D'Ortenzio F.,CNRS Oceanography Laboratory of Villefranche |
Lavigne H.,CNRS Oceanography Laboratory of Villefranche |
Besson F.,CNRS Oceanography Laboratory of Villefranche |
Claustre H.,CNRS Oceanography Laboratory of Villefranche |
And 14 more authors.
Geophysical Research Letters | Year: 2014
Two profiling floats, equipped with nitrate concentration sensors were deployed in the northwestern Mediterranean from summer 2012 to summer 2013. Satellite ocean color data were extracted to evaluate surface chlorophyll concentration at float locations. Time series of mixed layer depths and nitrate and chlorophyll concentrations were analyzed to characterize the interplay between the physical-chemical and biological dynamics in the area. Deep convection (mixed layer depth > 1000 m) was observed in January-February, although high-nitrate surface concentrations could be already observed in December. Chlorophyll increase is observed since December, although high values were observed only in March. The early nitrate availability in subsurface layers, which is likely due to the permanent cyclonic circulation of the area, appears to drive the bloom onset. The additional nitrate supply associated to the deep convection events, although strengthening the overall nitrate uptake, seems decoupled of the December increase of chlorophyll. Key Points Nitrate profiling floats observed deep convection and bloom in the MediterraneanCyclonic basin circulation appears critical for bloom onset ©2014. American Geophysical Union. All Rights Reserved.
Ricaud P.,CNRS Laboratory for Aerology |
Ricaud P.,Meteo - France |
Genthon C.,French National Center for Scientific Research |
Durand P.,CNRS Laboratory for Aerology |
And 10 more authors.
Boundary-Layer Meteorology | Year: 2012
The HAMSTRAD (H 2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) microwave radiometer operating at 60 GHz (oxygen line, thus temperature) and 183 GHz (water vapour line) has been permanently deployed at the Dome C station, Concordia, Antarctica [75°06′S, 123°21′E, 3,233 m above mean sea level] in January 2010 to study long-term trends in tropospheric absolute humidity and temperature. The great sensitivity of the instrument in the lowermost troposphere helped to characterize the diurnal cycle of temperature and H 2O from the austral summer (January 2010) to the winter (June 2010) seasons from heights of 10 to 200 m in the planetary boundary layer (PBL). The study has characterized the vertical resolution of the HAMSTRAD measurements: 10-20 m for temperature and 25-50 m for H 2O. A strong diurnal cycle in temperature and H 2O (although noisier) has been measured in summertime at 10 m, decreasing in amplitude with height, and phase-shifted by about 4 h above 50 m with a strong H 2O-temperature correlation (>0.8) throughout the entire PBL. In autumn, whilst the diurnal cycle in temperature and H 2O is less intense, a 12-h phase shift is observed above 30 m. In wintertime, a weak diurnal signal measured between 10 to 200 m is attributed to the methodology employed, which consists of monthly averaged data, and that combines air masses from different origins (sampling effect) and not to the imprint of the null solar irradiation. In situ sensors scanning the entire 24-h period, radiosondes launched at 2000 local solar time (LST) and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at 0200, 0800, 1400 and 2000 LST agree very well with the HAMSTRAD diurnal cycles for temperature and relatively well for absolute humidity. For temperature, HAMSTRAD tends to be consistent with all the other datasets but shows a smoother vertical profile from 10 to 100 m compared to radiosondes and in-situ data, with ECMWF profiles even smoother than HAMSTRAD profiles, and particularly obvious when moving from summer to winter. For H 2O, HAMSTRAD measures a much moister atmosphere compared to all the other datasets with a much weaker diurnal cycle at 10 m. Our study has helped characterize the time variation of the PBL at Dome C with a top around 200 m in summertime decreasing to 30 m in wintertime. In summer, from 2000 to 0600 LST a stable layer is observed, followed by a well-mixed layer the remaining time, while only a nocturnal stable layer remains in winter. In autumn, a daytime convective layer shallower than the nocturnal stable layer develops. © 2011 Springer Science+Business Media B.V.
Rabier F.,Meteo - France |
Bouchard A.,Meteo - France |
Brun E.,Meteo - France |
Doerenbecher A.,Meteo - France |
And 33 more authors.
Bulletin of the American Meteorological Society | Year: 2010
The Concordiasi project was undertaken in Antarctica to reduce uncertainties in diverse and complementary fields in Antarctica science. Some of the objectives of the project involved investigations of precipitation to constrain the mass budget over Antarctica and stratospheric ozone depletion. The project was a joint French-United States initiative that started during the International Polar Year (IPY). The project was undertaken over Antarctica during September-November, 2008, December, 2009, and was expected to continue between September-December, 2010. It was undertaken as part of the IPY-The Observing System Research and Predictability Experiment. Participants in the project included scientists from France, the US, Italy, and Australia, along with international organizations such as the European Center for Medium-Range Weather Forecasts (ECMWF).
