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CODAR Currents Newsletter Fall 2010
 
Special Energy Ocean Edition

Take a peek at various ways SeaSonde® data is being used to improve offshore energy operations in the oil sector as well as renewables.
SeaSonde currents nearest to the Deepwater Horizon leak site
Image shows SeaSonde currents (colored vectors) nearest to the Deepwater Horizon leak site superimposed on the National Oceanic Atmospheric Administration (NOAA) oil particle trajectory forecast (blue blotches). This data set (from 4 June 2010) and others collected throughout the disaster response period are posted online at the U.S. Integrated Ocean Observing System (U.S. IOOS) official leak response site.


O
ffshore oil and gas operators continue to thrive and play a vital role in global economies, while at same time making way for their newest neighbors in the water who attempt to harness significant power from the ocean area-- in the form of currents, winds and waves. This special edition newsletter focuses on ways in which SeaSonde data is being used by the broader offshore energy sector, to improve technology and operations and managing consequences. It is by no means comprehensive, so expect to see more articles on this topic in future newsletter editions!


INSIDE THIS ISSUE


Deepwater Horizon Oil Leak
SeaSonde data proves useful in response efforts to the disaster in the Gulf of Mexico.

Univ. of Alaska, Part 1
HF radar data benefitting Alaska oil industry and native communities.

Ocean Energy Testing &
Evaluation Range

SeaSondes in east Florida are part of Florida Atlantic University’s Center for Ocean Energy Technology to test and improve energy extraction devices.

Offshore Wind Farms
& the Role of SeaSonde Data

Rutgers University uses SeaSonde data in ways that offer money savings for utilities and New Jersey rate payers.

Portugal Starts Operational HF Radar
Observing Instituto Hidrografico deploys SeaSonde network in the Sines area.

A Sneak Peek at Nexgen Rapid Response Ocean Monitoring
CODAR and partners develop and demonstrate a self-contained rapid deployment SeaSonde along the rugged Norwegian coast.

Univ. of Alaska, Part 2
Sometimes the scientists at UAF have a very long commute! Also, take a look at the remote power solution these folks have developed specifically for SeaSonde equipment in Arctic environments.

TECH TIP
Can you really double your forward power with a simple pole?

2010 Riversonde® Grants Awarded
Meet the recipients of the 2010 RiverSonde equipment loan grants.

SeaSonde: Is it Cutting-Edge Technology, Fine Art...
or Both?

“Tecno@rt: Theinevitable meeting of art and technology in asustainable environment”

UPCOMING EVENTS


The BP Deepwater Horizon oil rig ablaze.
The BP Deepwater Horizon oil rig ablaze.
Image credit: U.S. Coast Guard.


SeaSonde antenna operating in Alabama.
SeaSonde antenna operating in Alabama.
SeaSondes Play Role in Gulf of Mexico Disaster Response


F
ive years after Hurricane Katrina’s wrath was felt by residents in the Gulf of Mexico, the area now faces another disaster. On 20 April 2010 the explosion on Deepwater Horizon oil rig set into motion the oil leak that flowed until 15 July and is now on record as the largest oil spill in U.S. history. Its impacts as well as required cleanup and remediation will continue for years.

Within days of the explosion, CODAR engineers worked alongside scientists at University of Southern Mississippi to complete installation of their 3 Long-Range SeaSonde radars and mobilize this network so that it would provide coverage of the surface currents from Mississippi as far east to Pensacola, Florida.

Data from this network, and another Long-Range SeaSonde network positioned along the west Florida shelf (owned and operated by University of South Florida), were loaded hourly into the US IOOS national HF radar network database and from there used by NOAA scientists alongside their models of circulation and oil transport in the Gulf.

A wider swath of scientists used this data and that from Rutgers University underwater glider fleet to compare with and to analyze the utility of the HyCOM and SABGOM models running in the Gulf.

While ocean circulation in the deep water areas of the Gulf can be resolved with confidence using satellite-derived data, the current circulation patterns on the shallower shelf areas are poorly observed by satellite as these areas are influenced less by geostrophic and tidal effects, but more by winds, bathymetry, and river discharge. These influences reduce the effectiveness of satellite-derived current information while emphasizing circulation nowcasts and forecasts that input data over the continental shelf. SeaSonde HF radar current patterns are the most obvious and critical nowcast observations that satisfy this need.



