Sunday, 9 January 2011

The measurements

During the last week the measurements with the TEOM instrument started up. This instrument measures the aerosol mass concentration. It can be combined with special inlets which allow only specific aerosol sizes to enter the instrument. We are interested only in the smallest particles, below 10 micrometer or smaller and one of the images shows such an inlet. The TEOM measures the mass concentration with the help of an oscillating microbalance on which a special filter is mounted. The mass which is deposited on this special filter is measured via the changes in frequency of the oscillation of this microbalance. This kind of instrument is commonly used to measure the particulate mass concentration of fine dust in Europe or North America. Here, in the Antarctic we are not expecting high levels of the mass concentration. It is the aim to monitor this concentration over a long period in order to be able to detect if there is a change or trend in the concentration or not. If there is any trend, this would, e.g., indicate a change in the long-range aerosol transport or global circulation patterns. The image with the graph gives preliminary results of the first measurements of the aerosol mass concentration at Utsteinen.

In the coming week I hopefully will install the Brewer ozone spectrophotometer on the roof of the main station. The image shows me in front of this instrument. It will measure the total amount of ozone in the atmospheric column above us. For final installation it needs a very robust fixation to the rooftop. To monitor the ozone column amount in Antarctica is important because above Antarctica the ozone hole is still very large every year and the more spatially distributed precisemeasurements there are, the better a recovery of the ozone layer (what is expected to begin in the coming years) can be detected.

Besides our atmospheric composition measurements there is also research done on the biodiversity of life around Utsteinen, in particular species like cyanobacteria and lichens. This season, Zorigto Namsaraev from the University of Liege joined the expedition team (see also his blog He found already very interesting samples and it is possible to watch them under special microscopes. This brought us to the idea to put, just for curiosity, a used filter sample of the aethalometer under such a microscope. Soot or Black Carbon particles (what the aethalometer is for) are normally of the size of a few nanometer, maybe up to 200nm. Normally, for making nice images of these particles, special high tech microscopes are used, not microscopes for microorganisms of micrometer size. However, the image posted here shows besides the interesting aethalometer filter matrix a few dark spots, and these are very probable soot or black carbon particles, agglomerated together. Of course, I took a dark filter sample from the few days when the aethalometer sampled air enriched with exhaust particles from the tractors, skidoos or generators. Normally, the used sample spots are quite white and it would be very difficult to find traces of black carbon particles.

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