News Article | March 21, 2016
One thousand kilometres from the Antarctic coast, a 12-strong crew is overwintering at one of the most remote places on Earth. The Concordia Station, a French-Italian research base on the Antarctic Ice Sheet, is truly in the middle of nowhere; the next nearest station is 560km away, and all the crew can see if they look around is flat whiteness. The last plane left for the winter in February, leaving the base completely isolated. It won’t see the Sun for four months and temperatures will drop to below -60 Celsius. Oh, and because it’s 3,200 metres above sea level, inhabitants have to make do with about a third less oxygen than at sea level. It’s not a normal environment for humans, which is exactly why Floris van den Berg is there. A medical doctor sponsored by the European Space Agency, Van den Berg is running a series of research projects at Concordia to explore the physical and psychological effects of living in such surroundings—and the results could give an insight into how we’ll cope with long-distance space travel. “ESA is interested in this place because it’s one of the only places that you have, like, true isolation,” Van den Berg said in an interview over Skype. We spoke after his colleagues were asleep, as he conceded that the 512kbps satellite connection at the base was “quite shitty” if multiple people tried to Skype at the same time. A family doctor from the Netherlands, Van den Berg said it was the remote location that attracted him to the unusual job posting in the first place. Having served as a doctor on expeditions around the world, deepest Antarctica seemed like an impressive location to add to the list. “Working for the European Space Agency is also quite cool in my opinion,” he added. Concordia has several rather unique parallels with space, which makes it ideal for ESA’s research. As we venture further afield—to Mars, for example—astronauts will be spending more time in close quarters and completely isolated from the rest of the world. With current technology, it takes around eight months to send a robotic mission to the Red Planet. Given its total isolation for months at a time, Concordia is sometimes nicknamed “White Mars.” Van den Berg is responsible for collecting a varied slate of samples and data to help give insight into how this environment could affect humans’ physical and psychological wellbeing. One particularly interesting study involves teaching his crewmates to drive a flight simulator of the Soyuz spacecraft, which is currently used to transport astronauts to the International Space Station. It’s a stripped-down simulator with one seat and two joysticks, which users can practice piloting and docking. Van den Berg explained that it’s installed in the Concordia laundry room because it wouldn’t fit in his lab. After initial instruction, he will split his team into two groups; one will receive training on the simulator every month and the other every three months, and he’ll monitor their performance to see how quickly their abilities fade in the environment. “The idea is, if you send people to Mars and they’re going to be in a spaceship for six to nine months they’ll probably get a bit bored, but when they arrive at Mars they have to be quite focused on how to land the Mars lander,” he explained. The 'Simskill' Soyuz simulator. Image: Institute of Space Systems, University of Stuttgart–Andreas Fink Another Antarctic base, British Halley VI, is also conducting the simulator training. As Halley is at a lower altitude, this should help distinguish the impact of the isolation factor from that of the hypoxic conditions. A control is also being run in Stuttgart, Germany. Unsurprisingly, the flight simulator is the most popular of Van den Berg’s experiments, and he admitted he sometimes does it in his free time too. Aside from the simulator, Van den Berg runs regular tests on himself and the rest of the team, which consists of technical staff and researchers working in fields such as climate and astronomy. Using a CT scanner (the first one in Antarctica, installed in the video room) he looks at people’s bone density, which is a major health issue in space travel. He also takes blood samples and analyses them using flow cytometry—which sorts the different cells in the sample—to see how the conditions affect the immune system; NASA astronauts on the ISS are also doing this, which will offer an interesting comparison. “You see a lot of changes, especially in the beginning when people arrive,” Van den Berg said. “Because of the lack of oxygen, you see stress hormones go up quite a bit, which sort of suppresses the immunological response.” Psychological factors are naturally as pressing as physiological ones when it comes to being cooped up for so long, and Van den Berg regularly asks people to fill in questionnaires about their mood and sleep habits. Participants also wear watches that track their activity (especially useful for tracking sleep, which people are often bad at accurately reporting) and interact with beacons on the base to record their movements. “I was quite surprised that everyone was OK with participating with this study, because it’s really like ‘Big Brother is watching,’” said Van den Berg. Participation in all of the research is voluntary. The current Concordia crew on their arrival. Image: ESA/IPEV/PNRA-B. Healey “What’s known from previous years is that in the winter everyone gets a little bit down, so people isolate themselves a bit more [and] spend more time in their bedroom and less in the living room,” he added. “This is something you can measure in detail, to see what the group dynamics are, who is visiting which areas, and how much time people spend alone or with each other.” This is all correlated with people’s questionnaire responses. Of course, Van den Berg is not immune to the psychological effects that he’s collecting data on, and he said that part of his attraction to the job was the “personal experiment” of living at the base. He said the biggest challenges, after adapting to the low oxygen, were coping with the isolation and also having to constantly bug his cohabitants to take part in his studies on top of their own work. There is another doctor at the research base to act as a clinician if people get sick or injured (the base is equipped for surgery as it’s impossible to get people to a hospital for a large chunk of the year, though the team is naturally as careful as possible not to need it). Van den Berg heads up the rescue team if there’s an incident outside the base—“with the cold here it’s really just what we call ‘scoop and run’: get them on a plank and get them inside,” he said. There is the occasional unexpected setback. When his CT machine arrived at the base in a shipping box, it had a hole in the side that looked suspiciously like a forklift had run into it. Without a repair service for thousands of kilometres, Van den Berg had to figure out how to fix it himself, with help over email and Skype. “Luckily there wasn’t too much structural damage and with tape and common sense I could fix it,” he said. With most of a year left to go, Van den Berg sounded enthusiastic about his mission but a little apprehensive. “I’m always ending up with these things where you think, ‘Oh it’s really nice!’ and then you end up in the middle of nowhere and you think, ‘Why did I do this?’ This is, I think, the story of my life,” he said. “But I’m happy because it’s a really interesting place to be.” So far, he hasn’t lost his travel bug, and working for ESA has given him a taste for venturing even further afield. Now 32, he said that if ESA were to put out a call for astronauts soon, he’d apply. With the White Mars experience under his belt, he has more of an idea than most about what he’d be letting himself in for. Correction: This story originally put the base's altitude at 2,300 m above sea level; it's actually 3,200 m. We've corrected the typo.