Constraining energetic slope currents through assimilation of high-frequency radar observations

A. K. Sperrevik, K. H. Christensen, J. Röhrs
2015 Ocean Science (OS)  
<p><strong>Abstract.</strong> Assimilation of high-frequency (HF) radar current observations and CTD hydrography is performed with the 4D-Var analysis scheme implemented in the Regional Ocean Modeling System (ROMS). We consider both an idealized case, with a baroclinic slope current in a periodic channel, and a realistic case for the coast of Vesterålen in northern Norway. In the realistic case, the results of the data assimilation are compared with independent data from acoustic profilers and
more » ... stic profilers and surface drifters. Best results are obtained when background error correlation scales are small (10 km or less) and when the data assimilation window is short, i.e. about 1 day. Furthermore, we find that the impact of assimilating HF radar currents is generally larger than the impact of CTD hydrography. However, combining the HF radar currents with a few hydrographic profiles gives significantly better results, which demonstrates the importance of complementing surface observations with observations of the vertical structure of the ocean.</p>
doi:10.5194/os-11-237-2015 fatcat:yjordh7ugjgttgqgwfqtjai6my