scholarly journals Assessment of CODAR SeaSonde and WERA HF Radars in Mapping Surface Currents on the West Florida Shelf*

2014 ◽  
Vol 31 (6) ◽  
pp. 1363-1382 ◽  
Author(s):  
Yonggang Liu ◽  
Robert H. Weisberg ◽  
Clifford R. Merz
Keyword(s):  
Radial Velocity ◽  
Long Range ◽  
Hf Radar ◽  
Integration Time ◽  
Surface Currents ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
Radar Systems ◽  
Effective Depth

Abstract Concurrently operated on the West Florida shelf for the purpose of observing surface currents are three long-range (4.9 MHz) Coastal Ocean Dynamics Applications Radar (CODAR) SeaSonde and two median-range (12.7 MHz) Wellen Radar (WERA) high-frequency (HF) radar systems. These HF radars overlook an array of moored acoustic Doppler current profilers (ADCPs), three of which are presently within the radar footprint. Analyzed herein are 3 months of simultaneous observations. Both the SeaSonde and WERA systems generally agree with the ADCPs to within root-mean-square differences (rmsd) for hourly radial velocity components of 5.1–9.2 and 3.8–6.5 cm s−1 for SeaSonde and WERA, respectively, and within rmsd for 36-h low-pass filtered radial velocity components of 2.8–6.0 and 2.2–4.3 cm s−1 for SeaSonde and WERA, respectively. The bearing offset and tidal and subtidal currents of total velocities are also assessed using the ADCP data. Despite differences in a variety of aspects between the direction-finding CODAR SeaSonde (long range, effective depth of 2.4 m, integration time of 4 h, and idealized antenna patterns) and the beam-forming WERA (median range, effective depth of 0.9 m, and integration time of 1 h), both HF radar systems demonstrated good surface current mapping capability. The differences between the velocities measured with the HF radar and the ADCP are sufficiently small in this low-energy shelf that much of these rmsd values may be accounted for by the expected measurement differences due to the horizontal, vertical, and temporal sampling differences of the ocean current observing systems used.

High-Frequency Radar Mapping of Surface Currents Using WERA

2007 ◽  
Vol 24 (3) ◽  
pp. 484-503 ◽  
Author(s):  
Lynn K. Shay ◽  
Jorge Martinez-Pedraja ◽  
Thomas M. Cook ◽  
Brian K. Haus ◽  
Robert H. Weisberg
Keyword(s):  
Time Series ◽  
High Frequency ◽  
Tidal Currents ◽  
Tropical Storm ◽  
Surface Velocity ◽  
Surface Currents ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
East West

Abstract A dual-station high-frequency Wellen Radar (WERA), transmitting at 16.045 MHz, was deployed along the west Florida shelf in phased array mode during the summer of 2003. A 33-day, continuous time series of radial and vector surface current fields was acquired starting on 23 August ending 25 September 2003. Over a 30-min sample interval, WERA mapped coastal ocean currents over an ≈40 km × 80 km footprint with a 1.2-km horizontal resolution. A total of 1628 snapshots of the vector surface currents was acquired, with only 70 samples (4.3%) missing from the vector time series. Comparisons to subsurface measurements from two moored acoustic Doppler current profilers revealed RMS differences of 1 to 5 cm s−1 for both radial and Cartesian current components. Regression analyses indicated slopes close to unity with small biases between surface and subsurface measurements at 4-m depth in the east–west (u) and north–south (υ) components, respectively. Vector correlation coefficients were 0.9 with complex phases of −3° and 5° at EC4 (20-m isobath) and NA2 (25-m isobath) moorings, respectively. Complex surface circulation patterns were observed that included tidal and wind-driven currents over the west Florida shelf. Tidal current amplitudes were 4 to 5 cm s−1 for the diurnal and semidiurnal constituents. Vertical structure of these tidal currents indicated that the semidiurnal components were predominantly barotropic whereas diurnal tidal currents had more of a baroclinic component. Tidal currents were removed from the observed current time series and were compared to the 10-m adjusted winds at a surface mooring. Based on these time series comparisons, regression slopes were 0.02 to 0.03 in the east–west and north–south directions, respectively. During Tropical Storm Henri’s passage on 5 September 2003, cyclonically rotating surface winds forced surface velocities of more than 35 cm s−1 as Henri made landfall north of Tampa Bay, Florida. These results suggest that the WERA measured the surface velocity well under weak to tropical storm wind conditions.

scholarly journals HF Radar Performance in a Low-Energy Environment: CODAR SeaSonde Experience on the West Florida Shelf*

2010 ◽  
Vol 27 (10) ◽  
pp. 1689-1710 ◽  
Author(s):  
Yonggang Liu ◽  
Robert H. Weisberg ◽  
Clifford R. Merz ◽  
Sage Lichtenwalner ◽  
Gary J. Kirkpatrick
Keyword(s):  
Coastal Ocean ◽  
Low Energy ◽  
Ocean Dynamics ◽  
Hf Radar ◽  
Limiting Factors ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
Significant Wave ◽  
Energy Environment

