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Historical background


Historical background and key drivers

historiqueThe ocean colour remote sensing activity of the Marine Physics and Chemistry Laboratory (LPCM, which is now part of the Villefranche Oceanography Laboratory, LOV) goes back more than 30 years ("Analysis of variations in ocean colour", Morel and Prieur, 1977, Limnol. & Oceanogr. 22, 709-722; cited more than 800 times to date). In fact, this activity began before the launch of the first ocean colour satellite. The cooperation between LOV and ACRI goes back almost 20 years.

Following their respective roles, the university and CNRS team carried out fundamental theoretical research, upstream of practical applications. The latter are within ACRI-ST's areas of expertise, as it has the computer facilities and numerical expertise that are necessary for handling huge volumes of satellite data.

It was largely ACRI ST's responsibility to contract with space agencies and coordinate the international activities for these contracts. Most of the projects were commissioned by ESA (European Space Agency). They involved, other than LPCM, foreign laboratories or organisations (e.g. GKSS in Germany, PML in the UK, JRC at Ispra). Other contracts were with CNES or the Provence and Côte d'Azur (PACA) Region and were therefore more national in their scope. A few key examples of cooperation formalised through contracts include: (Space Agency contract → ACRI ST, then ACRI subcontracts → laboratories, such as LPCM):

- Preliminary feasibility studies (1990-1995) for the MERIS (Medium Resolution Imaging Spectrometer) experiment; the ocean colour sensor MERIS was carried on ESA's ENVISAT satellite (launched in 2002).

- Creation (1995) by ESA of the ESL (Expert Support Laboratories, led by ACRI ST), responsible for defining the expected results from the MERIS "ocean colour" sensor and specifying the algorithms to be used (atmospheric corrections, "chlorophyll" algorithms and other elements).

- Preparation of the official documentation for MERIS (ATBD: Algorithm Theoretical Basis Document); preparation of the interpolation tables (atmospheric corrections, aerosol effects, bi-directionality etc.)

- As part of a contract between CNES and ACRI ST, a study on the climatology of oligotrophic ocean regions (ClimZoo) was carried out (1999-2001) to help the calibration of POLDER and future sensors on radiometrically "stable" ocean targets.

- Recurring work and periodic meetings organised by ACRI-ST on behalf of the MERIS "Quality Working Group". This involved among others, processing the calibration/validation data received on a continuous basis from "BOUSSOLE" (buoy moored since 2001 at a depth of 2400m off the coast (50 km) of Villefranche, and equipped with appropriate optical sensors).

- The design, tests on a scale model, and subsequent construction of the BOUSSOLE buoy called upon all ACRI-ST's skills in fluid mechanics and strength of materials; BOUSSOLE is the result of a joint project between CNRS-INSU, ESA, CNES, and NASA.

- A recent large-scale project (« GlobColour »), initiated by ESA and aimed at the scientific community and international institutions, involved "merging" all the data collected over a 10 year period from the 3 “ocean colour” sensors, SeaWiFS and MODIS (NASA) and MERIS (ESA). This project was led by ACRI-ST and involved LOV at various stages of control and development of the new products.

Over the last 10 years of cooperation, joint financing by ACRI ST has allowed theses to be co-supervised and occasionally, technical assistance implemented within LOV.

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