Remote sensing of ocean surface currents with the Seasonde HF radar

Hodgins, Donald O.

doi:10.1016/1353-2561(94)90020-5

Cited by 16 publications

(8 citation statements)

References 7 publications

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“…It is possible that variations in the outflow depth h o can account for this difference but we cannot easily test this. However it should be noted that the Fraser plume, with its short residence time [ Pawlowicz et al , 2007], is not really in steady state [see also Hodgins et al , 1994], so the rotating bulge idealization may not be as useful as it is in other situations [e.g., Chant et al , 2008].…”

Section: Discussionmentioning

confidence: 99%

Estuarine forcing of a river plume by river flow and tides

Halverson¹,

Pawlowicz²

2008

J. Geophys. Res.

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[1] Estuarine forcing of a river plume by river discharge and tides is examined with a novel data set capable of characterizing semidiurnal to annual time scales. An instrumented ferry made high-resolution salinity measurements as it crossed the Fraser River plume, British Columbia, Canada, eight times per day over the years [2003][2004][2005][2006]. The relative contribution of different forcing factors in controlling the river plume salinity and surface area is examined over the full range of time scales. A Lomb-Scargle periodogram of the plume salinity shows energy concentrated in the semidiurnal and diurnal tidal bands. Diurnal lines contain more energy relative to semidiurnal lines than the respective tidal constituents would suggest. At fortnightly frequencies, local maxima in plume salinity coincide with periods of maxima in daily tidal height, with no phase shift. Thus the estuary adjusts quickly to changes in forcing. The effectiveness of tides in setting the plume salinity is a function of river discharge and is greatest when the river discharge is high and minimal when the river discharge is low. Tidal effects are superimposed onto the longperiod river discharge cycle. At time scales of 25 days or longer, the mean river plume salinity decreases quasi-linearly with increasing river discharge, but the change in salinity with river discharge is instantaneous to within the sampling resolution. Plume surface area increases with river discharge, from 200-500 km 2 at low river flow to 1000-1500 km 2 at high river flow. The magnitude of the surface area is predicted well by scaling the mouth deformation radius.Citation: Halverson, M. J., and R. Pawlowicz (2008), Estuarine forcing of a river plume by river flow and tides,

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Section: Discussionmentioning

confidence: 99%

Estuarine forcing of a river plume by river flow and tides

Halverson¹,

Pawlowicz²

2008

J. Geophys. Res.

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“…In recent years, HF radar systems for current measurements (Barrick et al 1985;Gurgel et al 1999b), such as the SeaSonde (Hodgins 1994) or Wellen Radar (WERA; Gurgel et al 1999a) have been used throughout the world, mainly to study coastal circulation. Most of these systems operate at a frequency of around 24 MHz or lower, observing from a few tens of kilometers up to more than a hundred kilometers, at a resolution of a few kilometers.…”

Section: B Current Measurements By Hf Radarmentioning

confidence: 99%

On the Probability and Spatial Distribution of Ocean Surface Currents

Ashkenazy

Gildor

2011

Journal of Physical Oceanography

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Insights into the probability distribution of ocean currents are important for various applications such as the chance to encounter extreme events, which may affect, for example, marine construction, and for estimating the energy that can be extracted from the ocean. In addition, for devising better parameterizations for submesoscale mixing, which present climate models cannot resolve, one should understand the velocity distribution and its relation to the various forcing of surface ocean circulation. Here, the authors investigate the probability distribution of surface currents from the Gulf of Eilat/Aqaba measured by high-frequency radar. Their results show that the distribution of ocean current speeds can be approximated by a Weibull distribution. Moreover, the authors demonstrate the existence of spatial variations of the scale and shape parameters of the Weibull distribution over a relatively small region of only a few kilometers. They use a simple surface Ekman layer model to investigate this spatial variability. They find that, when forced by local winds, this model does not reproduce the observations. The addition of Gaussian noise to the zonal and meridional components of the bottom geostrophic currents has only a slight effect on the surface current distribution. However, noise added to the components of the local wind (mimicking wind gusts) has a much greater effect on the distribution of surface currents, suggesting that wind spatial and temporal variability underlay the observed spatial variability of the parameters of the Weibull distribution.

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“…Increasingly accurate remote sensing techniques are available for measuring surface currents in coastal areas [ Barrick et al , 1985; Gurgel et al , 1999b]. High‐frequency (HF) radar stations measuring surface currents, such as the SeaSonde [ Hodgins , 1994] or WERA [ Gurgel et al , 1999a] flourish along shorelines worldwide. On the basis of Bragg resonance from ocean waves and the Doppler shift in the reflected signal, the HF radar station is able to determine the magnitude of the surface current along a radial joining the antenna and any target point [ Barrick et al , 1977].…”

Section: Introductionmentioning

confidence: 99%

Computation and approximation of the length scales of harmonic modes with application to the mapping of surface currents in the Gulf of Eilat

Lekien

Gildor

2009

J. Geophys. Res.

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[1] Open-boundary modal analysis (OMA) is a generalized Fourier transform that interpolates, extrapolates, and filters scattered current measurements and produces smooth current maps in coastal areas. Boundary conditions are enforced by adjusting the OMA modes to the coastline. Filtering is achieved by discarding OMA modes whose length scales are below a selected threshold. In this paper, we determine the length scale of the OMA modes, and we derive approximated formulas. Operational use of the OMA modes and the length scale formulas are illustrated on surface currents measured by highfrequency radar in the Gulf of Eilat (Gulf of Aqaba).Citation: Lekien, F., and H. Gildor (2009), Computation and approximation of the length scales of harmonic modes with application to the mapping of surface currents in the Gulf of Eilat,

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Remote sensing of ocean surface currents with the Seasonde HF radar

Cited by 16 publications

References 7 publications

Estuarine forcing of a river plume by river flow and tides

Estuarine forcing of a river plume by river flow and tides

On the Probability and Spatial Distribution of Ocean Surface Currents

Computation and approximation of the length scales of harmonic modes with application to the mapping of surface currents in the Gulf of Eilat

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