Abstract Three long-range (5 MHz) Coastal Ocean Dynamics Application Radar (CODAR) SeaSonde HF radars overlooking an array of as many as eight moored acoustic Doppler current profilers (ADCPs) have operated on the West Florida Shelf since September 2003 for the purpose of observing the coastal ocean currents. HF radar performance on this low-energy (currents and waves) continental shelf is evaluated with respect to data returns, the rms differences between the HF radar and the ADCP radial currents, bearing offsets, and radial velocity uncertainties. Possible environmental factors affecting the HF radar performance are discussed, with the findings that both the low-energy sea state and the unfavorable surface wave directions are the main limiting factors for these HF radar observations of currents on the WFS. Despite the challenge of achieving continuous backscatter from this low-energy environment, when acquired the data quality is good in comparison with the ADCP measurements. The rms differences range from 6 to 10 cm s−1 for hourly and from 3 to 6 cm s−1 for 36-h low-pass-filtered radial currents, respectively. Bearing offsets are in the range from −15° to +9°. Coherent variations of the HF radar and ADCP radial currents are seen across both tidal and subtidal frequency bands. By examining the HF radar radial velocities at low wave energy, it is found that the data returns decrease rapidly for significant wave heights smaller than 1 m, and that the rms differences between the HF radar and ADCP radials are degraded when the significant wave height is smaller than 0.3 m.

Comparison of the X-TRACK altimetry estimated currents with moored ADCP and HF radar observations on the West Florida Shelf

2012 ◽  
Vol 50 (8) ◽  
pp. 1085-1098 ◽  
Author(s):  
Yonggang Liu ◽  
Robert H. Weisberg ◽  
Stefano Vignudelli ◽  
Laurent Roblou ◽  
Clifford R. Merz
Keyword(s):  
Hf Radar ◽  
West Florida Shelf ◽  
The West ◽  
Radar Observations ◽  
Florida Shelf

scholarly journals Current Patterns on the West Florida Shelf from Joint Self-Organizing Map Analyses of HF Radar and ADCP Data

2007 ◽  
Vol 24 (4) ◽  
pp. 702-712 ◽  
Author(s):  
Yonggang Liu ◽  
Robert H. Weisberg ◽  
Lynn K. Shay
Keyword(s):  
Hf Radar ◽  
Ocean Current ◽  
Self Organizing Map ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
Buoyancy Forcing ◽  
Temporal Structures ◽  
Self Organizing

Abstract To assess the spatial structures and temporal evolutions of distinct physical processes on the West Florida Shelf, patterns of ocean current variability are extracted from a joint HF radar and ADCP dataset acquired from August to September 2003 using Self-Organizing Map (SOM) analyses. Three separate ocean–atmosphere frequency bands are considered: semidiurnal, diurnal, and subtidal. The currents in the semidiurnal band are relatively homogeneous in space, barotropic, clockwise polarized, and have a neap-spring modulation consistent with semidiurnal tides. The currents in the diurnal band are less homogeneous, more baroclinic, and clockwise polarized, consistent with a combination of diurnal tides and near-inertial oscillations. The currents in the subtidal frequency band are stronger and with more complex patterns consistent with wind and buoyancy forcing. The SOM is shown to be a useful technique for extracting ocean current patterns with dynamically distinctive spatial and temporal structures sampled by HF radar and supporting in situ measurements.

An HF-radar test deployment amidst an ADCP array on the West Florida Shelf

2004 ◽  
Author(s):  
F.J. Kelly ◽  
J.S. Bonner ◽  
J.C. Perez ◽  
J.S. Adams ◽  
D. Prouty ◽  
...  
Keyword(s):  
Hf Radar ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf

USGS field activity 09FSH02 on the west Florida shelf, Gulf of Mexico, in August 2009

Data Series ◽  
2009 ◽  
Author(s):  
Lisa L. Robbins ◽  
Paul O. Knorr ◽  
Xuewu Liu ◽  
Robert H. Byrne ◽  
Ellen A. Raabe
Keyword(s):  
Gulf Of Mexico ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
Field Activity

USGS Field Activities 11CEV01 and 11CEV02 on the West Florida Shelf, Gulf of Mexico, in January and February 2011

Data Series ◽  
10.3133/ds711 ◽  
2014 ◽  
Author(s):  
Lisa L. Robbins ◽  
Paul O. Knorr ◽  
Kendra L. Daly ◽  
Carl A. Taylor
Keyword(s):  
Gulf Of Mexico ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf

scholarly journals A loop current-induced jet along the edge of the West Florida Shelf

1999 ◽  
Vol 26 (15) ◽  
pp. 2239-2242 ◽  
Author(s):  
Robert D. Hetland ◽  
Ya Hsueh ◽  
Robert R. Leben ◽  
Pearn P. Niiler
Keyword(s):  
Loop Current ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf
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