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| Version 2013-2014 |
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| OCEA0059-1 | Remote Sensing of the Oceans
- Introduction to satellite oceanography
- Advanced satellite oceanography
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| Duration : | Introduction to satellite oceanography : 15h Th, 15h Pr
Advanced satellite oceanography : 15h Th, 15h Pr
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| Number of credits : |
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| Lecturer : | Introduction to satellite oceanography : Yves Cornet
Advanced satellite oceanography : Yves Cornet
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| Coordinator : | N... |
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Language(s) of instruction :
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| English language |
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Course contents :
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 | | Introduction to satellite oceanography |
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| As this course is geared towards students with very different technical and scientific backgrounds, its goal will be to provide a common theoretical ground of general concepts used in the processing of digital images recorded by satellite sensors. We have decided to concentrate our programme on these aspects because satellite oceanography is a very broad field of study, dealing with the observation of water bodies using sensors that detect visible light, reflective infrared, thermal infrared, and microwaves (hyperfrequencies - RADAR imagers). These sensors can also be considered as amospheric sounders or imagers.
The atmospheric sounders are often used to identify the weather conditions in order to model radiative transfers through the atmosphere. Processing data from such atmospheric sensors requires advanced knowledge in atmospheric and aerosol physics. Another field of satellite oceanography aims at defining a geoid model and measuring the sea surface height above/below this reference geoid, while filtering disruptive effects (waves, tides, etc.). This is achieved by applying advanced concepts of geodesy, analysing the satellites' trajectories using their height measurements as provided by altimeters (e.g. RADAR altimeters) and their position and attitude as provided by orbital positioning systems (e.g. DORIS) and by inertial measurement units (IMU) or star trackers. In addition, the processing of data acquired using e.g. SAR systems, which provide a phase and an amplitude, calls upon complex theoretical notions of signal processing.
This is why, for the introductory course, we have chosen to only study the data produced by image sensors that detect visible light and infrared. As this course is aimed at oceanologists and limnologists, it will be illustrated by examples that are specifically related to these fields of research. In addition, as the data acquired is geolocalised, we will also explain general concepts of digital and mathematical cartography and spatial analysis, which are essential in order to analyse the data.
Whether the images are used to observe land, lakes, seas or oceans, and whether the phenomena studied are physical, biological or anthropic, it is essential that students learn the general theory of image processing, regardless of spatial and time aspects (or geographical aspects). This is what the theoretical part of the course focuses on. Most of these concepts are applied through the use of software tools during the supervised practical part of the course.
The course's general outline is as follows:
I. Introduction
1. Definition
2. Brief history
3. Satellite movements
4. Nature of the signal
5. Some satellites and sensors
II. Monogenic image processing
6. Concept of digital image
7. Monogenic image visualisation
8. Contrast enhancement
9. Geometric corrections
10. Radiometric corrections
11. Spatial image filtering
III. Polygenic image processing
12. Polygenic image visualisation - coloured composites
13. Arithmetic indices and operators
14. Polygenic transformations
15. Image classification
IV. Examples of applications (informational part of the course)
16. Nature of oceanographical satellite information
17. Classification of the shallow water seabed
18. Bathymetry
19. Ocean colour (OC)
20. Sea surface and lake surface water temperature (SSWT and LSWT)
21. Sea surface height (SSH)
22. Radar imaging (state of the sea surface)
23. Front detection
24. Analysis of temporal series and teleconnections |
| | Advanced satellite oceanography |
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| This practical course consists in brief theoretical introductions, followed by practical exercises on various techniques related to the observation of oceans, mainly using satellite imaging sensors with low spatial resolution and high radiometric resolution that detect visible light, reflective infrared and thermal infrared (AVHRR and MODIS).
The techniques studied deal with the extraction of biogeophysical parameters from the upper layer of the water column, based on the multi-spectral information recorded by these sensors. The biogeophysical parameters studied are ocean colour - related to the concentration of suspended chlorophyll-a, CDOM and mineral particles - and on the lake surface water temperature (LSWT) and sea surface temperature (SST).
We place emphasis on the qualification of input data as well as on its meaning, on its oceanological or limnological relevance, and on calculation protocols for bio-geo-physical parameters.
The first topic studied is ocean colour (MODIS): we illustrate the processes used to create level 2 and 3 products from level 0/1, raw luminance data. Several concepts of physics and geomatics are applied (geometric correction, radiometric calibration, reflectance, correction of the effects of aerosols, tests on the water's surface state, cloud detection tests, water turbidity, empirical models used to calculate the concentration of chlorophyll-a, validation of the results, etc.).
The second topic is the calculation and analysis of the SST (MODIS). We illustrate a process of calculation involving the adjustment of an empirical model that establishes a relationship between the brightness temperature recorded by the MODIS sensor in various thermal channels and the surface temperature provided by ARC-LAKE data, produced by the spatio-temporal aggregation of aligned systematic measures by an Along Track Scanning Radiometer (ATSR) sensor. This procedure is a multi-source and (image) data fusion analysis technique allowing spatial resolution refinement.
