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Codar Ocean Sensors, Ltd.
Mountain View, CA, United States
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Long R.M.,Codar Ocean Sensors, Ltd. | Barrick D.,Codar Ocean Sensors, Ltd. | Largier J.L.,University of California at Davis | Garfield N.,San Francisco State University
Journal of Sensors | Year: 2011

Wave data from five 12-13MHz SeaSondes radars along the central California coast were analyzed to evaluate the utility of operational wave parameters, including significant wave height, period, and direction. Data from four in situ wave buoys served to verify SeaSonde data and independently corroborate wave variability. Hourly averaged measurements spanned distance is 150km alongshore ×45km offshore. Individual SeaSondes showed statistically insignificant variation over 27km in range. Wave height inter-comparisons between regional buoys exhibit strong correlations, approximately 0.93, and RMS differences less than 50cm over the region. SeaSonde-derived wave data were compared to nearby buoys over timescales from 15 to 26 months, and revealed wave height correlations R = 0.85 0.91 and mean RMS difference of 53cm. Results showed that height RMS differences are a percentage of significant wave height, rather than being constant independent of sea state. Period and directions compared favorably among radars, buoys, and the CDIP model. Results presented here suggest that SeaSondes are a reliable source of wave information. Supported by buoy data, they also reveal minimal spatial variation in significant wave height, period, and direction in coastal waters from ∼45km × ∼150km in this region of the central California coast. Small differences are explained by sheltering from coastal promontories, and cutoff boundaries in the case of the radars. Copyright © 2011 Regan M. Long et al.

Roarty H.J.,Rutgers University | Smith M.,Rutgers University | Glenn S.M.,Rutgers University | Barrick D.E.,Codar Ocean Sensors, Ltd.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The marine transportation system (MTS) is a vital component of the United States Economy. Waterborne cargo accounts for more than $742 billion of the nation's economy and creates employment for 13 million citizens. A disruption in this system would have far reaching consequences to the security of the country. The US National High Frequency radar network, which comprises 130 radar stations around the country, became operational in May 2009. It provides hourly measurements of surface currents to the US Coast Guard for search and rescue (SAR). This system has the capability of being a dual use system providing information for environmental monitoring as well as vessel position information for maritime security. Real time vessel detection has been implemented at two of the radar stations outside New York Harbor. Several experiments were conducted to see the amount vessel traffic that the radar could capture. The radars were able to detect a majority of the vessels that are reporting via the Automatic Identification System (AIS) as well as 30 percent of mid to large size vessels that are not reporting via AIS. The radars were able to detect vessels out to 60 km from the coast. The addition of a vessel detection capability to the National HF radar network will provide valuable information to maritime security sector. This dual use capability will fill a gap in the current surveillance of US coastal waters. It will also provide longer-range situational awareness necessary to detect and track smaller size vessels in the large vessel clutter. © 2013 SPIE.

Barrick D.,Codar Ocean Sensors, Ltd. | Lipa B.,Codar Ocean Sensors, Ltd.
2015 IEEE/OES 11th Current, Waves and Turbulence Measurement, CWTM 2015 | Year: 2015

Two recent sets of HF radar observations in the Atlantic by SeaSondes have observed unexpected periodic modulations of significant wave height at the M2 tidal and inertial frequencies. These are examined and related to the underlying, strong currents. They are interpreted in terms of kinematic advection influences that change the first-order wave characteristics due to frequency dispersion. © 2015 IEEE.

Whelan C.,Codar Ocean Sensors, Ltd. | Hubbard M.,Codar Ocean Sensors, Ltd.
OCEANS 2015 - MTS/IEEE Washington | Year: 2015

Multi-static surface current vector data was processed for two different HF Radar networks, one measuring currents off the East Coast of the U.S. and the other measuring currents in the Malta Channel. Some effects of adding multi-static data are shown, including decreases in 2-D total vector uncertainties, increase in percent coverage within the network grid and increases in HF radar coverage area. © 2015 MTS.

Kjelaas A.G.,CODARNOR AS | Whelan C.,Codar Ocean Sensors, Ltd.
Sea Technology | Year: 2011

CODARNOR AS has partnered with CODAR Ocean Sensors, QUALITAS Remos (Madrid, Spain) and the Norwegian Meteorological Institute, to develop a rapid-response SeaSonde for the rugged and remote Norwegian coastline in response to the Oil Spill Response 2010 launched by the Norwegian Clean Seas Association for Operating Companies and the Norwegian Coastal Administration. The objectives involves the development of a mobile SeaSonde high-frequency radar unit that can be rapidly deployed to the coast of Norway to aid in effective and efficient oil spill response. The project aimed to accomplish this through developing a data service that provides high-quality SeaSonde-derived 2D current fields to the Norwegian Meteorological Institute in near real time. High-frequency radar currents from the nine-day experiment in September 2010, during which both radars operated, were blended with ocean model current fields to produce a continuous gridded data set.

