Variability in the air–sea interaction patterns and timescales within the south-eastern Bay of Biscay, as observed by HF radar data

Abstract. Two high-frequency (HF) radar stations were installed on the coast of the south-eastern Bay of Biscay in 2009, providing high spatial and temporal resolution and large spatial coverage of currents in the area for the first time. This has made it possible to quantitatively assess the air–sea interaction patterns and timescales for the period 2009–2010. The analysis was conducted using the Barnett–Preisendorfer approach to canonical correlation analysis (CCA) of reanalysis surface winds and HF radar-derived surface currents. The CCA yields two canonical patterns: the first wind–current interaction pattern corresponds to the classical Ekman drift at the sea surface, whilst the second describes an anticyclonic/cyclonic surface circulation. The results obtained demonstrate that local winds play an important role in driving the upper water circulation. The wind–current interaction timescales are mainly related to diurnal breezes and synoptic variability. In particular, the breezes force diurnal currents in waters of the continental shelf and slope of the south-eastern Bay. It is concluded that the breezes may force diurnal currents over considerably wider areas than that covered by the HF radar, considering that the northern and southern continental shelves of the Bay exhibit stronger diurnal than annual wind amplitudes.

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Variability in the air–sea interaction patterns and time-scales within the Southeastern Bay of Biscay, as observed by HF radar data

Ocean Science Discussions ◽

10.5194/osd-9-2793-2012 ◽

2012 ◽

Vol 9 (4) ◽

pp. 2793-2815

Author(s):

A. Fontán ◽

G. Esnaola ◽

J. Sáenz ◽

M. González

Keyword(s):

Time Scales ◽

Radar Data ◽

Hf Radar ◽

Bay Of Biscay ◽

Interaction Patterns ◽

Synoptic Variability ◽

Continental Shelves ◽

Surface Circulation ◽

Spatial Coverage ◽

Current Interaction

Abstract. Two high frequency (HF) radar stations were installed on the Southeastern Bay of Biscay in 2009, providing high spatial and temporal resolution and large spatial coverage currents for the first time in the area. This has enabled to determine quantitatively the air–sea interaction patterns and time-scales for the period 2009–2010. The analysis was conducted by using the Barnett-Preisendorfer approach to canonical correlation analysis (CCA) of reanalysis surface winds and HF radar-derived currents. The results reveal that the CCA yields two canonical patterns. The first wind-current interaction pattern corresponds to the classical Ekman drift at sea surface, whilst the second describes an anticyclonic/cyclonic surface circulation. The results obtained demonstrate that the local winds play an important role in driving the upper water circulation. The wind-current interaction time-scales are mainly related to diurnal breezes and synoptic variability. In particular, the breezes force diurnal currents in the continental shelf and slope of the Southeastern Bay. It is concluded that the breezes may force diurnal currents over considerably wider areas than that covered by the HF radar, considering that the northern and southern continental shelves of the Bay exhibit stronger diurnal than annual wind amplitudes.

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Surface circulation and Lagrangian transport in the SE Bay of Biscay from HF radar data

2013 MTS/IEEE OCEANS - Bergen ◽

10.1109/oceans-bergen.2013.6608039 ◽

2013 ◽

Cited By ~ 3

Author(s):

Anna Rubio ◽

Lohitzune Solabarrieta ◽

Manuel Gonzalez ◽

Julien Mader ◽

Sonia Castanedo ◽

...

Keyword(s):

Radar Data ◽

Hf Radar ◽

Bay Of Biscay ◽

Lagrangian Transport ◽

Surface Circulation

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Gap Filling of the CALYPSO HF Radar Sea Surface Current Data through Past Measurements and Satellite Wind Observations

International Journal of Navigation and Observation ◽

10.1155/2016/2605198 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

Adam Gauci ◽

Aldo Drago ◽

John Abela

Keyword(s):

Oil Spills ◽

Surface Current ◽

Radar Data ◽

Current Data ◽

Hf Radar ◽

Sea Surface ◽

Machine Learning Techniques ◽

Learning Techniques ◽

Spatial Coverage ◽

Essential Components

High frequency (HF) radar installations are becoming essential components of operational real-time marine monitoring systems. The underlying technology is being further enhanced to fully exploit the potential of mapping sea surface currents and wave fields over wide areas with high spatial and temporal resolution, even in adverse meteo-marine conditions. Data applications are opening to many different sectors, reaching out beyond research and monitoring, targeting downstream services in support to key national and regional stakeholders. In the CALYPSO project, the HF radar system composed of CODAR SeaSonde stations installed in the Malta Channel is specifically serving to assist in the response against marine oil spills and to support search and rescue at sea. One key drawback concerns the sporadic inconsistency in the spatial coverage of radar data which is dictated by the sea state as well as by interference from unknown sources that may be competing with transmissions in the same frequency band. This work investigates the use of Machine Learning techniques to fill in missing data in a high resolution grid. Past radar data and wind vectors obtained from satellites are used to predict missing information and provide a more consistent dataset.

