Wednesday, 26 October 2011

Next austral summer season about to begin

The next Belgian Antarctic expedition is about to begin. The first team will leave Cape Town mid November 2011. This season, I will be again part of the expedition team, however, this time towards the end of the season, from end of January to 21 February 2012. Nevertheless, there are many things to prepare right now.
Unfortunately, the power supply system of the station broke down beginning of Antarctic winter. This means that the first team arriving at the station will have to take care of a lot of extra things, and also to take care of the two Belatmos aerosol instruments – the aethalometer and the TEOM-FDMS – which are installed in the southern scientific shelter. It will have to be checked if they are in order and not damaged after the power failure and the long winter-over, and before a re-start they have to be warmed up slowly.
Engineers of the team will also take care to re-install the AERONET Sun photometer and the Brewer ozone spectrophotometer on the station roof. As they need sun for their measurements, they cannot measure during the dark winter months and only with arrival of the first expedition team, they can be re-installed. In addition, the Sun photometer has to be calibrated in Europe annually and travels therefore each season back and forth.

When I will be at the station, I will bring with me 4 new instruments, measuring UV-A, UV-B and total solar irradiation, aerosol total number concentration, particle number concentration in several size classes, and spectral scattering of the aerosol particles. I will give here a brief description of these instruments:
The Ultrafine Condensation Particle Counter (U-CPC) measures the ambient aerosol number concentration from 3nm to 3 micrometers diameter. It will be installed in the same container as the aethalometer and the TEOM-FDMS.
The Laser Aerosol Spectrometer (LAS) measures the aerosol size distribution in the diameter size range from 90nm to 7.5 micrometers (size classes can be adjusted). It will be installed in the container with the other aerosol instruments. A year-round operation is envisaged. The difference of the number concentration of the U-CPC and the integrated number size distribution of the LAS (90nm to 3 micrometer) will give an estimate of the nucleation and Aitken mode aerosol concentration (particles smaller than 90nm).
The 3-wavelengths nephelometer will measure the total scatter and the backscatter at 450, 525 and 635 nm. As the nephelometer will be installed in the same container like the aethalometer, they will probe the same air mass and therefore, a direct measure of the single scattering albedo will exist (ssa = scatter / (scatter + absorbtion) ). The single scattering albedo is an important parameter used in radiative transfer algorithms in satellite retrieval algorithms or in climate models
The irradiation sensors will be an UV-A radiometer (315-400nm), an UV-B radiometer (280-315nm) and a pyranometer for total solar irradiation (305-2800nm). The sensors will be installed on the roof of the station and year-round operation is envisaged.
In summary this means a lot of work, but all the instruments together will provide very nice data sets describing comprehensively the aerosol composition, UV radiation and total ozone at Princess Elisabeth station.

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