Please allow approx. 30 secs. for video to begin play


NEWS COVERAGE


Considerable press has been given to the use of SeaSondes in the Gulf of Mexico response. Of the writings, we especially like that article written by Paul Voosen which appeared in the New York Times online.
Click here for the full article



At left: San Francisco State University’s Jim Pettigrew explains to NBC Bay Area news reporter Vicky Nguyen the basics of how HF radar works, how it can help in the Gulf response effort, and also the incredible SeaSonde coverage along California’s coastline that represents the world’s most extensive HF radar network. The news video segment can be at the left
.


DeepWater Horizon Oil Spill
The website specially devoted to U.S. IOOS’ disaster response in the Gulf of Mexico (entry portal http:// rucool.marine.rutgers.edu/deepwater/ ) contains arguably the best collection of oceanographic information and analysis available for public viewing. We call special attention to the Deepwater Blog section (direct link is http://rucool.marine.rutgers.edu/deepwater/category/deepwater-blog/). Of the 127 postings made thus far, there are simply too many interesting entries involving SeaSonde data to list. So, instead we show below an excerpt from the blog dated 4 June 2010, (posted by Dr. Scott Glenn of Rutgers University) illustrating one specific example how SeaSonde data is being used.
The blog is posted online at http://rucool.marine.rutgers.edu/deepwater/category/deepwater-blog/page/8/


HF Radar tells the story for the Florida Coast.

DeepWater Horizon Oil Spill data set 1
Figure 1. This is the NOAA Oil Spill Forecast for June 3. The oil that is north of the Deepwater Horizon site was located directly south of the Mississippi/Alabama border, directly south of Mobile Bay. Very little is south of the Alabama/Florida border.

DeepWater Horizon Oil Spill data set 2
Figure 2. Here is the NOAA oil spill forecast forecast for June 4. There is a significant eastward shift in in the highest oil concentrations shown in the blue colors. The black line showing the outer boundary has shifted significantly to the north and east, making landfall in Alabama and Florida.

DeepWater Horizon Oil Spill data set 3
Figure 3. Now we overlay the surface current maps from the National HF Radar network. The shore-based radar systems are observing strong currents generally to the east. West of Mobile Bay, the strong currents are running to the southeast, moving the oil slick away from the Mississippi coast. East of Mobile Bay, the currents turn, heading northeast, toward the Florida coast, exactly how the oil is moving. The HF Radars are showing us where the oil is going and why. No wonder the U.S. Coast Guard uses HF Radar for Search And Rescue.

DeepWater Horizon Oil Spill data set 4
Figure 4. Now here is the HF Radar surface current map from the Florida shelf south of Tampa. The oil slick is just making it into the coverage area for these HF Radars. Currents here are alongshore generally to the north. The outer edge closest to the oil is heading northeast towards Tampa, but the currents closer in are running parallel to the coast.



University of Alaska at Fairbanks, Part 1:
HF Radar Data Benefitting Alaska Oil Industry & Native Communities
UAF field experts prepare to make antenna patten measurements from small skiff in the icy Chukchi sea. UAF field experts prepare to make antenna patten measurements from small skiff in the icy Chukchi sea. 
HF radar for ocean observing has a long history in Alaska starting back in 1976. At that time NOAA deployed CODAR units (predecessor to the SeaSonde®) as part of an environmental impact assessment in Lower Cook Inlet for benefit of the Bureau of Land Management (which at the time was responsible for managing offshore oil leasing on the outer continental shelf). Since then, Alaska maintains its status as one of the most challenging environments to deploy and operate HF radar, though the benefits of having its data for serving oil industry and others have always been great enough to justify the effort!

