Meeting Abstracts

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Improving observability of surface currents by HF radars in the oil spill region

Max Yaremchuk, Peter Spence
Naval Research Laboratory
(Abstract received 05/08/2012 for session C)
ABSTRACT

HF radars (HFRs) measure radial velocity components of the surface currents at scales comparable with resolution of regional models, making this type of data especially valuable in monitoring and forecasting tracer transport in coastal regions. HFR data coverage is highly intermittent in space and time due to distortions of the reflected signal by numerous sources of artificial and natural origin. This intermittency may strongly degrade performance of assimilation algorithms and Lagrangian predictability of the surface circulation retrieved from HFR data.

We discuss an improved method of HFR data processing based on the combination of the statistical analysis and 2d variational interpolation (2dVar) technique. At the first stage raw radial velocity data are subject to correlation analysis, which enables to fill gaps in observations and provides estimates of the noise level and integral parameters characterizing small-scale variability of the surface circulation. These parameters are utilized at the second stage, when the cost function for 2dVar scheme is constructed, and the updated gap-free radial velocities are converted into the gridded vector fields.

Preliminary experiments with the HFR data acquired in April-August 2010 near the Deep Water Horizon oil spill demonstrate a potentially significant improvement of the Lagrangian forecast ability compared to the operationally used HFR processing technique.