The third topic is the analysis of a time series of level 3 surface temperature raster files. These time series are constituted by Pathfinder data. Thoses are produced by aggregating measures made by AVHRR sensors embarked on the NOAA's various POES satellites. The first operation consists in product selection, product and documentation downloading, product qualification and organisation and management of data. This operation is followed by the creation of the time series, the computation of the T-T inertial matrix, its summarisation (amtrix diagonalization) by extracting the principal components in T-mode and the oceanographical interpretation of saturation temporal profiles and factorial score images, the regionalisation through a clustering process, the extraction of spatially generalised time series by region and their oceanological interpretation. |
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Learning outcomes of the course :
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| | Introduction to satellite oceanography |
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| * Understand the data acquisition process and the nature of the information recorded by imaging sensors used to observe lakes, seas and oceans.
* Know the main types of processing used for these images
* Understand why images are processed for oceanological purposes and interpret the meaning of the processes used
* Master the features of specific software tools allowing to apply these processes
* Given the diversity of the students attending this course, the requirements in terms of theoretical knowledge are not as high as could be expected from an expert who designs original solutions, and emphasis is rather placed on practical aspects. Still, students should follow basic scientific standards (rigoyr and reliability) and our expectations will obviously be tailored to each student's background. |
| | Advanced satellite oceanography |
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| * Understand the nature and the oceanological meaning of the data recorded by sensors studied in the course, as well as the various levels of processing used.
* Follow standard processing protocols and understand their limits and how they work.
* Understand the relevance of the processes' results and interpret their oceanological meaning.
* Learn how to use the features of software application that perform these processes. |
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Prerequisites and co-requisites/ Recommended optional programme components :
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| | Introduction to satellite oceanography |
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| The course builds upon basic skills in mathematics, statistics, spatial analysis, mathematical and numerical cartography, and physics. Students should also have an interest in computer science and programming.
Students will also be helped by the mindset they have acquired through various scientific courses (mathematics, statistics, physics, spatial analysis, etc.) and technical courses (numerical methods, programming, cartography, etc.) of former academic programmes or even secondary education.
Nevertheless, the variety of backgrounds among the students who generally enrol in this course will certainly require that the teaching be adapted and that many refreshers be provided in these fields. In addition, students are given the opportunity at the beginning of each class to ask questions about the content from the previous class. It is therefore up to students to act professionally and go through their notes every week in order to identify potential points of confusion. |
| | Advanced satellite oceanography |
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| The course builds upon the skills acquired during the introductory course on satellite oceanography. All the prerequisites of this introductory course are of course required for the advanced course. Students must also have an interest in using digital tools, as well as basic training and practical experience in programming. However, due to the variety of scientific backgrounds among the students who enrol in this class, the teaching will be adapted to the students' needs.
Students will also be helped by the mindset they have acquired through various scientific courses (mathematics, statistics, physics, spatial analysis, etc.) and technical courses (numerical methods, programming, cartography, etc.) of their former academic programmes or even secondary education.
The oceanographical interpretation of the results of the methods used in class will rely on knowledge of lake, sea and ocean hydrodynamics, physical oceanography, and climatology... If necessary, students will search through the scientific literature in order to carry out this interpretation. |
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Planned learning activities and teaching methods :
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| | Introduction to satellite oceanography |
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| The theoretical part of the course is given as lectures. We also offer students an exercise book, featuring numerical examples illustrating the various methods studied during the lectures. Their goal is to help students understand the theoretical concepts that we have identified over the years as being the most difficult. Examples of solutions are provided. The exercises can be done using the calculation or programming tools that are known to the students (Excel, programming languages learned in IT class, scientific calculators, etc.).
The practical part of the course consists in assignments that are mostly completed using Idrisi. It illustrates almost all the methods presented during the theoretical part of the course. Classes alternate between practical work and theoretical lectures. Students are also given standard exercises and datasets similar to those used in the practical assignments, along with the solutions, so that they can autonomously assess their ability to use the software before the exam.
Students are free to use the university's Idrisi license as well as other software applications through the ULg's VPN. For information on how to access these applications, students can visit the following web page: http://www.gitan.ulg.ac.be/cms, which also features the timetable of the computer room (B5a/4/18). Students can also use other rooms (B5a/2/35), and may contact the Geomatics unit if they wish to practise or advance in their practical assignments. |
| | Advanced satellite oceanography |
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| The theoretical introduction of each topic will consist in a lecture before each exercise. The theoretical concepts and the technical protocol will be explained.
The practical assignment will be done using various software tools (SeaDAS, Idrisi, MATLAB and/or Python). They will be organised as projects, and supervised at all times by the teaching staff in order for students to self-assess their skills by closely interacting with teachers. These practical assignments will also attempt to foster the students' curiosity and ability to come up with original solutions.
