Thursday, 18 July 2002
Observation of atmospheric boundary layer and turbulence activity over the ocean surface using synthetic aperture radar
Atmospheric processes can often produce identifiable signatures in satellite synthetic aperture radar (SAR) imagery of the ocean surface. The most common atmospheric features imaged by SAR over the oceans are wind speed variability patterns ranging from simple wind fronts to well-defined mesoscale circulation features. Variations in the wind stress produce variations in sea surface roughness (Bragg waves height and distribution) and, thus, on the overall backscatter received by the radar. A region of higher wind speeds would tend to exhibit brighter radar return than a region of lower wind speeds. In effect, any atmospheric process that produces wind speed variability at the marine atmospheric boundary layer (MABL) can potentially generate an observable SAR signature. These processes may include atmospheric internal gravity waves (AGW), atmospheric roll vortices (also know as organized large eddies (OLE) or wind rows), cloud streets, vortex streets, and convective cell activity. A review of these SAR signatures and there potential application to boundary layer and turbulence research is provided. In particular, the ability of SAR to detect these features is explored against associated cloud pattern observations typically obtained using visible and thermal satellite sensors.
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