September 2012
Status of U.S. HF Radar National Network (HFRNet)
Contributed by L. Hazard, M. Otero, T. Cook, T. de Paolo, & E. Terri!, Scripps Institution of Oceanography |
The success and continued expansion of a high frequency (HF)
radar national network for the distribution of coastal surface
currents has become possible through the dedication and
partnerships of multiple institutions, federal and non-federal
agencies, local and state governments, and private companies. The
U.S. Integrated Ocean Observing System (U.S. IOOS®) is dedicated
to maintaining the U.S. network and beginning to reach out to
global partners as these data are used in universal applications for
the health and safety of human and marine populations. |
 HF Radar site growth in U.S. from 2003 - present.
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The Coastal Observing Research and Development Center
(CORDC) at Scripps Institution of Oceanography (SIO) leads the
development and administration of the HF Radar National
Network (HFRNet) for distribution of HF radar derived surface
currents. The HF-Radar Network started as a prototype with a
single portal and node and 4 sites in December 2003 and has since
grown to an operational status with over 4 million radial files
produced by 133 sites from 29 participating institutions as of
September 2012 as shown in adjacent figure. Central repository
nodes have been deployed at the National Data Buoy Center
(NDBC), on the west coast at Scripps Institution of Oceanography (SIO), and east coast at Rutgers University, to demonstrate an
end to end distributed data. Site aggregators are currently deployed at eleven partnering institutions including Oregon State
University; San Francisco State University; Monterey Bay Aquarium Research Institute; California Polytechnic State University;
University of California, Santa Barbara; University of Southern California; Scripps Institution of Oceanography; University of
Maine; Rutgers University; University of Southern Mississippi; and University of Miami. The U.S. IOOS program has supported
the standards-based ingest and delivery of HF radar data. Standardized data formats and access methods enable surface-current
data to be ingested by national tactical decision aids, such as those used by the U.S. Coast Guard for search-and-rescue, and
NOAA for oil spill tracking and abatement. Coastal applications utilizing HF radar derived surface currents transcend all coasts.
The first Group on Earth Observation (GEO) Global High Frequency Radar meeting was held in London, England in March,
2012. A pilot project to extend the distributed data management system to global partners will begin next year initially with the
Republic of Korea. U.S. and Korean partners will collaborate in all aspects of HF radar operations including system deployment,
maintenance, data distribution, and products.
HFRNet Data Integration into Search and Rescue Optimal Planning (SAROPS)
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Graphical representation of data path from site to SAROPS tool. |
Full HFRNet integration into the U.S. Coast Guard Search and Rescue Optimal Planning System (SAROPS) has occurred in a
phased approach in partnership with the United States Coast Guard (USCG), CORDC, Applied Science Associates (ASA),
NDBC, the University of
Connecticut (UCONN),
and Rutgers University
with funding from the U.S.
IOOS. The CONUS total
vectors are made available
in near real-time via both
graphical display tools, and
machine services Thematic
Real-time Environmental
Distributed Data Services
(THREDDS) to USCG
Environmental Data Server
(EDS). A graphical
representation of the
network is showing in
adjacent figure.
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Direction of Arrival (DOA) Metrics
Detailed analysis into Quality Assurance (QA) metrics is an ongoing research area at CORDC and SIO. Analysis of the compact
antenna patterns and the internal signal processing within the MUSIC algorithm leads to a goodness-of-fit quality metric for the
output radial current velocities and bearings produced by the HF radar system. Quality of measured antenna patterns is
paramount to the accuracy of the MUSIC algorithm bearing output. Ongoing research and development between CORDC and
CODAR Ocean Sensors aims to provide HF radar users with a practical quality metric for the radial current velocities and their
associated bearings produced by the HF radar system.
Our current effort focuses on the three CODAR SeaSonde sites in the San Diego Bight: Point Loma (SDPL), Border Park
(SDBP), and Coronado Island (SDCI). Using the Radial Metric files that CODAR Ocean Sensors developed, we can collect the
statistical distributions of various QA metrics for each site. In this analysis, we are using the maximum of the Direction of Arrival
(DOA) function, the half power width of the DOA function, and the Doppler cell Signal to Noise Ratio (SNR). All of these
metrics are used in determining the bearing angle of each radial velocity vector. See references [5] and [6] for complete details.
