Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions
"> Figure 1
<p>An example of SeaSonde cross spectra with signal strength in dB from the three antennas, plotted <span class="html-italic">vs.</span> Doppler frequency in Hz. Red: Loop 1, Green: Loop 2, Blue: monopole. The magenta color tic marks indicate the ideal Bragg frequencies and vertical magenta lines mark the calculated first-order boundaries. First-order echo is contained within these boundaries; the higher-order continuum is outside the boundaries. The bronze colored graph is a measure of quality of each Doppler bin. It provides the percentage of the available points over time that were used to calculate each bin. The annotation “%Q” marks 100%.</p> "> Figure 2
<p>Location of the radar sites at North Ronaldsay (NRON) and Sumburgh (SUMB), weather stations at the Sumburgh and Kirkwall airports and the closest UK Met buoy located at 60.70°N, 4.5°W. The buoy, moored in water more than 500 m deep, is 271.2 km from NRON and 201.3km from SUMB. Offshore bathymetry is shown with depths in meters.</p> "> Figure 3
<p>Examples of typical tidal current flow: (<b>a</b>) January 13, 2014, 2:00. The circular segments define the outer limit of the 10th range cells for SUMB and NRON. (<b>b</b>) January 13, 2014, 10:30.</p> "> Figure 4
<p>(<b>a</b>) November 1, 2013, 8:00. The SW wind in the westerly region of the map has caused the NW to SE surface flow to veer to the east. (<b>b</b>) November 2, 2013, 1:30. The SE to NW surface flow is replaced by currents from the SW in the westerly region.</p> "> Figure 4 Cont.
<p>(<b>a</b>) November 1, 2013, 8:00. The SW wind in the westerly region of the map has caused the NW to SE surface flow to veer to the east. (<b>b</b>) November 2, 2013, 1:30. The SE to NW surface flow is replaced by currents from the SW in the westerly region.</p> "> Figure 5
<p>(<b>a</b>) 3 November 2013, 2:30. The wind has changed direction, now coming mostly from the NE. Typical tidal flow has resumed SE→NW. (<b>b</b>) 3 November 2013, 9:30. Slower winds were now mostly from the NE. Typical tidal flow has resumed NW→SE.</p> "> Figure 5 Cont.
<p>(<b>a</b>) 3 November 2013, 2:30. The wind has changed direction, now coming mostly from the NE. Typical tidal flow has resumed SE→NW. (<b>b</b>) 3 November 2013, 9:30. Slower winds were now mostly from the NE. Typical tidal flow has resumed NW→SE.</p> "> Figure 6
<p>Velocity components perpendicular to the baseline between the radar sites, averaged over the area contained within 41km circles (shown in <a href="#remotesensing-06-12094-f003" class="html-fig">Figure 3</a>), centered on SUMB (blue), NRON (black) <span class="html-italic">vs.</span> hours from October 30, 2013, 00:00 UTC.</p> "> Figure 7
<p>(<b>a</b>) Waveheight (<b>b</b>) Wave period (<b>c</b>) Wave directions from range-cell 2 plotted <span class="html-italic">vs.</span> hours from October 30, 2013, 00:00. Blue: SUMB, black: NRON, maroon: Buoy.</p> "> Figure 8
<p>Wind directions plotted <span class="html-italic">vs</span>. hours from 30 October 2013, 00:00: Buoy wind directions: Maroon. (<b>a</b>) Wind directions from integrated first-order energy, Range-cell 2. Blue: SUMB, Black: NRON, (<b>b</b>) Wind directions averaged over the area contained within the 10th SUMB range-cell. Blue: from integrated first-order energy, Green: from wind direction maps. (<b>c</b>) Wind directions averaged over the area contained within the 10th NRON range-cell. Black: from integrated first-order energy, Green: from wind direction maps.</p> "> Figure 9
<p>Current flows near the tidal velocity peaks and troughs showing effects of the strong wind from the SE. (<b>a</b>) January 15, 2014, 8:30 (<b>b</b>) January 15, 2014, 15:30 (<b>c</b>) January 17, 2014, 9:00 (<b>d</b>) January 17, 2014, 17:30.</p> "> Figure 9 Cont.
<p>Current flows near the tidal velocity peaks and troughs showing effects of the strong wind from the SE. (<b>a</b>) January 15, 2014, 8:30 (<b>b</b>) January 15, 2014, 15:30 (<b>c</b>) January 17, 2014, 9:00 (<b>d</b>) January 17, 2014, 17:30.</p> "> Figure 10
<p>The circular pattern flow from NE to NW observed from January 18, 2014, 17:30 for the rest of the time period. These examples are for January 19 near the tidal velocity peaks and troughs (<b>a</b>) 5:30 (<b>b</b>) 8:30 (<b>c</b>) 17:00 (<b>d</b>) 20:00 (no data from Kirkwall at this time).</p> "> Figure 10 Cont.