The HF radar team members at the University of Alaska, Fairbanks (UAF) School of Fisheries and Ocean Sciences have used their expertise to meet the challenges of radar deployments in the toughest of conditions. While deployments take them all around the state from the Gulf of Alaska in the South to the Beaufort Sea in the North, a present focus for 2010 is in Northwest Alaska’s Chukchi Sea.
SeaSonde antennas have been striped with bright reflective tape for alerting snow machine operators to their presence.
SeaSonde antennas have been striped with bright reflective tape for alerting snow machine operators to their presence.

With funding from the United States Dept. of the Interior, Bureau of Ocean Energy Management., Regulation & Enforcement Division, Conoco Phillips Alaska, Inc., and Shell Oil Company, UAF has set up Long-Range SeaSondes in Barrow, Wainwright, and <in process> Point Lay to provide data to the offshore energy industry. As a bonus, native Alaskan Communities may also use the outputs to predict how sea ice conditions may change during subsistence hunting activities.

The data collected in the Chukchi Sea will be used for oil spill risk analysis as well as Environmental Impact Statements. Shell Oil was scheduled to drill in the Chukchi Sea this summer, 2010, until the moratorium on drilling was handed down by the Obama Administration. In addition to SeaSondes, UAF is also deploying a six mooring array stretching out from the shoreline that will measure currents, waves, ice thickness, temperature, and salinity from August 2010 through August 2011. For the month of August 2010, two Webb Slocum gliders will undulate within the SeaSonde coverage.
Long-Range SeaSonde antennas operating in Chukchi Sea at Wainwright, Alaska.
UAF team members Hank Statscewich, Tom Weingartner & Rachel Potter
UAF team members Hank Statscewich, Tom Weingartner & Rachel Potter
SeaSonde-derived Chukchi Sea current map produced during 2009 deployment
SeaSonde-derived Chukchi Sea current map produced during 2009 deployment





      DANGER!!
  While most UAF field campaigns are carefully planned in advance, there are occasions when the radar team is called to action with only days or hours notice. Such was the case last year in Cook Inlet area, when Mt. Redoubt roared its ugly head. The volcanic eruption sent an avalanche of mud, known as a lahar, toward the oil storage tanks at the Drift River Oil Terminal (DROT) nearly causing an oil spill. The surprise lahar alerted people to the clear and present danger posed by Mt. Redoubt and possible devastation of local environment. As part of the emergency preparations UAF performed a rapid deployment of three SeaSondes in the area, including placement of a unit on Osprey Oil platform just west of the DROT.
Mt. Redoubt sending ash cloud into sky, 2009. Photo courtesy of James Isaak.  


 

SeaSonde’s Role in the Ocean Energy Testing & Evaluation Range at Florida Atlantic University’s Center for Ocean Energy Technology
Contributed by Shirley Ravenna, Florida Atlantic University
FAU Engineer Shirley Ravenna preparing ADCPs for deployment.   FAU Engineer Shirley Ravenna preparing ADCPs for deployment.  

A
s a necessary contribution to help advance ocean energy development, Florida Atlantic University’s (FAU) Center for Ocean Energy Technology (COET) is measuring, characterizing, and modeling ocean thermal and ocean kinetic resources available from the Gulf Stream Current in the Florida Straits. The measurement efforts initially involve stand-alone moored velocity and temperature measurements across the Straits in the Ft. Lauderdale area, surface-deployed water column profiling instruments, and shore-based ocean surface radar.

FAU’s COET is pursuing a phased approach to technology and infrastructure development. Ultimately, an offshore testing, measurement, and observation range is planned. This in situ laboratory will consist of not only ocean-current
energy-extraction device scaled system testing capabilities, but a comprehensive underwater and remote scientific observatory, including both resource and environmental measurement sensor and instrument suites. The phased approach is based upon a collective technology readiness level and regulatory development strategy. This first phase (underway) consists of shore-based coastal radar systems, offshore stand-alone moored current profiler instruments, and Conductivity Temperature Depth (CTD) profiling measurements.

