During the last decade, satellite microwave sensors such as multichannel scanning radiometers, scatterometers and altimeters have provided extensive time series of upper ocean data. When combined with longer time series from visible and infrared (IR) sensors, the picture of the complexity of upper ocean and coastal zone pro-cesses, and of air-sea-ice interaction, is broadened significantly. Large-scale ocean processes are becoming better understood, leading researchers and modellers to probe further into mesoscale processes (up to 200 krn) where significant energy exchanges and air-sea-ice interactions are occurring. Meandering currents are a dominant feature of many open ocean and coastal waters and often appear in patterns of Sea Surface Temperature (SST) and Chlorophyll a (chl-a) concentration in visible and thermal images acquired by satellite sensors. Furthermore, these currents often develop sharp fronts and eddies that affect wind-wave-current interactions, leading to both wave refraction and small scale surface roughness anomalies. These in turn, provide distinct expressions in both high resolution visible and Synthetic Aperture Radar (SAR) images (Johannessen et al., 2006). SAR backscatter signals come from the sea surface roughness with wavelengths which are approximately similar to the SAR wavelength (between a few to a few of tens centimeter). The roughness is con-trolled by local wind, wave-current interaction, as well as by the presence of surface active films or grease ice.
展开▼