Students are also free to use the university's Idrisi license as well as other software applications through the ULg's VPN. For information on how to access these applications, students can visit the following web page: http://www.gitan.ulg.ac.be/cms, which also features the timetable of the computer room (B5a/4/18 and B5a/2/35). Students may contact the Geomatics unit if they wish to practise or advance in their practical assignments. In addition, they may use other open software resources available online (SeaDAS, R, QGIS, Octave, Python...) to independently develop the specific skills required for this study programme. Whenever possible, we encourage students to install these resources on their personal computers. |
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Mode of delivery (face-to-face ; distance-learning) :
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| | Introduction to satellite oceanography |
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| The course consists mostly in face-to-face classes, but students can install open software on their laptops and use the ULg's licenses in order to progress as their own rhythm outside of class and the academic environment. Attendance is mandatory. Classes are held in room B5a/4/18 or B5a/2/35. |
| | Advanced satellite oceanography |
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| The teaching activities are mostly face-to-face, but students can install open software on their laptops and use licenses available from the ULg, thereby learning at their own pace outside class. Attendance is mandatory. Classes are held in rooms B5a/4/18 or B5a/2/35. |
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Recommended or required readings :
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| | Advanced satellite oceanography |
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| Students are, of course, encouraged to gather scientific and technical documentation in addition to the material provided in class (online literature, software help resources, online forums, reference books, etc.). |
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Assessment methods and criteria :
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| | Introduction to satellite oceanography |
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| An ongoing non-certifying self-evaluation is carried out during demonstrations and exercise sessions, through close interaction between students and teachers. In addition, students have a book featuring numerical exercises with solutions on the one hand, in order to assess their own theoretical knowledge, and exam-type questions with solutions on the other hand, in order to test their skill in using the Idrisi software application to solve a problem that is new but similar to those seen during practical classes.
The certifying evaluation will consist in an oral exam on the course's theoretical content and a problem to solve, similar to those given during practical classes. Each part of the evaluation is worth 50% of the final mark.
This standard evaluation procedure may however be modified in agreement with the students, who will be notified of any change.
The assessment criteria are as follows: Clarity, coherence, logic, rigorousness, precision, completeness, brevity, relevance, cross-cutting nature (within the course and between courses), quality of mathematical (mathematical meaning of the different coefficients of the equation, e.g.), physics (dimensions and units, order of magnitude - scaling, e.g.) and geographical (mono and multivariate spatial and temporal interaction and meaning - type - of the variables e.g.) interpretations. Furthermore, answers will also be evaluated based on the quality and the originality of the graphic illustration since graphic expression is the scientist's specificity. It further allows demonstrating a good understanding of the phenomenon. Finally, enriching an answer with a rich personal scientific culture will also be considered a factor of excellence in the assessment. |
| | Advanced satellite oceanography |
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| A non-certifying evaluation is carried out throughout practical classes, as a close interaction between students and teachers.
The certifying evaluation will consist in a personal presentation using digital slides, during the January exam session. It will deal with the three topics studied in class, and the teaching staff will ask questions about the presentation.
This standard evaluation procedure may however be modified in agreement with the students, who will be notified of any change.
The assessment criteria are as follows: Clarity, coherence, logic, meticulousness, precision, completeness, brevity, relevance, cross-cutting nature (within the course and between courses), quality of mathematical (mathematical meaning of the different coefficients of the equation, e.g.), physics (dimensions and units, order of magnitude - scaling, e.g.) and geographical (mono and multivariate spatial and temporal interaction and meaning - type - of the variables e.g.) interpretations. Furthermore, answers will also be evaluated based on the quality and the originality of the graphic illustration since graphic expression is the scientist's specificity. It further allows demonstrating a good understanding of the phenomenon. Finally, enriching an answer with a rich personal scientific culture will also be considered a factor of excellence in the assessment. |
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Work placement(s) :
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| | Introduction to satellite oceanography |
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| | Advanced satellite oceanography |
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Organizational remarks :
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| | Introduction to satellite oceanography |
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| Classes are held on Monday morning during the first term. Theoretical lectures alternate with supervised practical work classes. Attendance to the practical classes is mandatory. |
| | Advanced satellite oceanography |
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| Ideally, classes should begin after the introductory course; however, practical considerations related to the MER master mean classes must be held during the first term. This will not be a problem for students in the second year of the master in oceanography, but for students in the MER master this course will have to be held at the end of the term, so that enough progress will have been made in the introductory course. The scheduling, which is unfortunately not ideal, will be determined based on the timetables of students in the second year of the master in oceanography and the MER master, as well as on the availability of computer-equipped classrooms and the teaching staff. |
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Contacts :
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| Items online : |
Introduction to satellite oceanography
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| Course notes |
| Course materials can be downloaded on the ULg's eCampus platform. |
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Advanced satellite oceanography
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| Course notes |
| Course materials can be downloaded on the ULg's eCampus platform. |
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