The kinetic resource assessment consists of several ADCP deployed moorings which measure the velocity magnitude and direction of the water column at their locations and a SeaSonde® network measuring the complete current vector for the surface layer. The SeaSonde measurements overlay the information collected by the moored ADCP packages, and thus allow for inference of volumetric flow information. The thermal resource assessment consists of gathering vessel-deployed CTD cast profiles along several transects to quantify the thermal resource off the southeast coast of Florida. Initial resource assessments show that southeast Florida is an ideal geographic location for commercial ocean current and ocean thermal energy conversion (OTEC) device development. Continued measurements will help quantify and characterize a more detailed picture of the potentials for these marine renewable energies offshore of southeast Florida.
Surface current map from FAU SeaSonde network.

Surface current map from FAU SeaSonde network.





Ocean current energy extraction devices will likely be diverse in size, shape, and energy extraction methods. During the second phase of development, COET is preparing a simple scaled ocean current turbine, to generally address the spectrum of device-technology gap development. This turbine, in concert with the accompanying support infrastructure as a small-scale device test bed will be used as a research and development tool to advance the implementation of ocean-energy extraction devices. Leveraging test bed instrumented support infrastructure, device testing and demonstration, and correlated environmental and resource characterization data from a comprehensive ocean observatory, COET aims to provide ocean-energy device-testing methodologies and capability, a sufficient understanding and characterization of marine renewable energies in the Florida Straits, and an understanding of the potential ecological and environmental interactions of this developing ocean energy industry.


          FAU SeaSonde deployed at Haulover Beach Park in Florida





Offshore Wind Farms & the Role of SeaSonde Data –
Saving Money for Utilities and New Jersey Rate Payers






President Obama wants 20% of United States power coming from green energy by 2030. While this sounds like an aptly ambitious goal, it pales in comparison to that set by the state of New Jersey: source 30% of its electricity from green energy by 2020. Last summer the state celebrated its 4000th solar installation, proving it is rising to the challenge. But to fully achieve this lofty goal, New Jersey cannot rely on land-based equipment and must move to the water, capturing offshore wind power.
future location of NJ’s 350 MW offshore wind park, set for construction to start in 2012. Program led by NRG Bluewater Wind.
Image above shows the future location of NJ’s 350 MW offshore wind park, set for construction to start in 2012. Program led by NRG Bluewater Wind.
The New Jersey Board of Public Utilities (NJ BPU) is funding the Seal of the Great State of New  Jersey & New Jersey Board of Public Utilities (NJ BPU)development of offshore wind farms and along the way aims to save money for the utilities and NJ rate payers by optimal harnessing of such “green power”. Once installed, the daily operating cost of running a wind turbine is relatively uniform, regardless of actual power produced any given day. Utilities sell power by bidding certain quantities on spot energy market for prices that are set 24 hours in advance. If the utility can predict accurately how much wind energy they will create and have available the following day (to sell) then they can bid a larger quantity of power produced from the wind (that comes at no additional cost to the utility), and maximize their profit. New Jersey rate payers also benefit because a percentage of any such profits gets refunded to them. However, if the utility estimates poorly and oversells energy based on expected wind output then they need to derive that energy from another source (e.g. coal) -- as a result the utility can lose money and rate payers see no savings in their utility bills.
Rutgers University
NJ BPU has contracted scientists at Rutgers University to improve the atmospheric forecasts that utilities use in estimating potential green energy production. Rutgers’ very high resolution atmospheric forecast model, RU-WRF, is running with a 1 km resolution that is fine enough to resolve the physics of the critical sea breeze off the New Jersey coast. RU-WRF outputs information that NJ BPU can share with all utility companies. Rutgers is running an operational version used to provide information to weather service and also a research version they can use to experiment and tweak over time. The SeaSonde data outputs will be a critical tool used to validate the WRF model. Rutgers manages a SeaSonde network in the New York- New Jersey area providing 2-D current maps with both 1 km and 6 km resolution settings. Wind turbines will be positioned near center of 1 km grid coverage areas.

For the modeling and forecasting effort, the biggest variability near shore during peak power times is the diurnal sea breeze. The sea breeze is a wind field that moves across the coastal zone towards land, affected significantly by differences between the warm land surface temperature and the cool sea surface temperature. You can see its leading onshore edge using microwave radars, as this front side contains plenty of dust and particulate matter acting as an ideal scatter wall for the microwave signals. However, that’s all the microwave radar can see. The HF radar picks up from there by helping show the extent of the sea breeze and quantifying the spatial and temporal variability across the breeze field, that has until now been the critical missing information.

