A Brewer ozone spectrophotometer at Princess Elisabeth Station, East Antarctica
Since January 2011 the Royal Meteorological Institute of Belgium (RMI) has been operating Brewer #100 (a MkIII double monochromator) at the Belgian Princess Elisabeth research station in East Antarctica. The station is situated around 180 km inland from the coast, near the Sør Rondane Mountains in Dronning Maud Land, on the Utsteinen ridge (71.95°S, 23.35°E; 1400 m asl). The station is inhabited from November to the end of February and operated under remote control during the other months.
Article by Dr. Alexander Mangold, Royal Meteorological Institute of Belgium (RMI).
Brewer#100 was kindly put at RMI’s disposal by the Royal Dutch Meteorological Institute (KNMI), who previously operated the instrument. After refurbishment and adaptation to cold environments by Kipp & Zonen, the instrument left Belgium by ship in November 2010, was unloaded at the coast 7 weeks later, and finally arrived as a ‘Christmas present’ on 25 December 2010 at Princess Elisabeth Station.
For the set-up of the instrument in the Southern Hemisphere, attention has to be paid to the correct orientation of the Brewer. Contrary to the Northern Hemisphere, it should be set up with its North-sign pointing to the South and the tracker needs to take into account that the sun’s azimuth values of a day start in the South (180°), moving over the East (90°) and the North (0°/360°), to the West (270°) and finally back to the South (180°).
By mid-January 2011, Brewer#100 was operational and it has been measuring since then total ozone, spectral UV and aerosol optical depth (AOD) at the five ozone wavelengths (303.3, 310.1, 313.5, 316.8, 320.1 nm). In addition, a sun scan routine has been included in the daily schedule, which performs sun scans between 335 and 345nm to mimic standard AOD observations at 340nm (which can in turn be compared to AERONET sunphotometer observations at 340 nm).
Although the Brewer could operate through the whole year, Brewer#100 has only been operated during the summer period when the station is inhabited. During almost 9 months there is nobody at the station and the risk would be too high that the valuable instrument would encounter serious damage due to the extreme conditions during the Antarctic winter (very strong winds and temperatures down to –40 °C). However, in the future, the research station might be manned the whole year.
In order to maintain data quality, Brewer#100 was shipped back to Belgium for a service and calibration, which happened in April 2014, and was then returned to Antarctica for the next summer measurement season.
In Antarctica, the so-called ozone hole (depletion below 220 Dobson Units) has appeared each austral spring for several decades, destroying ozone almost completely at altitudes between 15 and 20 km, and reducing total ozone by a third or even more. This large reduction of total ozone increases the UV radiation at the surface.
Until now, during austral summers at Utsteinen, the average total ozone values have been around 300 to 320 DU, with the UV Index between 5 and 7. However, in December 2014, due to the horizontal displacement of a remnant of the ozone hole above Dronning Maud Land, total ozone dropped to values around 200 DU and the UV Index reached extreme values, up to 10 on 3rd December 2014.
The danger resulting from this high UV exposure to human skin and other living organisms (besides the people working at the research station, micro-organisms inhabit the rocks of the Sør Rondane Mountains) is even more tangible due to the high surface albedo of the surroundings and the high altitude (1400 m asl).
Because of the double monochromator, the MkIII Brewer is particularly suited to the spectral measurement of ultraviolet radiation with the correct response function to calculate the UV Index.
Find out more at: http://ozone.meteo.be.
Brewer 100, Princess Elizabeth, Antactica
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