Shrnutí

Popis

This data represents a LiDAR (Light Detection & Ranging) gridded bathymetric surface and a gridded relative seafloor reflectivity surface (incorporated into the las format as intensity) for an area of shallow seabed: 1. Surrounding St. Thomas and St. John (STT/STJ): 3m x 3m grid 2. Mouth of Salt River Bay (SARI) in St. Croix: 5m x 5m grid 3. Buck Island Reef National Monument (BUIS) in St. Croix: 3m x 3m grid Fugro LADS, in collaboration with NOAA's National Ocean Service (NOS), National Centers for Coastal Ocean Science (NCCOS), Center for Coastal Monitoring and Assessment (CCMA), Biogeography Branch, the University of New Hampshire and the National Park Service, acquired bathymetry, relative seafloor reflectivity and hyperspectral imagery in St. Thomas and St. John on thirteen separate dates between 1/29/2011 to 2/28/2011 and in St. Croix (SARI and BUIS) on 2/21/2011 and 2/22/2011. 1. STT/STJ Hyperspectral data were acquired using a Hyspex VNIR-1600 sensor. Bathymetry and reflectivity data were acquired using a LADS (Laser Airborne Depth Sounder) Mark II Airborne System from altitudes between 1,200 and 2,200ft at ground speeds between 140 and 210 knots. The 900 Hertz Nd: YAG (neodymium-doped yttrium aluminum garnet) laser (1064 nm) acquired 3x3 meter spot spacing and 200% seabed coverage. For STT/STJ, 168.1 square kilometers of LiDAR were collected between 0 m and 40 m in depth. Data was flown for charting. This data met IHO Order 1 standards. 2. SARI Hyperspectral data were acquired using a Hyspex VNIR-1600 sensor. Bathymetry and reflectivity data were acquired using a LADS (Laser Airborne Depth Sounder) Mark II Airborne System from altitudes between 1,200 and 2,200ft at ground speeds between 140 and 175 knots. The 900 Hertz Nd: YAG (neodymium-doped yttrium aluminum garnet) laser (1064 nm) acquired 5x5 meter spot spacing and 200% seabed coverage. For SARI, 1.62 square kilometers of LiDAR were collected between 0 m and 34 m in depth. This data was collected for research, not charting. It was collected using the same acquistion parameters as STT/STJ, but its uncertainties were not quantified. As such, it is not known if this data meets IHO Order 1 standards. 3. BUIS Hyperspectral data were acquired using a Hyspex VNIR-1600 sensor. Bathymetry and reflectivity data were acquired using a LADS (Laser Airborne Depth Sounder) Mark II Airborne System from altitudes between 1,200 and 2,200ft at ground speeds between 140 and 175 knots. The 900 Hertz Nd: YAG (neodymium-doped yttrium aluminum garnet) laser (1064 nm) acquired 3x3 meter spot spacing and 200% seabed coverage. For BUIS, 35.9 square kilometers of LiDAR were collected between 0 m and 49 m in depth. This data was collected for research, not charting. It was collected using the same acquistion parameters as STT/STJ, but its uncertainties were not quantified. As such, it is not known if this data meets IHO Order 1 standards. The data received from NCCOS were in GEOTIFF format for both the lidar and seafloor reflectivity. The NOAA Coastal Services Center converted these two data sets to text format and then combined them into one text file based on x and y. The text file was then converted to las format, where the seafloor reflectivity is represented as intensity. The data's horizontal coordinate system was NAD83 UTM 20 North, and depth values were collected in meters referenced to Mean Lower Low Water (MLLW) depths. Upon receipt of the data, the NOAA Coastal Services Center converted the data to geographic coordinates and ellipsoid heights for data storage and Digital Coast provisioning purposes. Environmental factors such as wind strength and direction, cloud cover, water clarity and depth influenced the area of data acquisition on a daily basis. The data was processed using the LADS Mark II Ground System and data visualization, quality control and final products were created using CARIS HIPS and SIPS and CARIS BASE Editor. All users should individually evaluate the suitability of this data according to their own needs and standards.