Maps showing diurnal variance ellipses (black crosses) and the major axis (color) of diurnal variability calculated from the HF radar system for (a) February–March 2005 and (b) April–May 2005.
“Maps showing diurnal variance ellipses (black crosses) and the major axis (color) of diurnal variability calculated from the HF radar system for (a) February–March 2005 and (b) April–May 2005.“

This figure and above description are published in Hunter, E., R. Chant, L. Bowers, S. Glenn, and J. Kohut (2007), Spatial and temporal variability of diurnal wind forcing in the coastal ocean, Geophys. Res. Lett., 34, L03607, doi:10.1029/2006GL028945.
How does the HF radar do this? Not giving away the recipe in this short article, in summary: Rutgers applies a series of post-processing techniques to the SeaSonde 2-D surface current maps that filter out specific influences on the surface currents, such as the tidal constituents, eventually isolating the wind-induced component of current at each 1 km grid point in the radar field. The intensity of the wind-induced surface current is very well correlated with what the winds above are doing spatially.

Additional Uses For RU-WRF Model & SeaSonde Outputs:

Wind Farm Design and Engineering Typically the technology engineers utilize what are called “Wind Resource Maps” (WRM) to design equipment, determine its ideal placement offshore and estimate energy production. The resource maps are rather crude, in the form of annual average maps. One task of the Rutgers team is using the model outputs and SeaSonde data in creating more sophisticated WRMs-- for each month, with data averaged for 3 hour segment across the day, to better match demand periods.

Verifying Performance
The WRF model and SeaSonde data can also be used to confirm that the wind turbines are working and delivering the power they’re supposed to over a range of various wind speeds and durations, and afterwards gauge the power harnessing effectiveness of that equipment.

Assisting Routine & Emergency
Ocean Operations

In addition to SeaSonde data being used to validate the model outputs, this same data can also be used to assist with field operations: during installation, routine O&M and any emergency responses that may be required. For these activities it’s good to know in realtime what the ocean current and wave conditions are for the area.
Example of annual Wind Resource Map for New Jersey area. Example of annual Wind Resource Map for New Jersey area.



Portugal Starts Operational HF Radar Observing
SeaSonde currents showed inside display screen of PORTUS BY QUALITASoceanographic information system.
SeaSonde currents showed inside display screen of PORTUS BY QUALITAS oceanographic information system.
T he deployment of two SeaSonde® HF Radars in the Sines area by the INSTITUTO HIDROGRÁFICO (IH) has been awarded to the engineering company QUALITAS. This system is part of the SIMOC project (www.hidrografico.pt/simoc.php), which has also the support of Sines Harbor Administration, and will monitor surface currents and waves in the southwest coast of Portugal.

The IH (Portuguese Hydrographic Office) is a state research laboratory, part of the Portuguese Navy, and is the main operational oceanographic institution in Portugal. Amongst its responsibilities is the establishment and maintenance of the national operational ocean observing network, which gives support to all Portuguese constituents along the its EEZ such as search and rescue activities, safe navigation and harbour operation.

The Sines area, positioned halfway between Lisbon and Algarve, was chosen as the first permanent HF Radar deployment area since it is one of the most sensible locations of the Portuguese coast, having a major petrochemical harbor, and directly to the south, a natural reserve (Natural Park of the Southwest of Alentejo). Environmental monitoring by means of HF radar is understood as a preventive action to improve safety along one of the heaviest ship traffic corridors in the world. The radar network will
complement the wave buoy deployed near the Sines Harbor (part of the national buoy network) as fixed monitoring systems, and allow a deeper knowledge of the circulation in this area.

Data retrieved by the system will be integrated into the PORTUS BY QUALITAS® oceanographic information system.

The radars will be operating from the Sines Harbor and Cape Sardão, these being the first two sites of the planned national network as foreseen in MONIZEE, the Portuguese Coast Monitoring Plan.

