Ocean Circulation Group
USF College of Marine Science

DISCLAIMER:
The nowcast/forecast system and other analyses/data are research products under development. No warranty is made, expressed or implied, regarding accuracy, or regarding the suitability for any particular application. All rights reserved University of South Florida, Ocean Circulation Group. Copyright University of South Florida 2010

OCG HF Radar


HF Radar Overlay Map


General Background

To improve our understanding of the workings of the coastal ocean for a variety of environmental applications, including hurricane storm surge along the West Coast of Florida, the University of South Florida’s College of Marine Science (USF/CMS) established a real-time Coastal Ocean Monitoring Prediction System (COMPS) for the West Florida Shelf region. COMPS program observing assets consist of arrays of offshore buoys and coastal stations for surface meteorology and in-water measurement of temperature, salinity, currents, and sea level; along with several High Frequency (HF) Radar sites for offshore surface-current velocity field measurements. Commercially available CODAR and WERA HF Radar systems have been in operation for nearly eight years in this challenging region of limited beach availability/access, low wave energy, severe weather, and frequent lightning activity. Along with the coastal ocean observations is a coordinated program of coastal ocean modeling.

Aim

Quantitatively predicting Florida's coastal ocean water properties is dependent on the merging of quality observations with models.  The underpinnings are the coastal ocean circulation since the currents are what deliver nutrients from the deep-ocean and the estuaries to the shelf, thereby fueling primary productivity and initiating the complex biological and chemical interactions resulting in the shelf ecology. Commercial and recreational fisheries depend on this as do blooms of harmful red-tide algae.  Similarly, safe and efficient maritime commerce depends on our ability to specify currents, sea level, and sea state on the basis of the ocean and atmosphere interactions.  Inundation by hurricane storm surge is also matter of great public concern.

Methods

High frequency (HF) radars provide a means for mapping fields of surface velocity vectors by using the Doppler shift in frequency for radio frequency waves scattered off of surface gravity waves.  From these returns a set of radial velocity components is calculated, and given two independent systems, deployed at two different locations along the shoreline, these radial velocity components may be combined to give a field of surface velocity vectors.

Two types of systems are available: either direction finding with a compact antenna system or beam forming with a linear antenna array. Direction finding HF-radars, such as the commercially available CODAR, uses a single transmit antenna and a single receive antenna.  The transmissions are Omni directional, and the receive antenna senses returns along radial directions at fixed angular and radial distances.

Phased array HF-radar, such as the commercially available WERA, uses a 4 antenna transmit array and a 12-16 antenna receive array positioned at close intervals along the beach, to record the backscattered radio wave signals. By virtue of the increased number of antennas, it can operate both in a via direction finding and directional beam forming mode.

Existing USF/CMS Combined CODAR and WERA HF Network

The USF/COMPS/Ocean Circulation Group (OCG) presently operates three long range CODAR systems [Redington Shores, Venice, and Naples, Florida], as well as two WERA systems [Ft De Soto, Venice] on the West Florida Shelf (WFS). The USF CODAR HF-radar systems operate at 4.925 MHz and the WERA HF-radar systems operate between 12.23 – 13.20 MHz, with a higher resolution coverage area within the larger CODAR footprint. The actual WERA transmit frequency and bandwidth is determined by first sweeping the entire FCC licensed operational band prior to each acquisition via WERA’s “Listen before Talk Mode” software to determine the region of lowest noise level and corresponding bandwidth. Hourly data from each site is pulled via scripting to a central processing station located at the University of South Florida/College of Marine Science in St. Petersburg, Florida, where the data is processed and web served.

Redington Shore (RdSr) Site CODAR Notes: The Long Range CODAR site is located at 18200 Gulf Boulevard, Redington Shores, Florida (27° 49.937' N, 82° 50.032' W) within the Pinellas County, Florida Redington Shores Beach Access Park. Offshore sea surface current speed and direction radial data is provided hourly via a cellular phone connection to USF/CMS. Operational on 9/24/03.

Venice (Veni) Site CODAR Notes: The site is located at 1200 South Harbor Drive, Venice, FL (27° 04.655' N, 82° 27.096' W) at the U.S. Coast Guard Auxiliary Station number 86. Offshore sea surface current speed and direction radial data is provided hourly via a dedicated phone/DSL line to USF/CMS. Operational on 4/27/04.

Naples (Napl) Site CODAR Notes: The site is located at 1301 Gulf Shore Boulevard N, Naples, Fl, (26° 09.729' N, 81° 48.632' W) within the City of Naples' Loudermilk Park. Offshore sea surface current speed and direction radial data is provided hourly via a dedicated DSL/phone line to USF/CMS. Initial operation commenced on 12/22/04 with final operation 4/20/05.

Ft De Soto Park/Tierra Verde Site WERA Notes: The 12 RX antenna WERA site is located at the North Beach Pavilion at Ft DeSoto Park (27° 38.16' N, 82° 44.30' W). Offshore sea surface current speed and direction radial data is provided hourly via a cellular phone connection to USF/CMS. This site became operational on 6/05/10.

Venice Site WERA Notes: The 12 RX antenna WERA site is Co-located along with the USF CODAR site at the U.S. Coast Guard Auxiliary Station number 86. Offshore sea surface current speed and direction radial data is provided hourly via cellular modem to USF/CMS. This site became operational on 6/13/10.

Ongoing Discussion/Future Plans

Continuous HF Radar operation on the WFS has had its challenges. After several years of continuous system operation, it became becoming apparent that 5 MHz may not be the optimal choice as an HF Radar operational frequency for the WFS considering its low current/wave climate, frequent lightning related ambient noise effects, and increased traffic in and around the 5 MHz band. For that reason, the operational frequency of the WERA HF sites was set at nominally at 12.7 MHz, with the site locations chosen to be within our existing CODAR HF footprint as shown in Figure 1. This will establish an HF-radar test-bed, focused on the region between Venice and the mouth of Tampa Bay in which we have already begun assessing relative performance between different measurement systems at different frequencies, each overlooking an array of in situ water column velocity measurements by COMPS buoy-mounted ADCPs.

Acknowledgements

The COMPS observing and modeling system has benefited from funding over a variety of sources, beginning with the USGS at its inception, continuing with MMS, ONR and NOAA support, along with that from the State of Florida through USF. The HF-radar network was a contribution by the NOAA funded SECOORA program. WERA equipment additions were through USF internal R&D funds.




In cooperation with



Town Of Redington Shores Florida Pinellas County Florida City of Naple Florida US Coast Guard Auxiliary
Mote Marine Laboratory SECOORA