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Evaluating the surface circulation in the Ebro delta (northeastern Spain) with quality-controlled high-frequency radar measurements

Ocean Science ◽

10.5194/os-11-921-2015 ◽

2015 ◽

Vol 11 (6) ◽

pp. 921-935 ◽

Cited By ~ 15

Author(s):

P. Lorente ◽

S. Piedracoba ◽

J. Soto-Navarro ◽

E. Alvarez-Fanjul

Keyword(s):

High Frequency ◽

Marine Protected Area ◽

Accuracy Assessment ◽

Surface Current ◽

Radar Data ◽

Western Mediterranean ◽

Hf Radar ◽

Ebro Delta ◽

Ebro River ◽

Surface Circulation

Abstract. The Ebro River delta is a relevant marine protected area in the western Mediterranean. In order to promote the conservation of its ecosystem and support operational decision making in this sensitive area, a three-site standard-range (13.5 MHz) CODAR SeaSonde high-frequency (HF) radar was deployed in December 2013. The main goal of this work is to explore basic features of the sea surface circulation in the Ebro deltaic region as derived from reliable HF radar surface current measurements. For this aim, a combined quality control methodology was applied: firstly, 1-year long (2014) real-time web monitoring of nonvelocity-based diagnostic parameters was conducted to infer both radar site status and HF radar system performance. The signal-to-noise ratio at the monopole exhibited a consistent monthly evolution, although some abrupt decreases (below 10 dB), occasionally detected in June for one of the radar sites, impacted negatively on the spatiotemporal coverage of total current vectors. It seemed to be sporadic episodes since radar site overall performance was found to be robust during 2014. Secondly, a validation of HF radar data with independent in situ observations from a moored current meter was attempted for May–October 2014. The accuracy assessment of radial and total vectors revealed a consistently high agreement. The directional accuracy of the HF radar was rated at better than 8°. The correlation coefficient and root mean square error (RMSE) values emerged in the ranges [0.58–0.83] and [4.02–18.31] cm s−1, respectively. The analysis of the monthly averaged current maps for 2014 showed that the HF radar properly represented basic oceanographic features previously reported, namely, the predominant southwestward flow, the coastal clockwise eddy confined south of the Ebro delta mouth, or the Ebro River impulsive-type freshwater discharge. The EOF analysis related the flow response to local wind forcing and confirmed that the surface current field evolved in space and time according to three significantly dominant modes of variability.

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Temperature and salinity variability in the south-eastern corner of the Bay of Biscay (NE Atlantic)

Journal of Marine Systems ◽

10.1016/j.jmarsys.2012.02.010 ◽

2013 ◽

Vol 109-110 ◽

pp. S105-S120 ◽

Cited By ~ 6

Author(s):

R. Somavilla ◽

C. González-Pola ◽

A. Lavín ◽

C. Rodriguez

Keyword(s):

Bay Of Biscay ◽

Ne Atlantic ◽

The South ◽

South Eastern ◽

Salinity Variability

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Planktic foraminiferal production along an offshore–onshore transect in the south-eastern Bay of Biscay

Continental Shelf Research ◽

10.1016/j.csr.2008.12.021 ◽

2009 ◽

Vol 29 (8) ◽

pp. 1123-1135 ◽

Cited By ~ 18

Author(s):

S. Retailleau ◽

H. Howa ◽

R. Schiebel ◽

F. Lombard ◽

F. Eynaud ◽

...

Keyword(s):

Bay Of Biscay ◽

The South ◽

South Eastern

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Geopotential Topographies and Associated Circulation in the South-Eastern Indian Ocean

Marine and Freshwater Research ◽

10.1071/mf9620001 ◽

1962 ◽

Vol 13 (1) ◽

pp. 1 ◽

Cited By ~ 15

Author(s):

K Wyrtki

Keyword(s):

Indian Ocean ◽

Internal Waves ◽

Eastern Indian Ocean ◽

Surface Currents ◽

The South ◽

The West ◽

South Eastern ◽

South West ◽

Surface Circulation ◽

Current Systems

Geopotential topographies of the surface and several subsurface depths are drawn from the observations on three cruises of H.M.A.S. Diamantina in the waters to the west and south of Australia in 1959 and 1960. The associated circulation is discussed. Surface circulation is found to be in general agreement with the observed surface currents. The subsurface flow between 300 and 1200 m depth indicates an entry of water from the south across 32� S. which turns to the west south of 20� S. Transports in certain current systems and eddies are calculated. The importance of internal waves in the south-west of the region, having amplitudes of more than 100 m, is discussed.

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Review of "Joint analysis of coastal altimetry and HF radar data: observability of seasonal and mesoscale ocean dynamics in the Bay of Biscay"

10.5194/os-2018-33-rc1 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Radar Data ◽

Ocean Dynamics ◽

Hf Radar ◽

Joint Analysis ◽

Bay Of Biscay

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Direction Finding and Likelihood Ratio Detection for Oceanographic HF Radars

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-21-0110.1 ◽

2021 ◽

Author(s):

Anthony Kirincich ◽

Libe Washburn

Keyword(s):

Likelihood Ratio ◽

Correlation Coefficients ◽

Likelihood Estimation ◽

Radar Data ◽

Hf Radar ◽

Estimation Methods ◽

Spatial Coverage ◽

Similar Accuracy ◽

The Cost ◽

Improved Accuracy

Abstract Previous work with simulations of oceanographic HF radars has identified possible improvements when using Maximum Likelihood Estimation (MLE) for directional-of-arrival (DOA), however methods for determining the number of emitters (here defined as spatially distinct patches of the ocean surface) have not realized these improvements. Here we describe and evaluate the use of the Likelihood Ratio (LR) for emitter detection, demonstrating its application to oceanographic HF radar data. The combined detection-estimation methods MLE-LR are compared with MUSIC and MUSIC parameters for SeaSonde HF radars, along with a method developed for 8-channel systems known as MUSIC-Highest. Results show that the use of MLE-LR produces similar accuracy in terms of the RMS difference and correlation coefficients squared, as previous methods. We demonstrate that improved accuracy can be obtained for both methods, at the cost of fewer velocity observations and decreased spatial coverage. For SeaSondes, accuracy improvements are obtained with less commonly used parameter sets. The MLE-LR is shown to be able to resolve simultaneous closely spaced emitters, which has the potential to improve observations obtained by HF radars operating in complex current environments.

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