For more information regarding this project please contact:

Cte. Santos Fernandes of IH -
or
Pedro Agostinho of QUALITAS -

A Sneak Peak at the Next Generation of Rapid Response
Ocean Monitoring
CODARNOR AS, the Norwegian partner of CODAR Ocean Sensors, has been contracted to develop a self-contained rapid response SeaSonde® which can be deployed by helicopter or other means to remote and rugged locations along the Norwegian coast.

Initiated by the Norwegian Clean Seas Association for Operating Companies (NOFO) and cofinanced by Innovation Norway, the project is part of a development program aimed at improving oil spill response technology.

Representation of NOFO program rapid response SeaSonde
Representation of NOFO program rapid response SeaSonde
The current maps collected from these rapid-deployable systems will be delivered in real-time to improve oil spill response efforts by blending data with drift model currents for improved drift predictions and vessel management. Outfitting an HF radar system into a mobile unit for quick deployment is not a new idea. Groups at Texas A&M University and NOAA CO-OPS have integrated SeaSondes into vehicle-towed mobile trailers with off-the-shelf power and communications subsystems. Both groups have proven this type of integration and mobile setup successful and useful over multiple tests and deployments. Towed trailers, however, have inherent limitations such as accessible roads and travel times that are dictated by local conditions. Many coastal areas, especially in Norway, can be inaccessible by road and lack basic infrastructure, making a quick installation of an HF radar system difficult. By reducing the weight, integrating the antenna and power supply into the shelter and providing redundant communication options, it’s never been quicker to deploy an HF radar for emergency situations. Lighter and faster hardware is only part of the solution, though.

For more information or development updates on rapid response SeaSondes, please contact Laura Pederson
< > or
Dr. Anton Kjelaas
< >,
President, CODARNOR AS.
CODARNOR AS company president Dr. Anton Kjelass seen with helicopter deployable SeaSonde package
CODARNOR AS company president Dr. Anton Kjelass seen with helicopter deployable SeaSonde package

The end-users of surface current maps have to feel confident in the data delivered to them and be able to use it immediately. A dedicated web server running the PORTUS information system by Qualitas Instruments of Madrid (http://www.qualitasremos.com/) will serve as an interactive, user-friendly Google-based display of the data. PORTUS will provide real-time QA/QC and integrate standard products such as hourly surface current and error maps and perform Open Modal Analysis (OMA) on raw current data to fill out coverage in areas where only one site can measure or where shadowing may occur. One potential end-user of the data is also a development partner. The Norwegian Meteorological Institute (met.no) currently operates a 24-hour emergency oil spill service for Norwegian waters consisting of a suite of operational ocean models, wave forecast models and numerical weather prediction models. About 90 oil types that have been studied by SINTEF have been incorporated into their oil drift model. The information is available to the end user through a web service as well as on demand from the forecaster. Forecasters for met.no will use the OMA outputs of PORTUS to blend with model currents for improved spill response. The first rapid deployments of the prototype unit will take place late Summer in Finnmark, Norway.
Representation of NOFO program rapid response SeaSonde Representation of NOFO program rapid response SeaSonde
 





University of Alaska at Fairbanks, Part 2:
Just Another Day at The Office??
Read this and you’ll never complain aboutyour daily commute again!

U
AF being 300 miles away from the closest field sites, often with no traversable road between, routinely works small miracles in the transportation department. Gear is frequently subjected to at least 3 modes of transportation before reaching its destination. This can include auto trailer, boat, plane, seaplane, helicopter and oldfashioned hand carry across water and rocks.

Among the toughest challenges in Alaska is finding sites with a suitable powersupply and high-speed communications. When power and comms are not availablelocally, bringing these to the site increases the team’s “luggage” significantly.




Photo montage captures thisprocess of transport and setup inPrince William Sound.



Arctic Power Solution by UAF


Arctic Power Solution by UAFTo overcome the logistics nightmare of bringing in energy, UAF is developing a remote power system used specifically for SeaSonde equipment in Arctic environments. The remote power system has been designed such that no single piece weighs more than 55kg and is approximately no bigger than 1.2m x 2.4m. The device is equipped with four wind turbines, a solar array and a backup generator. The wind and solar power charge a large battery bank, which can provide five days of standard generation. If the batteries are drained and there’s no electricity from solar or wind, the module recharges using a biodiesel generator. With funding from the Department of Homeland Security (DHS), the 2,720kg remote power module will undergo a test deployment with a SeaSonde in Barrow, Alaska, running this summer through November.



