Mesures in situ
Présentation
Connaissances générales sur la métrologie, les techniques et méthodes d'acquisition de données in situ en Océanographie, des systèmes de mesures, et des méthodes de traitements et d'analyse des données. Prise en main de jeu de donnée
In the past 20 years, the physical oceanographic in situ measurement technics and approaches have profoundly changed, thus revolutionized our way to do oceanography. From individual scientific cruises measurements to the emergence of autonomous platforms networks, the evolution and synergy between in situ measurements systems have significantly increased the ocean sampling capability and quality, thus our knowledge of physical Ocean. The goal of this cours is to presents the most up-to-date in situ measurements, as well as introduce the basis of physicial oceanography metrology.
In the ISMM courses, two sessions of lectures will be provided:
In Situ Measurement : The goal of this lecture is to provide a comprehensive overview on in situ measurement from sensor to data user. First the physical oceanographic sensors will be presented. Then evolution of platforms technology and applications will be developed, as well as deployments methods. Put together the in situ measurements in synergy is a challenge for regional and global observing system. The observing system networks will be presented. The international Argo networks will be take as an example to present data flow: data acquisition, processing and delivery. Eventually, application on data handling, processing and analysis methods (Optimal Interpolation) will be provided.
Metrology: The goal of this course is to acquire basics of measurements principles with essential elements to understand and standard definitions of current metrology vocabulary. Focus is made on the influence quantities and the physical basis of sensitivity and response time. Some essential detection principles of sensors are reviewed with a focus on sensors used in oceanography. That leads to describe data acquisition chains with the principles of signals sampling, filtering and analog to digital conversion. In a second part, the metrology vocabulary as described by the BIPM in the VIM (Vocabulaire International de Métrologie) is explained. That allows students to understand the differences between accuracy and precision of measurements and to understand how they can be assessed. This second part ends by the principles of measurement uncertainties calculation, as described in the GUM (Guide for Uncertainty Measurement) of the BIPM.
Pré-requis nécessaires
Les étudiants doivent posséder un bagage en mathématiques, probabilités/statistiques et des bases en informatique
Students should have a background in mathematics, probability/statistics and basic computer skills (python)
Objectifs
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Connaissances fondamentales pour une océanographe physicien sur les méthodes de mesure in situ pour une bonne connaissance des données utilisées, donc une bonne utilisation des données. |
Fundamental knowledge for a physical oceanographer on in situ measurement methods for a
good knowledge of the data used, thus a good use of the data.
General knowledge on metrology, techniques and methods of in situ data acquisition in
Oceanography, measurement systems, and methods of data processing and analysis.
Compétences visées
Connaissances fondamentales pour une océanographe physicien sur les méthodes de mesure in situ pour une bonne connaissance des données utilisées, donc une bonne utilisation des données.
To be familiar with in situ measurement technics
To have background knowledge in metrology for physical oceanographic sensors
To understand the setup, purpose and limitation of sensors, platforms, and in situ network
Ability to search, use and handle in situ data
Using dataset to contributes to a global approach (holistic approach) to problem solving
Descriptif
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- Introduction to the need, issues and problems of in situ measurements in physical oceanography
- Basics principles of measurements
◦ Influence quantities
◦ Sensitivity and response time
◦ Sensors: some detection principles
◦ Data acquisition chains
◦ Basics of analog to digital conversion
- Basics of metrology
◦ Metrology standardized vocabulary
◦ Metrology and quality
◦ Methods for calculating measurement uncertainties
◦ Different kind of systematic errors and corrections
◦ Two methods for evaluating influence quantities and standard uncertainties
◦ Probability laws with probability densities
◦ Calculation of a combined uncertainty
◦ Calculation of an expended uncertainty
- Other sensors
◦ Operation and specifications (hydrological: Oxygen; Dynamic: sound speed, current,
turbulence, waves,...)
- Observation platforms
◦ Eulerian (campaign, oceanographic, 'ship appendix', XBT, ships of opportunity, anchorages,
'gliders', marine mammals, ...)
◦ Lagrangian (surface drifters, Rafos floats, Argo,...)
- Observation networks
◦ setup of platforms into observation networks
◦ Some examples of observation networks (WOCE, Argo, MEMO, ...)
- Data processing and management
◦ Global databases (ex: Coriolis)
◦ Data quality control chain (ex: Argo)
◦ Data processing and corrections
- Data analysis
◦ Optimal interpolation method (OI)
◦ Use of OI for quality control of large datasets
- Applications
◦ ADCP data processing
◦ correction of CTD data from Glider (bias, thermal lag,...)
◦ Optimal interpolation of Argo data