USGS OFR 2011-1156: Carolinas Coastal Change Processes Project Data Report for Observations near Diamond Shoals, NC from January-April 2009, Methods

Click on figures for larger images.

Figure 1. Figure 1 caption. Location map for Cape Hatteras, North Carolina. Markers are placed to identify locations of moorings.

Figure 2. The Flobee tripod located at the north site. Photograph by Sandra Baldwin.

Figure 3. The North site minipod post recovery. Photograph by Sandra Baldwin.

Figure 4. The North surface buoy. Photograph by Sandra Baldwin.

Figure 5. The Flobee tripod deployed at the South site. Photograph by Sandra Baldwin.

Figure 6.The North and South surface buoys. Photograph by Sandra Baldwin.

Figure 7.The micropod tripod deployed off the tip of Cape Hatteras. Photograph by Sandra Baldwin.

Figure 8.U.S. Geological Survey employees deploying the grab sampler. Photograph by Sandra Baldwin.

The field program consisted of deploying equipment at three sites: North, South, and Tip (fig. 1). The North site consisted of a large "Flobee" tripod to measure bottom boundary layer (BBL) properties, a small minipod for mean-flow measurements, and a surface mooring. The South sites consisted of a Flobee BBL tripod and a surface mooring. The Tip site only had a micropod for mean-flow measurements. All instrumentation was deployed on January 12, 2009. Tripods at each site were recovered on different days as a result of weather conditions during the recovery. Details, including deployment locations, equipment mounted on the tripods at each site, and sensor elevations for each site, are provided below. Additional description of the deployment is provided in Martini and others (2009).

North Site

North Flobee
The North Flobee was located at 35.17863° N, 75.42292° W and was deployed on the seafloor at a water depth of 14.7 meters. Instruments mounted on this tripod consisted of an Acoustic Doppler Current Profiler (ADCP), Acoustic Doppler Velocimeters (ADVs), Optical Backscatter Sensors (OBSs), an Acoustic Backscatter Sensor System (ABSS), a Pulse-Coherent Acoustic Doppler Profiler (PCADP), Sontek hydra systems, Seatech transmissometers, Paroscientific (Paros) Pressure Sensors, a Sea-Bird SEACAT, and a Sea-Bird MicroCAT (fig. 2). During the deployment the tripod tipped over near mid April. This created substantial tilt of the sensor measurements on the tripod. Velocity and other data that were jeopardized have been removed from the dataset. Data from some instruments, such as pressure and temperature, were retained but may show an offset at that event. This tripod was recovered on May 10, 2009.

North Minipod
The North Minipod was deployed at 35.1783° N, 75.423355° W, at a water depth of 14.8 meters. Instrumentation consisted of an ADCP, a time-series visual image camera with a flash, a pencil beam and rotating sonar imaging system, a Sea-Bird SEACAT, a Seatech transmissometer, a laser in situ scattering and transmissometer instrument (LISST), and an Aquadopp Acoustic Profiler (fig. 3). This tripod was recovered on May 10, 2009.

North Surface Mooring
The North surface mooring was deployed at 35.177867° N, 75.422617° W, at the water surface. Instrumentation consisted of ARGOS (Seimac CML) and Iridium (Xeos melo) satellite beacons on the buoys to track position, a Sea-Bird SEACAT, a Sea-Bird MicroCAT, and a pressure and temperature sensor (PT) (fig. 4). This mooring was recovered on May 1, 2009.

South Sites

South Flobee
The South Flobee was deployed at 35.12958° N, 75.49204° W, at a water depth of 14.0 meters. Instrumentation mounted on the tripod consisted of an ADCP, ADVs, OBSs, an ABS system, a PCADP, Sontek hydra systems, Seatech transmissometers, Paros pressure sensors, a Sea-Bird SEACAT, and a Sea-Bird MicroCAT (fig. 5). This tripod was recovered on May 10, 2009.

South Surface Mooring
The South surface mooring was deployed at 35.12895° N, 75.49187° W, at the water surface. Instrumentation consisted of ARGOS (Seimac CML) and Iridium (Xeos melo) satellite beacons on the buoys to track position, a Sea-Bird SEACAT, and a PT (fig. 6). This tripod was recovered on May 1, 2009.

Tip Site

Tip Micropod
The micropod was deployed at 35.098985° N, 75.376055° W, at a water depth of 23.7 meters. Instruments mounted on this tripod consisted of an upward-looking ADCP, a Sea-Bird SEACAT, and a Seatech transmissometer (fig. 7). A change in the deployment depth at the Tip Micropod site resulted in data that did not reach the surface. This tripod was recovered on May 1, 2009.

Sediment Study

Surficial grab samples of sediment were obtained at the deployment locations to determine characteristics of the seabed. The samples were analyzed by the USGS Sediment Lab in Woods Hole for grain-size distribution, information that is critical to understanding the formation of the shoal and the regional sediment dynamics (fig. 8).

Field Program