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| SeaSonde surface currents maps
for the Malta System San Diego Bight SeaSonde
system baseline analysis.
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The data set currently being analyzed is show in adjacent Figure, which lays out the baseline
areas between SIO SeaSonde sites. If one looks closely, especially on the baseline between
SDBP and SDCI, there are inconsistencies in the radial vectors. Radial velocity vectors are
pointing in both directions, to the northeast, and to the southwest. Physically, this in
unlikely to be a realistic situation. By eliminating the vectors with low quality metrics,
according to the distributions above, it is expected that the baseline data will become more
consistent. As a measure of consistency, the standard deviation of the two components of
the radial velocity vectors (U, V) should decrease after QA analysis. Many days of baseline
data are being analyzed at this time, and formal results will follow.
HF Radar Oil Platform Deployments in
Gulf of Mexico
CORDC staff continue HF radar operations at the Atlantis Platform in the Gulf of Mexico
and an additional radar has just recently been installed on Thunderhorse Platform in August
2012. Processing efforts continue to focus on Loop Current detection using radial currents
from a single radar, and altimeter-derived currents to constrain the single site solutions.
Analysis efforts are prioritized to a time frame when Loop Current passes within close
proximity of the Atlantis radar system. In support of these efforts an array of 14 CORDC
miniature wave buoys were deployed along a transect in the Gulf of Mexico on October
21-22, 2011. The transect extended from the shelf break (~800m depth) to a deep water location
(~2800m depth) that was predicted to be the location of the Loop Current as estimated from satellite imagery and the
EddyWatch product. Within the first 2 weeks of the deployment, 8 of the buoys were entrained in a warm core eddy that was
forming along the Loop Current, while the remaining buoys drifted
along the shelf, and exhibited flow patterns consistent with wind
generated and inertial motions (figure at right). The buoys were
unique in that they captured the warm core eddy during its
formation, and continued to be entrained in the eddy, some making
3 or 4 transits around the eddy. The buoys that made it on to the
shelf provided wave and current observations in the vicinity of many
of BP’s offshore leases. Analysis efforts are continuing on platform
based HF Radar deployments. |
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Track of all buoys over entire deployment
(Oct 2011 - Jan 2012). |
References:
1.) H. Harlan, E. Terrill, H. Hazard, C. Keen et al. The Integrated Ocean Observing
System High-Frequency Radar Network: Status and Local, Regional, and National
Applications, Marine Technology Society Journal, Nov/Dec, Vol 44, No. 6.
2.) S. Y. Kim, E. Terrill, B. Cornuelle, et. al, Mapping the U.S. West Coast surface
circulation: A multiyear analysis of high frequency radar observations, Journal of
Geophysical Research, Vol. 116, C03011, doi:10.1029/2010JC006669, 2011.
3.) E. Terrill, M. Otero, L. Hazard, Mapping Surface Currents Around U.S. Coasts:
A Network of High-Frequency Radar for the Integrated Ocean Observing System,
Sea Technology, September 2007.
4.) E. Terrill, M. Otero, L. Hazard, D. Conlee, J. Harlan, J. Kohut, et. al, Data Management and Real-time Distribution in the HF-Radar National Network,
Oceans 2006.
5.) T. de Paolo, E. Terrill: Skill Assessment of Resolving Ocean Surface Current Structure using Compact-Antenna Style HF RADAR and the MUSIC
Direction Finding Algorithm, American Meteorological Society Journal of Atmospheric and Oceanic Technology, July 2007.
6.) T. de Paolo, E. Terrill: Properties of HF RADAR Compact Antenna Arrays and Their Effect on the MUSIC Algorithm, SIO Library Publications, 2009 http://escholarship.org/uc/item/5bw303tj?query=terrill
All images provided courtesy of Scripps Institution of Oceanography.
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