Orange sky asks for help

Unique device makes its dйbut in Antarctica
By Dmitry Patolichev

The main atmospheric pollutant, toxic orange-brown nitrogen dioxide gas, comprises up to 8 percent of all pollutants emitted into the air by transport and industry. However, in its strength of toxic influence and active participation in photochemical reactions it significantly outstrips all other pollutants — all put together. It may seem to be present in small concentrations but it plays a key role in forming harmful acid rain, reducing the planet’s ozone layer.

It has been a few years since the leading countries of the world organised a special network monitoring nitrogen dioxide, using fixed spectral apparatus, and continuously publishing the results. Sadly, Belarus appears as a black spot regarding such data; despite daily observations being carried out since 2010, we lack regular communication with foreign scientists, and the equipment used by Belarusian physicists does not fully meet international requirements.

The situation is soon to change, thanks to new and original spectral apparatus for monitoring nitrogen dioxide created by the National Research Centre for ozone monitoring and the Belarusian State University, with support from the Institute of Atmospheric Physics, of the Russian Academy of Sciences. The all-weather spectral module has an NO2 meter, with a multilevel input system for radiation; undergoing international calibration in Germany, at the Chemical Institute of Max Planck, it has been given a certificate of compliance with international standards and will soon return to Minsk.

“However, before the spectral module can be used to monitor the atmosphere in Belarus, it will be tested in Antarctica,” says Ilya Bruchkovsky, the device developer: a junior researcher at the National Research Centre of Ozonosphere monitoring and a post-graduate of the Physics Department of the Belarusian State University. “I’ll go there in November of this year as a member of the Belarusian expedition and I hope that it will help to clarify the picture of the distribution of nitrogen dioxide over this continent. There’s a peculiar distribution of atmospheric layers, temperature and pressure there; we expect to learn how all this affects the object of our interest. Such equipment will be used in Antarctica for the first time, and it gives our mission particular importance. Unlike LIDAR — laser radar, collecting information on the composition of the atmosphere through reflected pulses — which requires a cloudless sky, our spectral module is a passive remote sensing device, able to operate in almost any weather. It registers the spectral brightness of areas of the sky, by directing its lens and singling out specific signals. It calculates the distribution of nitrogen dioxide throughout the height of the sky with high precision, as multiple measurements are performed at different elevations of the telescope. It is most sensitive in the lower atmosphere — up to 5-6km — where most nitrogen dioxide is concentrated; at dusk, it can carry out measurements in the higher layers of the troposphere.”

Unlike its foreign counterparts, the Belarusian device has no need of a fibre optic light guide, where the signal is delivered from a receiver to a spectrograph. This is advantageous, since this method can significantly reduce ‘noise’ levels and allow measurements to be taken more quickly. In addition, as the optical fibres used by foreign devices absorb some of the ultraviolet area of the spectrum, they cannot fully determine the level of trace gases in the ultraviolet area. The BSU device has no such drawback, allowing full monitoring on the ozone layer and its levels of nitrogen dioxide.

“It’s vital to measure nitrogen dioxide in the atmosphere across various regions of the country, as this gas is short-lived, converting quickly into other chemical compounds. Some aerosol gases then attach to these, so the information we capture is mostly of local origin,” emphasises Alexander Krasovsky, a leading researcher at the National Research Centre of Ozonosphere Monitoring, and candidate of physical and mathematical sciences. “It is possible not only to measure pollution, but to take measures against the emission source, which can be easily determined by the spectral method on a loop in the atmosphere.”
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