Mike Muglia

Operation and application of a regional high-frequency radar network in the Mid-Atlantic Bight

The Mid-Atlantic Regional Coastal Ocean Observing System (MARCOOS) High-Frequency Radar Network, which comprises 13 long-range sites, 2 medium-range sites, and 12 standard-range sites, is operated as part of the Integrated Ocean Observing System. This regional implementation of the network has been operational for 2 years and has matured to the point where the radars provide consistent coverage from Cape Cod to Cape Hatteras. A concerted effort was made in the MARCOOS project to increase the resiliency of the radar stations from the elements, power issues, and other issues that can disable the hardware of the system. The quality control and assurance activities in the Mid-Atlantic Bight have been guided by the needs of the Coast Guard Search and Rescue Office. As of May 2009, these quality-controlled MARCOOS High-Frequency Radar totals are being served through the Coast Guards Environmental Data Server to the Coast Guard Search and Rescue Optimal Planning System. In addition to the service to U.S. Coast Guard Search and Rescue Operations, this data supports water quality, physical oceanographic, and fisheries research throughout the Mid-Atlantic Bight.

Implementing Quality Control of High-Frequency Radar Estimates and Application to Gulf Stream Surface Currents

AbstractQuality control procedures based on nonvelocity parameters for use with a short-range radar system are applied with slight modification to long-range radar data collected offshore of North Carolina. The radar footprint covers shelf and slope environments and includes a segment of the Gulf Stream (GS). Standard processed and quality controlled (QCD) radar data are compared with 4 months of acoustic Doppler current profiler (ADCP) time series collected at three different sites within the radar footprint. Two of the ADCP records are from the shelf and the third is on the upper slope and is frequently within the GS. Linear regression and Bland–Altman diagrams are used to quantify the comparison. QCD data at all sites have reduced scatter and improved correlation with ADCP observations relative to standard processed data. Uncertainty is reduced by approximately 20%, and linear regression slopes and correlation coefficients increase by about 0.1. At the upper slope site, the QCD data also produced a sig...

Gulf stream marine hydrokinetic energy resource characterization off Cape Hatteras, North Carolina USA

The Gulf Stream off North Carolina (NC), USA has current velocities that approach 2 ms-1 and average volume transports of 90 Sv (1 Sv= 106 m3s-1) off of Cape Hatteras, making it the most abundant MHK (Marine Hydrokinetic Energy) resource for the state. Resource availability at a specified location depends primarily on the variability in Gulf Stream position, which is least offshore of Cape Hatteras after the stream exits the Florida Straits. Proximity to land and high current velocities in relatively shallow waters on the shelf slope make this an optimal location to quantify the MHK energy resource for NC. Multi-years of consistent current measurements beginning in August of 2013 from a moored 150 kHz ADCP at an optimal location for energy extraction quantify the available energy resource and its variability, and establish the skill of a regional ocean circulation model in predicting the MHK energy resource. The model agrees well with long term observed current averages and weekly to monthly fluctuations in the currents. Comparisons between the model and ADCP observed currents, and power density demonstrate the significant inter-annual variability in the Gulf Stream power density.

Continuous Flow of Upper Labrador Sea Water around Cape Hatteras

Six velocity sections straddling Cape Hatteras show a deep counterflow rounding the Cape wedged beneath the poleward flowing Gulf Stream and the continental slope. This counterflow is likely the upper part of the equatorward-flowing Deep Western Boundary Current (DWBC). Hydrographic data suggest that the equatorward flow sampled by the shipboard 38 kHz ADCP comprises the Upper Labrador Sea Water (ULSW) layer and top of the Classical Labrador Sea Water (CLSW) layer. Continuous DWBC flow around the Cape implied by the closely-spaced velocity sections here is also corroborated by the trajectory of an Argo float. These findings contrast with previous studies based on floats and tracers in which the lightest DWBC constituents did not follow the boundary to cross under the Gulf Stream at Cape Hatteras but were diverted into the interior as the DWBC encountered the Gulf Stream in the crossover region. Additionally, our six quasi-synoptic velocity sections confirm that the Gulf Stream intensified markedly at that time as it approached the separation point and flowed into deeper waters. Downstream increases were observed not only in the poleward transport across the sections but also in the current’s maximum speed.

Measuring the landward gulf stream front variability off Cape Hatteras with HF radar

A decade of coastal ocean radar surface current observations of the Gulf Stream off Cape Hatteras, NC have been collected that offer to provide key new insights into the temporal and spatial variability of the Gulf Stream in this region. The Gulf Stream is believed to have a profound influence on the complex current dynamics off of Cape Hatteras, NC that result from the convergence of many different water masses in the region. Although essential to understanding oceanography off the NC coast, and to linkages beyond the region, Gulf Stream variability in this area has been difficult to quantify because of the challenge involved in obtaining observations of consistent spatial and temporal resolution over long time periods. Analysis of Long Range Seasonde Coastal Ocean Radar (Codar) ocean surface current measurements from two sites in NC may provide estimates of the landward Gulf Stream edge over a nearly continuous ten-year period. Radar surface current measurements are made hourly, more frequently than satellite measurements, and provide more consistent coverage of the Gulf Stream than many historical measurement techniques. The 5MHz radars typically make surface current measurements across the entire cyclonic shear zone on the landward side of the Gulf Stream. These measurements may provide methods to define Gulf Stream location, width, transport and variability of these properties over time and alongshore, providing insights into the current dynamics off Cape Hatteras, NC. We here present a method to identify the landward Gulf Stream position and width of the cyclonic shear zone from radar surface currents. The method of front detection developed associates the landward Gulf Stream front with maxima in the radial current shears. Maxima are chosen within regions of consistent coverage over the time period sampled. The locations where the Gulf Stream first enters and exits the radar coverage area are apparent as large radial speeds measured by the radar, and one bearing is chosen from each region for analysis. However in a region between these two zones the Gulf Stream is perpendicular to the radials and the method can not be used. This method can be applied to each of three radars located in the vicinity of Cape Hatteras.

Identifying the shoreward Gulf Stream front at Cape Hatteras with Coastal Ocean Radar surface currents

Surface currents off of Cape Hatteras North Carolina observed with a 5 MHz coastal ocean radar were analyzed to determine the location and variability of the shoreward edge of the Gulf Stream based on the region of maximum horizontal shear. The method for identifying the front is described in detail. A Coastal Ocean Radar (Codar) from Codar Ocean Sensors installed on the beach in Buxton, North Carolina has been operating from the fall of 2003 until the present. The Codar measures the radial component of the surface current and has a range from 100 to 200 km with spatial resolution decreasing as a function of range in 5.85 km range cell increments. Each radial vector produced is an average in an annulus bounded by a 5.85 km range difference and a five-degree bearing difference. The most probable location for the shoreward location of the Gulf Stream front is identified by the maximum horizontal shear in the radial velocities. Frontal locations are estimated by the maximum derivative of the radial speed with respect to bearing at a given range, and by the maximum derivative with respect to range at a given bearing. A third order piecewise spline curve was then fit to the combined set of gradient components. The locations where the Gulf Stream first enters and exits the radar coverage area are apparent in the large radial speeds measured by the radar, however in a region between these two zones the Gulf Stream is perpendicular to the radar, and the radar can not provide a good approximation for stream location based on this method.