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U.S. Geological Survey Sea Floor Stress and Sediment Mobility Database

Middle Atlantic Bight

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Map showing Middle Atlantic Bight
Figure 2. Map showing the bathymetry of the Middle Atlantic Bight and regional physiographic features. Characterizations of bottom shear stress and sea floor mobility in this database extend offshore to approximately the 120-m isobath.

The Middle Atlantic Bight region extends from Nantucket Shoals off southern New England southward to Cape Lookout off North Caroline (Fig. 2).

Spatially and temporally resolved estimates of bottom shear stress are calculated for seasonal and annual time periods. Seasons are defined as Winter (December-February), Spring (March-May), Summer (June-August), and Fall (September-November).

Specifications for stress and mobility time series:

  • Spatial Resolution: Approximately 5 km.
  • Time Period: May 2010 to May 2011.
  • Temporal Resolution: Hourly.

Data sets used to compute the bottom stress and sediment mobility time series:

  • Currents: Experimental System for Predicting Shelf and Slope Optics (ESPreSSO) model, which uses the Regional Ocean Modeling System (ROMS). The ESPreSSO domain covers the Middle Atlantic Bight continental shelf from Cape Cod southward to Cape Hatteras. Developed at Rutgers University (http://www.myroms.org/espresso). Contact: Model run by Dr. John Wilkin, Rutgers Ocean Modeling Group.
  • Waves: Simulating WAves Nearshore (SWAN) model applied to the western North Atlantic. Contact: Model run by Dr. P. Soupy Dalyander, U.S. Geological Survey St. Petersburg Coastal and Marine Science Center
  • Sediment Texture Data: USGS East-Coast Sediment Texture database (Poppe and others, 2005).

Complete details on the procedure used to create the data files may be found in the associated metadata (links in Table 1).

Note: Additional analysis of bottom shear stress and sediment mobility for this domain may be found in: Dalyander, P. S., Butman, B., Sherwood, C.R., Signell, R.P., Wilkin, J.L., 2012, Characterizing Wave- and Current- Induced Bottom Shear Stress: U.S. Middle Atlantic Bight. Continental Shelf Research (52), p.73-86. Online at http://www.sciencedirect.com/science/article/pii/S0278434312002889.

Table 1. Statistics of sea floor wave-current stress and sediment mobility in Arc polygon and point shapefile format for the Middle Atlantic Bight from model output. Stress statistics are determined for the entire model grid, whereas mobility statistics are determined only at locations where sediment texture data are available. See metadata files for details of the calculations. Click on zip file to download.

Data Layer Name
Preview
Explanation File Type
Metadata
Files

Median of Bottom Shear Stress

Preview (Yearly Value)

The value of bottom shear stress exceeded 50% of the time. Shapefile - polygon

View Metadata
zip

Interpercentile Range of Bottom Shear Stress

Preview (Yearly Value)

Half the difference between the 84th and 16th percentile. A measure of variability, equivalent to the standard deviation in a normal distribution. Shapefile - polygon

View Metadata
zip

95th Percentile of Bottom Shear Stress

Preview (Yearly Value)

Value of bottom shear stress exceeded 5% of the time. A measure of the largest stresses. Shapefile - polygon

View Metadata
zip

Bed Mobility Percentage

Preview (Yearly Value)

Percentage of time the critical stress is exceeded (determined for locations with sediment texture data). A measure of the extent of bed mobility. Shapefile - point

View Metadata
zip

Bed Mobility Recurrence Interval

(version 1.1)

Preview (Yearly Value)

Time between mobility events (determined for locations with sediment texture data). A measure of the of frequency of mobility events. Shapefile - point

View Metadata
zip
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