Data from Three Recent Studies Released in the USGS Oceanographic Time-Series Data Collection
Three new oceanographic time-series datasets were recently released in the USGS Oceanographic Time-Series Data Collection. Two are from experiments conducted near the Martha’s Vineyard Coastal Observatory south of Martha’s Vineyard, Massachusetts, and the third was collected at Town Neck Beach in Sandwich, Massachusetts. A map showing the study sites is shown, below.
Oceanographic and water-quality measurements collected south of Martha’s Vineyard, Massachusetts, 2014–2015
The first of two experiments near the Martha’s Vineyard Coastal Observatory was conducted as part of the “Bottom Stress and the Generation of Vertical Vorticity over the Inner Shelf” (National Science Foundation [NSF] STRESS project) supported by the National Science Foundation and the USGS Coastal and Marine Geology Program. This study was a collaborative effort with co-principal investigators John Trowbridge and Malcolm Scully, both of the Woods Hole Oceanographic Institution, and Chris Sherwood of the USGS Woods Hole Coastal and Marine Science Center. Observations were collected from two kinds of platforms at seven sites near the Martha’s Vineyard Coastal Observatory.
Four-legged platforms (quadpods) were deployed at two sites twice: first between July 1 to August 8, 2014; September 9 to September 23, 2014; and November 11, 2014 to January 14, 2015. Two deployments were necessary to sample a range of conditions, given the limited endurance of battery power and data storage. The initial plan called for back-to-back deployments with a short interval in between to offload data and replace batteries, but foul weather and ship unavailability prevented this outcome. One quadpod was deployed at a shallow site (nominal 15 meters, 49 feet) and one at a deep site (nominal 20 meters, 65 feet). The quadpods supported multiple instruments that provided measurements of waves, current profiles, bottom stress, bottom topography, temperature, salinity, and turbidity.
Newly developed low-profile platforms for obtaining bottom stress measurements, called NIMBBLEs (New Instrument for Making Benthic Boundary Layer Evaluations), were deployed at five other sites. Two NIMBBLEs were deployed at different depths and on different types of seafloor in three successive deployments: July 1 to August 8; September 9 to September 23; and November 11 to January 14, 2015. The NIMBBLEs measured current profiles with upward-looking acoustic-Doppler velocimeters, bottom stress with a pair of acoustic-Doppler velocimeters, and temperature with a high-resolution temperature logger.
Data from this experiment may be accessed at:
Oceanographic and water-quality measurements collected south of Martha’s Vineyard, Massachusetts, November–December, 2015
A follow-on to the NSF STRESS experiment was conducted between November and December 2015 as part of the Coastal Model Applications and Field Measurements Project. The objective of this experiment was to compare estimates of bottom shear stress made from a quadpod with those from a nearby NIMBBLE at adjacent sites near Martha’s Vineyard Coastal Observatory. The two platforms were equipped with instruments like those deployed in the NSF STRESS experiment. The goal was to assess the influence of platform characteristics (quadpod versus low-profile platforms) on estimates of bottom stress. Although this dataset was collected primarily to evaluate methods for measuring bottom shear stress, it also provides useful information on waves, currents, and sediment transport.
Data from this experiment may be accessed at:
Oceanographic, atmospheric, and water-quality measurements at Town Neck Beach, Sandwich, Massachusetts, 2016
Town Neck Beach in Sandwich has experienced chronic erosion and is the site of ongoing mapping and measurement efforts conducted as part of the Barrier Island Evolution Research and Remote Sensing Coastal Change projects. Five pressure sensors were deployed on January 22, 2016, in advance of a Nor’easter that hit the site, causing dune retreat and overwash. The instruments were recovered the day after the storm (January 25). One sensor was mounted on a lead disk and placed near the end of a groin extending from the beach, just below the low-tide mark. This sensor recorded at 4 hertz (Hz) and measured waves and tides. Another was placed on a piling in a tidal creek behind the barrier beach; this measured every 6 minutes and recorded tides. Two pressure sensors were deployed on the beach in an overwash channel. These were submerged only when large waves occurred at high tide, and recorded waves and water levels at 2 Hz. An atmospheric pressure sensor was deployed about 2 meters (6 feet) above sea level to provide corrections for the other pressure sensors.
Following the storm, a small platform dubbed the nanopod was deployed offshore from February 10 to May 20, 2016. Instruments on this platform measured currents, waves, water temperature, salinity, and turbidity.
Offshore mapping activities were conducted in the spring of 2016. Two pressure sensors were deployed from May 10 to June 16, 2016, to provide tidal corrections. One was located at the end of the groin to provide measurements of waves and tides, and the second was deployed about 2 meters (6 feet) above sea level to record atmospheric pressure.Data from these instruments may be accessed at:
in this issue:
New Studies Included in Oceanographic Time-Series Data Collection