HF Radar wave-spectrum assimilation using SWAN and application for the Chesapeake Bay Mouth
Abstract
Spectral wave models such as SWAN (Simulating WAves Nearshore) can provide local high-resolution wave forecast fields. These forecasts are often inadequately constrained by observational data. The assimilation of wave observations from high-frequency (HF) radar sites can result in increased forecast fidelity. In order to assimilate HF radar wave observations into SWAN, a forward model for the HF Doppler spectrum, based on first- and second-order Bragg scattering, was developed. This model uses the spatially varying wave spectra computed using the SWAN model, forecast currents from the Navy Coastal Ocean Model (NCOM), and HF radar system parameters to predict time-varying range-Doppler maps for stations of interest. Using an adjoint of the HF radar model, the error between these predictions and the corresponding HF Doppler spectrum observations can be translated into effective wave-spectrum errors for assimilation in the SWAN model.
Initial testing for this system was conducted using data collected at ten HF radar sites in the Southern California Bight during the CASPER-West experiment in October 2017. Here we extend the system to an additional domain centered on the Mouth of the Chesapeake Bay. We will examine results from three HF radar sites during August 2017. The freshwater outflow, variable winds and complex bathymetry make for a challenging application and will extend the utility of this system. Supported by Office of Naval Research Contract No. N00014-17-C-7021.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA250...06B
- Keywords:
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- 3315 Data assimilation;
- ATMOSPHERIC PROCESSES;
- 0520 Data analysis: algorithms and implementation;
- COMPUTATIONAL GEOPHYSICS