Southern Ocean GasEx Blog

Dispatches from the Southern Ocean Gas Exchange Experiment

L’aventure, c’est l’aventure…

Posted by sogasex on March 29, 2008

By Bertrand Lubac, Naval Research Laboratory

[Après donc Tocqueville et BHL, me voici à mon tour parti à la rencontre des Etats-Unis. Pour ma part, les USA se limitent pour le moment au bâtiment océanographique le Ronald H. Brown, à son équipage et à la trentaine de scientifiques participant à la campagne de mesures SO GasEx. Plus précisément, le noyau dur autour duquel je gravite est l’équipe d’optique marine, appelée aussi dans le cercle des initiés l’équipe « Espuma ». Cette équipe vous a déjà était présentée par Richard Miller, et un de ces membres éminents, Christopher Buonassissi, vous a tout dernièrement fait partager son grand enthousiasme à être de la partie. Aujourd’hui c’est à mon tour de m’allonger sur le divan du blog pour vous raconter dans les grandes lignes les événements qui m’ont conduit jusqu’ici].

The point of departure has been the “Laboratoire d’Océanologie et des Géosciences” in Wimereux, a small seaside resort in the North of the France, where I met Professor Hubert Loisel. This led me to a PhD on the remote sensing of ocean color from 2004 to 2007. The principle of ocean color is to extract information on the biogeochemical and optical parameters of the ocean surface water from a radiometric signal measured by a sensor onboard a satellite. To accomplish this, two general steps are necessary to develop algorithms that relate satellite measurements to in-water information: atmospheric corrections and bio-optical inverse models. My research is mainly focused on the second step (bio-optical inverse models) and has led to a particular study that examines the influence of the marine particles on the variability of remote sensing reflectance, which defines ocean color.

This research topic has now led me to Dr Zhongping Lee. In November 2007, just after my PhD defence, Dr Lee invited me to tour his laboratory, as part of the Naval Research Laboratory (NRL) located at the Stennis Space Center. My first feeling was a mix between astonishment and wonder being faced with such human and material richness combined at NRL. This visit provided us with the opportunity to define a common research project that will be conducted during a postdoctoral fellowship at the University of Southern Mississippi (USM), also located at the Stennis Space Center.

Following this initial journey, there has been a long battle to obtain all the documents necessary to come and work in the USA. Today these administrative steps are almost finished and my postdoc at USM should start at the beginning of May. In the meantime, Zhongping Lee has given me the great chance to take part in the GasEx expedition in order to familiarize me with my new toys such the multispectral volume scattering meter (MVSM) to measure the volume scattering function of the marine particles (see picture below), and get to know the USA research and culture, and to overcome my seasickness.

As some researchers have previously confided in you, there is no marked break between work and rest on the boat. So, when the weather is not too bad and doesn’t force us to remain prostrate in our lab, days go by quickly due to a very busy daily schedule. During the GasEX III cruise, my job is to collect remote sensing reflectance spectra using a handheld spectral radiometer (see picture below), the volume scattering function of surface seawater using the MVSM, and the aerosol optical density using a sunphotometer. With these measurements we hope to improve remote sensing algorithms for primary production and optical properties of the Southern Ocean. In addition to the science, I must in my case add English courses as part of my job. One course in particular with Dr. Richard Miller is teaching me the basics to survive in Mississippi: “how’s it going “ – “Peachy”… But all this work doesn’t enable us to forget what the ship’s rules don’t allow us to have – a cool beer and a tenderness time with our girlfriends that remain at home.

After this cruise, the adventure will go on in Slidell, Louisiana and in Mississippi and I hope the adventure will always be as exciting…

[Et là-bas, on murmure « Tiens bon la rampe ! »].

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The Multispectral Volume Scattering Meter (MVSM) was developed at the Marine Hydrophysical Institute in Sevastopol, Ukraine (M. E. Lee and M. R. Lewis, 2003). The MVSM performs light scattering measurements at angles going from 0.5° to 179°, with a resolution of 0.3° at eight wavelengths (443, 490, 510, 532, 555, 565, 590, and 620 nm)

image-21.jpg

Remote sensing reflectance measurements made using a handheld spectralradiometer on the ship’s bow

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Thanks to Scott Freeman for this English version of the French book “Voyage au bout de la nuit”

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