The U.S. Geological Survey (USGS) Coastal and Marine Geology Program in Woods Hole, Massachusetts, is leading an effort to understand the regional sediment dynamics along the coastline of North and South Carolina. The Carolinas Coastal Change Processes (CCCP) Project examines the interactions between oceanographic forcing, geologic conditions, and the resulting changes to topography of the inner shelf, nearshore, and subaerial beach regions. This report provides an overview of an oceanographic field study conducted in February 2010 to investigate processes that control the dynamics of sediment transport at Cape Hatteras, North Carolina.
To investigate processes that control the dynamics of sediment transport at Cape Hatteras, North Carolina, six field activities were conducted in the study area. A camera was mounted on the lighthouse and georeferenced targets were installed to capture images of the surf zone. These images were used to define estimates of along shore ocean current speed. A single high-frequency (48 MHz) Wellen radar (WERA) site was installed on the dunes to estimate wind, wave, and current conditions. Nearshore surveys were conducted to acquire subaqueous bathymetry and subaerial topography. Uranine dye was injected into the surf zone, aerial targets were installed and aerial photographs were taken to help visualize the circulation dynamics at Cape Point. Oceanographic instruments were deployed to collect wave and current data at 11 sites in the nearshore and at three offshore locations. Figure 1 identifies locations of the equipment for the nearshore (sites starting with “N”), offshore (sites starting with “O”), lighthouse, and WERA sites.
During this field study a benthic unattended generator (BUG) was deployed on the south side of the cape close to the nearshore sites by the Naval Research Laboratory (NRL) to test the fuel cell’s ability to generate electrical power in situ. Data from this field study are available to support NRL’s analysis of the BUG data.
This data report presents background information on the impetus for understanding coastal change processes in the nearshore at Cape Hatteras, a description of the field program (including the oceanographic instrumentation used) to collect data, and the data-processing and archival techniques used. This report also provides access to all observational data related to the field study, available in digital form. The edited data are presented in time-series plots for rapid visualization of the dataset, and in data files that are in the Network Common Data Format (NetCDF).
Many thanks to the National Park Service Outer Banks Group for their support and cooperation during the study. John Warner was the chief scientist. We thank the following personnel for their dedication and hard work during the deployment: U.S. Geological Survey (USGS) divers Chuck Worley, Dann Blackwood, Sandy Baldwin, Michael Casso, B.J. Reynolds, and Jordan Sanford; photographer Don Bowers; USGS technician Jonathan Borden; U.S. Army Corps of Engineers LARC personnel Ray Townsend, Jason Pipes, and Mike Forte; Georgia Tech Savannah students Stephanie Smallegan, Adam Sapp, Thomas Gay, and Xiufeng Yang; University of South Carolina technicians and students Jeff Morin and Kumar Nirnimesh; and Virginia Institute of Marine Science student Kate Brodie. Ellyn Montgomery helped oversee and process the time-series data. Christine Sabens and Ellyn Montgomery helped prepare for deployment and recovery. Jonathan Borden helped during preparation and deployment of the physical oceanographic instrumentation. The reviewers provided useful reviews of this report. This research was funded by the USGS Coastal and Marine Geology Program. Mention of trade names does not imply U.S. Government endorsement of commercial products.
The field program included deploying equipment at eleven sites in the nearshore surf zone and at three offshore locations. The nearshore sites consisted of 11 jetted pole mounts with instruments to measure ocean currents, water levels, wave heights, and wave directions. Seven of these instruments were Aquadopp (current profiler utilizing Doppeler technology) 1 Mhz profilers (N1, N2, N3, N6, N8, N11, and N12). Three sites (N4, N5, and N9) were Teledyne RD Instruments (T-RDI) 1200 Khz ADCPs. Site N13 consisted of an acoustic Doppler velocimeter-Triton (ADV) and an acoustic backscatter sensor (ABS). These instruments were deployed on stainless steel pipes that are 4.26 meters long. Each pipe was jetted into the sea floor to a depth of about 3 meters, leaving approximately 1.2 meters above the sediment interface. The instruments were mounted on a cantilever arm attached to the pipes approximately 40-60 cm above the bottom. The 3 offshore sites consisted of a trawl resistant bottom mount (TRBM) containing an Acoustic Doppler Current Profilers (ADCP) deployed in water depths of 8-10 meters. Sites were deployed and recovered on different days due to weather conditions. Additionally other data were collected from a dye study, a camera system located on the lighthouse, Wellen Radar (WERA) installed on the dunes, nearshore surveys and a benthic underwater generator.
After recovery of the instruments, proprietary software from each specific instrument manufacturer was used to download sensor measurements from each instrument and decode those measurements to instrument-specific data formats. The data were then converted from instrument-specific formats and calibrated. Units were modified to scientific EPIC-standard units (http://www.pmel.noaa.gov/epic/ ), and the data were stored in network common data format (NetCDF). EPIC is a set of standards that allow researchers from different organizations to share oceanographic data without having to translate "foreign" data types into the local vernacular. NetCDF is a very general, self-documenting, machine-transportable data format created and supported by the University Corporation for Atmospheric Research (UCAR) (http://www.unidata.ucar.edu/software/netcdf/ ). After the conversion, the data were carefully checked for inconsistencies due to instrument malfunctions and biological fouling and then edited to remove these spurious points. Also, the beginning and end of each data series were truncated to remove data collected out-of-water. The data were carefully checked at each stage of processing. After final editing, the data are considered to be the "best basic version" and include all variables recorded at the basic sampling interval. Best basic versions of most data files in NetCDF format are included in this report (see the Digital Data Files page).All data should be used and interpreted with care.