<p>The circular pattern flow from NE to NW observed from January 18, 2014, 17:30 for the rest of the time period. These examples are for January 19 near the tidal velocity peaks and troughs (<b>a</b>) 5:30 (<b>b</b>) 8:30 (<b>c</b>) 17:00 (<b>d</b>) 20:00 (no data from Kirkwall at this time).</p> "> Figure 11
<p>Velocity components perpendicular to the baseline between the radar sites, averaged over the area contained with the 10th range-cell centered on SUMB (blue), NRON (black) plotted <span class="html-italic">vs.</span> hours from January 13, 2014, 00:00 UTC.</p> "> Figure 12
<p>(<b>a</b>) Waveheight (<b>b</b>) Wave period (<b>c</b>) Wave directions plotted <span class="html-italic">vs.</span> hours from January 13, 2014, 00:00 UTC . Blue: SUMB, black: NRON.</p> "> Figure 13
<p>Black: NRON waveheights; Red: averaged velocity components perpendicular to the baseline plotted <span class="html-italic">vs.</span> hours rom January 13, 2014, 00:00.</p> "> Figure 14
<p>Wind directions plotted <span class="html-italic">vs.</span> hours from January 13, 2014, 00:00. Buoy wind directions: Maroon. (<b>a</b>) Wind directions from integrated first-order energy, Range-cell 2. Blue: SUMB, Black: NRON. (<b>b</b>) Wind directions averaged over the area contained within the 10th SUMB range-cell. Blue: from integrated first-order energy, Green: from wind direction maps. (<b>c</b>) Wind directions averaged over the area contained within the 10th NRON range-cell. Black: from integrated first-order energy, Green: from wind direction maps.</p> "> Figure 14 Cont.
<p>Wind directions plotted <span class="html-italic">vs.</span> hours from January 13, 2014, 00:00. Buoy wind directions: Maroon. (<b>a</b>) Wind directions from integrated first-order energy, Range-cell 2. Blue: SUMB, Black: NRON. (<b>b</b>) Wind directions averaged over the area contained within the 10th SUMB range-cell. Blue: from integrated first-order energy, Green: from wind direction maps. (<b>c</b>) Wind directions averaged over the area contained within the 10th NRON range-cell. Black: from integrated first-order energy, Green: from wind direction maps.</p> ">
Abstract
:1. Introduction
2. Data Sets
3. Methods
3.1. Current Velocity Mapping
3.2. Wave Height, Period and Direction
3.3. Wind Direction Information
3.3.1. Wind Direction from Integrated First-Order Energy
3.3.2. Wind Direction from Radar Echo Amplitudes
4. Results
4.1. Results for October 30, 00:00 to November 3, 23:30, 2013 UTC
4.1.1. Current Velocity and Wind Direction Maps
4.1.2. Wave Height, Period and Direction.
4.1.3. Wind Direction
4.2. Results for January 13, 00:00 to January 19, 23:30, 2014 UTC
4.2.1. Current Velocity and Wind Direction Maps
4.2.2. Wave Height, Period and Direction
4.2.3. Wind Direction
4.3. Discussion
5. Interpretation of Observed Semi-Diurnal Wave Modulations
5.1. Previous Wave-Current Interaction Studies
5.2. Theory of Wave Oscillations
5.3. Comparison of Theory and Observations
5.4. Discussion
6. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References and Notes
- Brahan SeaSonde HF Radar Project. Available online: http://www.thebrahanproject.com/ (access on 3 December 2014).
- Kohut, J; Roarty, H.; Glenn, S. Characterizing observed environmental variability with HF Doppler radar surface current mappers and acoustic Doppler current profilers: Environmental variability in the coastal ocean. IEEE J. Ocean. Eng. 2006, 31, 876–884. [Google Scholar]
- Hubbard, M.; Barrick, D.; Garfield, N.; Pettigrew, J.; Ohlmann, C.; Gough, M. A new method for estimating High-Frequency Radar error using data from Central San Francisco Bay. Ocean Sci. J. 2013, 48, 105–116. [Google Scholar] [CrossRef]
- Ohlmann, C.; White, P.; Washburn, L.; Terrill, E.; Emery, B.; Otero, M. Interpretation of coastal HF Radar-derived surface currents with high-resolution drifter data. J. Atmos. Oceanic Tech. 2006, 24, 666–6802. [Google Scholar] [CrossRef]
- Long, R.; Barrick, D.; Largier, J.; Garfield, N. Wave observations from Central California: SeaSonde systems and in situ wave buoys. J. Sens. 2011. [Google Scholar] [CrossRef]
- Alfonso, D.; Alvarez, E.; Damian Lopez, J. Comparison of CODAR SeaSonde HF Radar Operational Waves and Currents Measurements with Puertos del Estado Buoys. Final Report. 2006. Available online: http://www.codar.com/images/about/2006PDE_final_Report.pdf (access on 3 December 2014).