Double Your Forward Power
with a Simple Pole?


What if someone told you that you could more than double your effective radiated power over the sea by simply sticking a post in the ground behind your combined transmit/receive SeaSonde antenna? No wires, cables, nothing! All with a special kind of “magic” post. Well, read on -- CODAR has done it!

The normal SeaSonde transmit antenna is a monopole or dipole, which has an omnidirectional pattern. That means power back over land, where you don’t need it. One way to focus power out over the sea is to use a second array element. We’ve done that before, and it works. But there’s the messy cables, and the complicated tuners and calibration.

The Yagi antenna is frequently used to focus power in a preferred direction. The old VHF TV antenna on your rooftop was a Yagi. That’s our basic concept.
• In a 2-element Yagi, the dipole you drive or feed has a passive reflector element close behind it, but not electrically connected -- a “parasite”.
• Its spacing and length determines how much power is focused forward. This is what we are doing here.

But do we have a special problem with the combined antenna?
• We want a focused directional pattern on transmit, but an omnidirectional pattern on receive -- how are both possible?
• In addition, we don’t want the closely spaced reflector to distort the patterns of the receive loops -- can this be done?

Here's how we solve the above problem.
• The passive reflector dipole behind the standard combined antenna needs to be tuned. So we put a tuning coil where the feed point would have been.
• We also insert a diode to break the circuit when the forward element is not transmitting. When cut in two like this, it can’t draw current and hence no longer interacts with the forward element during the receive cycle. This means it does not distort the loop or forward dipole patterns.
• Hence the two are directive on transmit, but the receive antenna patterns needed for bearing determination are intact because the rear element becomes invisible when the transmitter is off.

Examples of the transmit patterns are shown to the left. The green curve is the original omnidirectional pattern of a single dipole. The red and blue curves are the result of different length/spacing combinations with the rear element in place. We want to beam energy out to sea, which is to the right in the figure. However, in most cases we also want good shore-to-shore (North-South) coverage. The blue curve does that best. It increases the seaward field strength nearly 4 dB, for a predicted distance increase greater than 10 km at 13 MHz.

How Well Does It Work in Practice?
To answer that, we did tests over two months at BML. We alternated between rear reflector in place and operating for a few days, then removing it for a few days. We compared distance coverage by looking at the retrieved radial vector span alternating between the two states. A long period of time was desired, so we could average out short-term weather and current-related variations. The results are shown to the right.

In fact, the two-month comparison shows a nice 13 km coverage gain when the reflector post is in place, a bit more than predicted. This is a great alternative to have in your toolbox, for cases when you have the space available and want to push your coverage out further, without the hassle and expense of increasing your radiated power by 150%. We need to do more testing and burn-in on the diode switch that makes it electrically invisible on receive, and then it will become a standard product.
SeaSonde Remote Unit using Combined TX-RX Antenna with Passive Reflector behind it to boost forward power over the ocean.

SeaSonde Remote Unit using Combined TX-RX Antenna with Passive Reflector behind it to boost forward power over the ocean.





























2010 RiverSonde Equipment Grant Awards
Congratulations are in order for the two RiverSonde equipment grant recipients – David Honegger of Oregon State University (OSU) and Rutgers University pair Danielle Holden & Dakota Goldinger!
Rutgers University undergraduate students Danielle Holden and Dakota Goldinger are deploying the RiverSonde as part of the Department of Homeland Security (DHS) Summer Research Institute program. In June their team installed the RiverSonde unit atop Stevens Institute of Technology’s Center for Maritime Systems building at the edge of the Hudson River, directly across from Manhattan. Since the unit is high above land the range of the system is extending beyond the traditional 200-300m limit,



