Summary

Description

This dataset contains an ESRI Grid representing the rugosity of the bathymetry of the north shore of St. Croix, US Virgin Islands and south west shore (La Parguera) of Puerto Rico, based on a 10 m bathymetric grid. Rugosity is defined as the ratio of surface area to planar area and is used as a measure of benthic terrain complexity or "roughness". Rugosity values near 1 represent flat, smooth terrain, while higher values reflect increasing rugosity or terrain roughness. For rugosity grid interpretation, is recommended that the grid be reclassified according to standard deviation divisions.NOAA's NOS/NCCOS/CCMA Biogeography Team, in collaboration with NOAA vessel Nancy Foster and territory, federal, and private sector partners, acquired multibeam bathymetry data in the US Virgin Islands from 3/21/06 to 4/2/06. Data was acquired with a hull-mounted Kongsberg Simrad EM 1002 multibeam echosounder (95 kHz) and processed by a NOAA contractor using CARIS HIPS v6.0 software. Data has all correctors applied (attitude, sound velocity) and has been reduced to mean lower low water (MLLW) using final approved tides and zoning from NOAA COOPS. Data is in UTM zone 20 north, datum NAD83. The processed CARIS data was used to generate a CARIS BASE surface based on swath angle. An ASCII XYZ file was exported from the BASE surface and opened in ESRI ArcMap 9.1 as an XY event. Then the ArcToolbox conversion tool 'Feature to Raster' was used to generate an ESRI Grid of bathymetry. The Benthic Terrain Modeller (BTM) tool, a collection of ArcGIS terrain visualization tools developed by the Oregon State University (OSU) Department of Geosciences and the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center, was used to calculate the rugosity of that bathymetric grid. More information on the specific algorithms used can be found in the BTM's documentation.The project was conducted to meet IHO Order 1 and 2 accuracy standards, dependant on the project area and depth. All users should individually evaluate the suitability of this data according to their own needs and standards.