Evaluating the surface circulation in the Ebro delta (northeastern Spain) with quality-controlled high-frequency radar measurements
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...
Main Authors: | , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2015-11-01
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Series: | Ocean Science |
Online Access: | http://www.ocean-sci.net/11/921/2015/os-11-921-2015.pdf |
Summary: | 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<sup>−1</sup>, 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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ISSN: | 1812-0784 1812-0792 |