Remote Observations of the Spatial Variability of Surface Waves Interacting With an Estuarine Outflow
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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This paper explores the application of phased-array high-frequency HF radars to identify locations of enhanced local wave heights. Measurements of the near-surface current velocities and wave heights were obtained from HF radars deployed near the mouth of the Chesapeake Bay in the fall of 1997. The radar-derived near-surface velocities were compared with the upper bin 2-m depth of four upward-looking acoustic Doppler current profilers ADCPs. The slopes of the linear correlations were close to one and the root-mean-square rms differences were similar to previous studies. Significant wave height Hs estimates from both radars were compared with a laser height gauge. The largest differences were observed during low winds due to overestimates at one of the radar stations and during storms when the laser measurement failed. Further analysis focused on the HF radar results from the more reliable of the two sites. The rms difference between this radar and the in situ sensor was 0.29 m. Synoptic observations of Hs over the Chesapeake Bay revealed regions of current-induced wave shoaling and refraction. Hs over the estuarine outflow increased between 19-50 relative to the incident Hs in light on-shore winds 5 ms. In stronger winds 10 ms, Hs also increased by up to 25 when there was a tidal outflow in the surface layer, although the near-surface currents were responding to both the wind and the ebbing tide.
- Physical and Dynamic Oceanography