Agreement

Abstract A dual-station high-frequency (HF) Wellen Radar (WERA) transmitting at 16 MHz has observed near-real-time surface currents over an approximate range of 100 km across the Florida Straits since July 2004. During a 10-day period in April 2005 (15–25 April), a pair of 12.6-MHz SeaSondes (SS) were deployed south of the WERAs sites by NOAA's Center for Operational Oceanographic Products and Services (CO-OPS). The resulting SS grid overlapped the southern portion of the WERA domain. During the same period of time, a bottom-mounted acoustic Doppler current profiler (ADCP) acquired subsurface current measurements within these HF radar grids starting at 14 m below the surface in water of 86-m depth. The interoperability of beam-forming (WERA) and direction-finding (SS) HF radar technologies was examined. Comparisons of radial and vector currents for an 8-day concurrent time series suggested good agreement in current direction over both domains, where the surface currents' magnitudes were a maximum of 1.2 m s−1. In the core of the radar domains consisting of 108 cells, hourly vector currents were obtained by combining WERA and SS radials. Generally, this can be done in a relatively straightforward manner, considering the geometric dilution of precision (GDOP). A second key issue is downscaling the SS measurements from a 3-km grid to a 1.1-km grid to match the WERA output. This enhanced grid spacing is important along the western flank of the Florida Current, where energetic, small-scale surface features have been observed.

scholarly journals The Spatial Structure of Tidal and Mean Circulation over the Inner Shelf South of Martha's Vineyard, Massachusetts

2013 ◽  
Vol 43 (9) ◽  
pp. 1940-1958 ◽  
Author(s):  
Anthony R. Kirincich ◽  
Steven J. Lentz ◽  
J. Thomas Farrar ◽  
Neil K. Ganju
Keyword(s):  
Heat Flux ◽  
Spatial Structure ◽  
Spatial Scales ◽  
Local Heat ◽  
Recirculation Region ◽  
Flux Divergence ◽  
Inner Shelf ◽  
Martha's Vineyard ◽  
Martha’S Vineyard ◽  
Mean Circulation

Abstract The spatial structure of the tidal and background circulation over the inner shelf south of Martha's Vineyard, Massachusetts, was investigated using observations from a high-resolution, high-frequency coastal radar system, paired with satellite SSTs and in situ ADCP velocities. Maximum tidal velocities for the dominant semidiurnal constituent increased from 5 to 35 cm s−1 over the 20-km-wide domain with phase variations up to 60°. A northeastward jet along the eastern edge and a recirculation region inshore dominated the annually averaged surface currents, along with a separate along-shelf jet offshore. Owing in part to this variable circulation, the spatial structure of seasonal SST anomalies had implications for the local heat balance. Cooling owing to the advective heat flux divergence was large enough to offset more than half of the seasonal heat gain owing to surface heat flux. Tidal stresses were the largest terms in the mean along- and across-shelf momentum equations in the area of the recirculation, with residual wind stress and the Coriolis term dominating to the west and south, respectively. The recirculation was strongest in summer, with mean winds and tidal stresses accounting for much of the differences between summer and winter mean circulation. Despite the complex bathymetry and short along-shelf spatial scales, a simple model of tidal rectification was able to recreate the features of the northeastward jet and match an estimate of the across-shelf structure of sea surface height inferred from the residual of the momentum analysis.

Vernacular American Landscape: Methodists, Camp Meetings, and Social Respectability

1994 ◽  
Vol 4 (2) ◽  
pp. 165-191 ◽  
Author(s):  
Roger Robins
Keyword(s):  
Cape Cod ◽  
Church Members ◽  
White Mountains ◽  
Martha's Vineyard ◽  
Home State ◽  
American Landscape ◽  
Camp Meetings ◽  
Martha’S Vineyard ◽  
Religious Landscape ◽  
The Church

In 1822, from his Conway home in the shadow of New Hampshire's White Mountains, one Dr. Porter surveyed the nation's religious landscape and prophesied, “in half a century there will be no Pagans, Jews, Mohammedans, Unitarians or Methodists.” The prophecy proved false on all counts, but it was most glaringly false in the case of the Methodists. In less than a decade, Porter's home state became the eighth to elect a Methodist governor. Should Porter have fled south into Massachusetts to escape the rising Methodist tide, he would only have been buying time. True, the citizens of Provincetown, Massachusetts, had, in 1795, razed a Methodist meetinghouse and tarred and feathered a Methodist in effigy. By 1851, however, the Methodists boasted a swelling Cape Cod membership, a majority of the church members on Martha's Vineyard, and a governor in the Massachusetts statehouse.

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