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Séverine Valerius - 4/05/2017

Ayoub Tamim, 2017 Hubert Curien Thesis Award gold medal winner

Ayoub Tamim, former PhD student from the Geostat project team, receives the 2017 Hubert Curien Thesis Award gold medal for the quality of the work carried out in his thesis entitled "Segmentation and classification of satellite images: application to the detection of Moroccan coastal upwelling zones and implementation of a spatio-temporal monitoring software program".

What does your thesis cover? 

With this thesis work we are focusing on the characterisation and study of the upwelling phenomenon using satellite images of sea surface temperatures. This phenomenon is reflected in a rise in the deep cold coastal waters and with them a significant quantity of nutrients.  This phenomenon is of great interest for many geophysical and oceanographic applications, and it is at the origin of the formation of numerous oceanic structures such as thermal fronts, filaments, meanders and eddies. The aim is to improve the visual interpretations of the images by oceanographers, which often remain subjective. The approach consists in linking detection problems of the thermal structures in upwelling coastal waters to theoretical concepts of computer-aided image and vision processing. In particular, it involves the use of segmentation methods. Moreover, non-linear image processing methods - based on concepts of statistical physics and thermodynamics - have been used to demonstrate oceanographic turbulence characterising the chaotic system of complex marine phenomena. Subsequently, the points of singularity detected in the infrared images, by using microcanonical multifractal formalism, contain key information for understanding these notions of turbulence and oceanic intermittency. 

In what way is it innovative?

Taking into account the chaotic and turbulent nature of the oceanic fluid, we have opted for the detection of the upwelling phenomenon by using image processing methods derived from thermodynamic concepts and which are based on principles originating from the statistical physics of complex and turbulent systems. Our approach essentially uses the notion of singularity exponent (SE) in a microcanonical formulation as well as the exact calculation of these exponents. These exponents enable the accurate detection and identification of the thermal fronts (i.e transition boundaries between masses of cold and warm water) in the sea surface temperature (SST) images, corresponding to the most singular transitions of the signal, i.e to its contours. Indeed, multifractality is a characteristic property of turbulent systems and multifractal formalism is currently the most accurate theoretical physics tool to model turbulent and complex fluid flows. The detection and demonstration of the different thermal structures in the SST images has enabled us to conduct a spatio-temporal analysis of the upwelling activity the length of the Moroccan Atlantic coast and to determine the principal mechanisms controlling its dynamic. Ultimately we have proposed an operational and effective application enabling the analysis and monitoring of the spatial and temporal variability of the upwelling over long time series. 

Why did you choose this thesis subject?

This thesis subject was suggested to me by my supervisor, Driss Aboutajdine, professor of higher education at the Faculty of Science of Rabat, Morocco and, considering my specialism in signal processing during my degree and master's studies, I did not hesitate for one second. 

What does this award represent for you? 

This award represents both a personal honour for the effort made during my years of research and also recognition of the collective work done by several people and components of the LRIT laboratory of the Faculty of Science of Rabat (FSR) and the GeoStat team from the Inria Bordeaux - Sud-Ouest research centre. Getting such success today represents true recognition, especially next to highly renowned pioneering establishments in the field of satellite image processing.  Indeed is the team spirit and the multidisciplinary approach with which, since the start of 2011, we have been conducting an innovative research experiment that must be recognised. The trophy received therefore pays tribute to all of the supervisors and administrative frameworks of the FSR of Rabat and the Inria Bordeaux - Sud-Ouest research centre. 

What are you doing at the moment?

I am currently a teacher-researcher in computer science at the Higher Institute of Maritime Fishing (ISPM) in Agadir, Morocco, and I am also co-founder of a company creating applications for iPhone, iPad and Apple Watch

Keywords: Ayoub Tamim Geostat Award Thesis