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Keeping a lid on the ice cap

Raised footprints. The pressure of the footstep compresses the snow underneath it. The surrounding snow is blown by the wind, the hardened snow of the footprint remaining.
Raised footprints. The pressure of the footstep compresses the snow underneath it. The surrounding snow is blown by the wind, the hardened snow of the footprint remaining.

Presentation summary for the IPY Science Conference 2010 in Oslo by Dr Markus Frey

A science team presents their observations of concentrations of nitrogen oxides (NOx) — a gas that plays a key role in Antarctica’s atmospheric chemistry — measured for the first time at one of the highest points (Dome C) on the East Antarctic Plateau. Their findings will improve atmospheric chemistry models of the Antarctic *troposphere and, refine the interpretation of ice core records.

Nitrogen oxides influence the self-cleansing capacity of the atmosphere, for example, through control of the production of ozone — a *greenhouse gas and pollutant.

In Antarctica, levels of NOx vary across the continent with unusually high amounts at the South Pole. Previous research revealed that polar snow is a makes a significant contribution of NOx to the lower atmosphere. Sunlight drives reactive nitrogen out of the *snow pack.

Session information

Speaker:
Dr. Markus Frey

Contact:
Mobile: +44 (0)7514 951861
Email: maey@bas.ac.uk

Wednesday 9 June @ 10.00
Session: T1-3

The research team found similarities between the amounts of the gas measured at South Pole and at Dome C. They were surprised to find a strong daily cycle of nitrogen oxide production with maximum concentrations occurring not at noon but during evenings. These findings help explain the relationship between the source of the gas from the snow pack, and the mixing of the atmosphere above it.

The team report that at certain times during the day the atmosphere at the surface of Dome C acts as a “lid”, preventing emissions of NOx from being released from the snow pack. Since Dome C is assumed to be representative for large areas of the East Antarctic Plateau, these findings will be significant for two reasons: firstly they will give a better understanding of how to include the upper snow pack into atmospheric chemistry models of the Antarctic *troposphere and, secondly, the findings will contribute to the interpretation ice core records with regard to reactive nitrogen levels in the atmosphere in the past climate — so far not well understood.

Definitions

Troposphere
the lowest region of the earth’s atmosphere, closest to its surface
Greenhouse gas
an atmospheric gas that contributes to the greenhouse effect
Snow pack
an area of naturally fallen snow on the ground