Segmentation et classification des images satellitaires : application à la détection des zones d’upwelling côtier marocain et mise en place d’un logiciel de suivi spatiotemporel

摘要

The knowledge of the upwelling systems is very important for many applications in geophysical and oceanographic.The remotely sensed images acquired in real time allow to conduct continuous space maritime monitoring, especially in thermal and visible range, which provide information about the temperature distribution in the sea surface and the ocean colour. In this work, we are interested on the study of the upwelling phenomenon using the sea surface temperature images which is considered to be the origin of the formation of many ocean structures, such as thermal fronts, filaments, meanders and eddies. The main aim is to improve the visual interpretations of the satellite images made by the oceanographers. The proposed approach is based on the segmentation and detection of the thermal mesoscale structures in coastal upwelling waters using several methods in image processing and computer vision. In addition, the images processing methods based on the statistical physics and thermodynamics concepts were also used for the purpose of highlighting the turbulent and complex character of the marine phenomena. In this sense, the singularities points detected in infrared images, using the Microcanonical Multifractal Formalism, contain key information to understandingintermittencyandoceanicturbulence. A computational software system for the calculation of the upwelling index is made available for users in orders to extract and monitor the intensity and extension of upwelling along the Moroccan Atlantic coast. This application allows providing users continually by space synthetic products informing about environmental parameters and permitting to evaluate and to survey the coastal upwelling dynamic in space and time. Finally, a statistical study has been conducted in order to monitor the seasonal variability of the upwelling intensity along the Moroccan Atlantic coast by using well-established upwelling indices and consequently highlight the areas of highupwelling activity.