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Home > Teams > LAsers, Molecules and Environment > Themes > Analysis of gas traces

Femtosecond laser measures trace of atmospheric radicals on the Antarctica continent

published on , updated on

 

Samir KASSI
Guillaume MÉJEAN
Daniele ROMANINI
Irène VENTRILLARD

 

In collaboration with the IGE trace measurements of atmospheric radicals are performed at Dumont d’Urville, an island of the coast of Adélie land, during the austral summer.

 The Dumont d'Urville Station in Antarctica
The Dumont d’Urville Station in Antarctica
 The Dumont d'Urville Station during the austral summer
The Dumont d’Urville Station during the austral summer

 

 

 

 

 

 

 

 

 

Even though these molecules are present at very low concentrations (down to one molecule over 1012 air molecules), they have a strong impact on the atmospheric chemistry due to their high reactivity. In the frame of the CESOA, we are interested in measuring BrO and IO, which species intervene in the sulfur cycle by oxidating dimethyl sulphide (DMS) emitted by marine phytoplankton. In order to respond to atmospheric chemists, we have developed a unique instrument around a femtosecond laser (Chameleon ultra II de la compagnie COHERENT) permitting measurement of these 2 free radicals (BrO and IO), but also other relevant species such as the nitrogen dioxide (NO2) and formaldehyde (H2CO).


Transportable setup for IO and BrO analysis deployed in Roscoff

After two years of building, testing, and optimizing the instrument in the laboratory, it was finally transported to Antarctica at the end of 2011 where the measurements of those two radicals were performed for the first time.


Transportable setup for IO and BrO analysis deployed at Dumont D’Urville (January-February 2012)

After two years of building, testing, and optimizing the instrument in the laboratory, it was finally transported to Antarctica at the end of 2011 where the measurements of those two radicals were performed for the first time. Here, a preview of a portion of data for IO and the NO2 acquired by our ML-CEAS instrument are reported. No emissions of IO are observed during the storm, where there is a presence of strong katabatic wind (*) from the continent, and during the snowing period, while they are visible in between. For the NO2, a strong depence to the wind direction was also observed, with strong peaks when the air mass was coming from the station.
(*) A katabatic wind, from Greek katabatikos which means going down the slope, is a gravitational wind produced by the weight of a cold air mass tumbling down a geographical relief.


Concentration of IO and NO2 at Dumont D’Urville

- To know more about the ML-CEAS.
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