Studies of Sub-Mesoscale Variability of the Ocean Upper Layer Based on Satellite Observations Data

Abstract

Purpose. The approach represented in the article is applied to analysis of satellite scanner optical images of high spatial resolution for identifying and quantitative determining the characteristics of the sub-mesoscale dynamic processes in the ocean upper layer. Methods and Results. The Envisat AATSR and MERIS SAR-images are used as the satellite data, which permit to determine the ocean surface temperature and surface brightness in the visible range, respectively. Variations in the sea surface glitter contrasts are associated with modulations of the sea surface roughness (rms slope of short waves) on the currents. It is shown that the surface roughness contrasts correlate with the spatial inhomogeneities of the ocean surface temperature, tracing sub-mesoscale processes in the ocean (spiral eddies, filaments, local shears of currents). The described model of formation of surface manifestations is based on interaction between the Ekman current and the main flow vorticity. Conclusions. Possibility of detecting and quantitative assessing the intense current gradients in the vicinity of sub-mesoscale fronts is shown. These gradients are manifested in the optical satellite images through the ocean surface roughness modulations. The proposed approach makes it possible to study and to assess quantitatively the dynamic processes taking place in the vicinity of the sub-mesoscale fronts. These processes, in their turn, affect the exchange of momentum, heat and gases between the ocean and the atmosphere. The prospects of applying the sub-mesoscale variability defined from the satellite measurements, to development of the models and the systems for the ocean global observations and monitoring are discussed