Barrick D.,Codar Ocean Sensors, Ltd. | Fernandez V.,Qualitas Remos | Ferrer M.I.,Qualitas Remos | Whelan C.,Codar Ocean Sensors, Ltd. | And 2 more authors.
Ocean Dynamics | Year: 2012

In order to address the need for surface trajectory forecasts following deployment of coastal HF radar systems during emergency-response situations (e.g., search and rescue, oil spill), a short-term predictive system (STPS) based on only a few hours data background is presented. First, open-modal analysis (OMA) coefficients are fitted to 1-D surface currents from all available radar stations at each time interval. OMA has the effect of applying a spatial low-pass filter to the data, fills gaps, and can extend coverage to areas where radial vectors are available from a single radar only. Then, a set of temporal modes is fitted to the time series of OMA coefficients, typically over a short 12-h trailing period. These modes include tidal and inertial harmonics, as well as constant and linear trends. This temporal model is the STPS basis for producing up to a 12-h current vector forecast from which a trajectory forecast can be derived. We show results of this method applied to data gathered during the September 2010 rapid-response demonstration in northern Norway. Forecasted coefficients, currents, and trajectories are compared with the same measured quantities, and statistics of skill are assessed employing 16 24-h data sets. Forecasted and measured kinetic variances of the OMA coefficients typically agreed to within 10-15%. In one case where errors were larger, strong wind changes are suspected and examined as the cause. Sudden wind variability is not included properly within the STPS attack we presently employ and will be a subject for future improvement. © 2011 Springer Science+Business Media, LLC.

Codar Ocean Sensors, Ltd. | Date: 2011-08-31

An antenna configuration is described for high frequency (HF) or very high frequency (VHF) radars contained in a single vertical post. The radar may include a vertical dipole or monopole transmitting antenna collocated with a three-element receive antenna. The three antennas including two crossed loops and a vertical element are used in a direction-finding (DF) mode. Isolation between the three antennas produces high quality patterns useful for determining target bearings in DF mode. The single vertical post is sufficiently rigid mechanically that it may be installed along a coast without guy wires.

Agency: Department of Commerce | Branch: National Oceanic and Atmospheric Administration | Program: SBIR | Phase: Phase II | Award Amount: 399.88K | Year: 2011

Over 300 HF RADARs worldwide are producing ocean surface data that is used in oil spill response, search & rescue, vessel traffic management, and research. In the U.S. there are 100+ systems supplying real-time data to the Coast Guard, NOAA IOOS, OR&R and other operational groups. To provide the highest quality data to stakeholders, systems should be calibrated by measuring the receive antenna pattern. For the typical HF radar, this measurement is currently made with a portable transponder on a boat 1-2 km away. This method, while robust, is costly and limited by sea conditions. We demonstrated in Phase I that by associating AIS vessel identifications, which provide ship positions, with vessel radar echoes in HF radar data it is possible to reproduce the antenna pattern. The objective of Phase II research is to implement the method operationally. The prototype will consist of software to acquire AIS ship data and combine it with HF radar cross-spectra to produce antenna pattern measurements and their statistics. To accomplish this objective we will answer the remaining research questions from Phase I, expand the method to other operational HF radar bands (5, 25 and 42 MHz), and develop quantitative data quality metrics.

Agency: Department of Commerce | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 94.98K | Year: 2010

Of more than 100 HF Radars operating within the Integrated Ocean Observing System (IOOS), more than half run either without recommended receive antenna pattern calibrations or with out-of-date calibrations, despite potential compromises to data quality. Cost is the primary inhibitor of frequent calibration, which generally requires a technician to drive a small vessel with mounted transponder in arcs around the antenna. Large vessels now broadcast their positions and speed approximately every 10 seconds using the Automatic Identification System (AIS). Echo from these vessels also appear as signals in real-time HF Doppler spectra. We propose using AIS ship position and speed, along with corresponding HF Doppler ship echo, to determine receive antenna patterns in near real time. The methods proposed here will result I a software product which would both reduce the cost of calibration of IOOS HF radars and significantly improve IOOS surface current data quality.

Codar Ocean Sensors, Ltd. | Date: 2014-03-14

A multi-static radar system for monitoring water surface targets is provided. The multi-static radar system may include a first and second radar, a state machine, and a signal processor. The radars may be located in separate locations and synchronized using timing signals. The state machine may be configured to determine, using the timing signals, start times and end times of radio frequency signal modulations for each radar. A concept of negative pseudo-range is provided, whereby the modulation start times are configured to allow pseudo-negative time delays at as many as half of the radar receivers, thereby doubling the multi-static echo detections. The signal processor may be configured to simultaneously receive and process the echoes of the radar signals received at the radars to determine position and velocity vectors for the monitored water surface targets.

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