Update on the Mid Atlantic Bight Ocean Surface Currents Network

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CODAR High Frequency Radar (HF-RADAR) systems are distributed along the U.S. coast throughout the Mid-Atlantic Bight. These systems acquire data on ocean surface currents from within a mile of the shore to more than 100 miles offshore. Data from these systems is used regularly by researchers, the U.S. Coast Guard, and Department of Homeland Security.

We are now displaying an up to date coverage metric on the daily, weekly and yearly coverage of the network.  The link to these performance metrics can be found here http://marine.rutgers.edu/~codaradm/images/stats/. An example of the metric from September 1, 2011 to December 16, 2011 is given in Figure 1. The metric shows that we are nearly at our goal of 80% spatial coverage 80% of the time.

We continue to upgrade equipment as funding allows (e.g. new single transmit/receive antenna at Montauk Point, NY).  We reestablished the 5 MHz system Wildwood that was down for approximately 1 year due to the closure of the US Coast Guard LORAN Support Unit in Wildwood.  The site was relocated just south on the Coast Guard Training Center in Cape May, NJ.  We also added two 13 MHz systems in Brant Beach and Brigantine NJ that will support the Rutgers project of mapping the spatial resource of wind energy of the coast of New Jersey.

Ocean Power Technologies, a small and medium enterprise based in Pennington, NJ used the surface currents from the long range system to evaluate the performance of their littoral PowerBuoy during its deployment from August to October 2011.


Figure 1Figure 1: Temporal and spatial coverage of the long range HF radar network in the Mid Atlantic Regional Association Coastal Ocean Observing System.

When a system is installed a checklist is followed to ensure that the system is installed correctly. That checklist is found here: http://sentinel.marine.rutgers.edu/sites/macoora/files/downloads/data/SOP_MARCOOS_Long_Range_Radar.pdf
All the sites in the network are standardized based on the operating frequency of the radar. This standardization table is found in Table 1. Once the system is installed it is remotely inspected once a week by the operators checking 10 components of the radar data stream to ensure the data is of the highest quality.

Table 1: Critical parameters in the radial processing stream

Parameter 5 MHz 13 MHz 25 MHz
Sweep Rate (Hz) 1 2 2
Velocity Resolution (cm/s) 3 4.5 2
CSS Averaging Period (min) 60 15 15
CSS Output Period(min) 30 10 10
Radial Coverage (min) 180 75 75
Radial Output Period (min) 60 60 30

On the Quality Assurance and Quality Control effort, we have focused on the sensitivities of the optimal interpolation (OI) radial combining method. We have software that calculates a random flight of the virtual drifters using the surface currents from the High Frequency radar. We have experimented with the parameters that are input into the OI algorithm. An example from one of the runs is shown in Figure 2. For these simulations we released 1000 virtual particles and calculated the centroid of the drifters at each time step (green line). The termini of the virtual drifters are shown as the blue dots and the 95th percentile area of the drifters is shown as the gray shaded boxes. Our initial findings indicate that the OI method places the virtual track 30% closer to the actual drifter after 24 hours compared with the unweighted least squares drifters.

Figure 2Figure 2: Comparison between SLDMB 43484 (red) and virtual CODAR drifter (green) for a 96 hour trajectory using the optimal interpolation combining method with Sx 10 km and Sy 25 km.

 

BRMRCombined transmit receive antenna at Brigantine SeaSonde site

 

 

BRNTCombined transmit receive antenna at Strathmere SeaSonde site

 

 

RATHCombined transmit receive antenna at Brant Beach SeaSonde site

 

 

WoodPhoto of the 13 MHz site in North Wildwood. The antenna is shown on the right with the electronics enclosure on the left. The CODAR van provides a good scale