- Lipa, B.; Barrick, D. Least-squares methods for the extraction of surface currents from CODAR crossed-loop data: Application at ARSLOE. IEEE J. Oceanic Eng. 1983, OE-8, 226–253. [Google Scholar]
- Lipa, B.; Nyden, B.; Ullman, D.; Terrill, E. SeaSonde radial velocities: Derivation and internal consistency. IEEE J. Ocean. Eng. 2006, 31, 850–861. [Google Scholar] [CrossRef]
- Lipa, B.; Nyden, B. Directional wave information from the SeaSonde. IEEE J. Ocean. Eng. 2005, 30, 221–231. [Google Scholar] [CrossRef]
- Lipa, B.; Barrick, D. Extraction of sea state from HF radar sea echo: Mathematical theory and modeling. Radio Sci. 1986, 21, 81–100. [Google Scholar] [CrossRef]
- Fernandez, D.; Graber, H.; Paduan, J.; Barrick, D. Mapping wind direction with HF radar. Oceanography 1997, 10, 93–95. [Google Scholar] [CrossRef]
- Lipa, B.; Nyden, B.; Barrick, D.; Kohut, J. HF radar sea-echo from shallow water. Sensors 2008, 8, 4611–4635. [Google Scholar] [CrossRef]
- Weather History for Sumburgh, UK. Available online: http://www.wunderground.com/history/airport/EGPB/2013/11/3/DailyHistory.html (access on 3 December 2014).
- Weather History for Kirkwall, UK. Available online: http://www.wunderground.com/history/airport/EGPA/2013/11/3/DailyHistory.html (access on 3 December 2014).
- Station 64046—K7 Buoy. Available online: http://www.ndbc.noaa.gov/station_page.php?station=64046 (access on 3 December 2014).
- Longuet-Higgins, M.; Stewart, R. Changes in the form of short gravity waves on long waves and tidal currents. J. Fluid Mech. 1960, 8, 565–583. [Google Scholar] [CrossRef]
- Longuet-Higgins, M.; Stewart, R. Changes in the form of short gravity waves on Steady nonuniform currents. J. Fluid Mech. 1961, 10, 529–549. [Google Scholar] [CrossRef]
- Vincent, C. The interaction of wind-generated sea waves with tidal currents. J. Phys. Oceanogr. 1978, 9, 748–755. [Google Scholar] [CrossRef]
- Tolman, H. The influence of unsteady depths and currents of tides on wind-wave propagation in shelf seas. J. Phys. Oceanogr. 1990, 20, 1166–1174. [Google Scholar] [CrossRef]
- Tolman, H. Effects of tides and storm surges on North Sea wind waves. J. Phys. Oceanogr. 1991, 21, 766–781. [Google Scholar] [CrossRef]
- Phillips, O.M. The Dynamics of the Upper Ocean, 2nd ed.; Cambridge University Press: New York, NY, USA, 1997. [Google Scholar]
- Masson, D. A case study of wave–current interaction in a strong tidal current. J. Phys. Oceanogr. 1996, 26, 359–372. [Google Scholar] [CrossRef]
- Huang, N.; Chen, D.; Tang, C. Interactions between steady nonuniform currents and gravity waves with applications for current measurements. J. Phys. Oceanogr. 1972, 2, 420–431. [Google Scholar] [CrossRef]
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Lipa, B.; Barrick, D.; Alonso-Martirena, A.; Fernandes, M.; Ferrer, M.I.; Nyden, B. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions. Remote Sens. 2014, 6, 12094-12117. https://doi.org/10.3390/rs61212094
Lipa B, Barrick D, Alonso-Martirena A, Fernandes M, Ferrer MI, Nyden B. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions. Remote Sensing. 2014; 6(12):12094-12117. https://doi.org/10.3390/rs61212094
Chicago/Turabian StyleLipa, Belinda, Donald Barrick, Andres Alonso-Martirena, Maria Fernandes, Maria Inmaculada Ferrer, and Bruce Nyden. 2014. "Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions" Remote Sensing 6, no. 12: 12094-12117. https://doi.org/10.3390/rs61212094