Background Image:
Students participating in the DHS Summer Research Institute Program install RiverSonde hardware atop building, with Hudson river and Manhattan skyline as backdrop.
reaching across the approx. 1150m wide channel. Data will be integrated into the New York Harbor Observing and Prediction System (NYHOPS) that models spatial and temporal variability of urban waters and microclimate. The team will both assimilate and compare the RiverSonde surface velocity measurements into the NYHOPS Hudson River Model with the goal of improving forecasts. Data from the RiverSonde are plotted in real-time and displayed on the Hudson River RiverSonde radial velocity vector map (green) with cross-channel velocity profile in magenta.
Hudson River RiverSonde radial velocity vector map (green) with cross-channel velocity profile in magenta.
Coastal Ocean Observation Laboratory website at http://www.rucool.org
     
Mr. Honegger is working towards a Ph.D in Civil Engineering with a disciplinary focus in Coastal and Ocean Engineering at Oregon State University. This Fall he will deploy the RiverSonde unit between the Newport, Oregon jetties that form a 300 meter wide channel. The data will be used to approximate the along-stream current magnitude and cross-stream current profile and determine the variability due to tides and precipitation events. The wave direction, wavelength and presence of breaking extracted from X-band marine radar images outside the jetties collected by Dr. Merrick Haller of OSU will be compared against the tidal current information gathered from the RiverSonde data to help characterize the importance of currents with respect to the wave breaking events. The RiverSonde data will also be compared against the modeled currents of a 3-D Yaquina Bay circulation model developed by Dr. James A. Lerczak (College of Oceanic & Atmospheric Sciences, OSU). The outcome of this circulation model validation will help Honegger introduce accurate tidal current time series into the Unstructured-grid Simulating Waves Nearshore (UnSWAN) spectral wave model and appropriately compare modeled wave-current interactions with those observed in the X-band marine radar images.
Grant recipients receive use of RiverSonde for 3 months, CODAR engineer assistance with installation, a training course offered at the recipient institution, and travel funds to present their findings at a scientific conference.
  These figures are excerpted from Honegger’s grant proposal. Figure 1: (a) Google Earth snapshot and estimated radar footprint near Newport, OR, (b) bathymetry near the antenna location, and (c) photograph of the existing marine radar station and planned RiverSonde installation location.



SeaSonde: Is it Cutting-Edge Technology, Fine Art...
or Both?


Whis magnificent church (below right), inspired by the basilica of Santa Sophia in Constantinople, was recent venue for special exhibition, “Tecno@rt: The inevitable meeting of art and technology in a sustainable environment”, in which, as event organizers say, “both disciplines explore their common fields and their progressive confluence”.

Featuring cutting edge ocean monitoring tools and concepts displayed in the fashion typical of a fine art show, SeaSonde antenna received special billing with front-and-center placement (image at right). This admittedly biased author thinks it stole the show! Tecno@rt was part of the 2010 European Maritime Day Stakeholder Conference that took place in Gijon, Spain 18-21 May.


SeaSonde Remote Unit using Combined TX-RX Antenna with Passive Reflector behind it to boost forward power over the ocean.
At right:
Sharing ocean observing ideas at the event are (from left to right) Dr. Scott Glenn of Rutgers University, Dr. Enrique Fanjul Alvarez of Puertos del Estado, Ms. Zdenka Willis of NOAA IOOS and Mr. Andres Alonso-Martirena Tornos of CODAR Europe.
 



UPCOMING EVENTS

CODAR WILL BE EXHIBITING AT THE FOLLOWING UPCOMING EVENTS:

2010 MEETING OF THE AMERICAS
8-13 August 2010 Foz do Iguacu, Brazil
We recommend participation in the OS02 session: Application of HF Radar Networks to Ocean Forecasts.

Oceans 2010
21-23 September 2010 Seattle, Washington Stop by and meet us at Exhibit Booth #219!

Mid-Atlantic Bight Physical Oceanography and Meteorology Meeting (MABPOM 2010)
26-27 October 2010 Hoboken, New Jersey


Links to these conference official web sites can be found in Upcoming Events Section of CODAR home page
www.codar.com

Crissy Field SeaSonde
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1914 Plymouth Street
Mountain View, CA 94043 USA
Phone: +1 (408) 773-8240
Fax: +1 (408) 773-0514
www.codar.com




  
 
 

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