Strategic research project of the University of Oulu
Focus institute: Kvantum
Research Unit: Sodankylä Geophysical Observatory
The chemistry and physics of the middle atmosphere are affected by solar radiation as well as energetic particle precipitation from space. We do know that energetic electron precipitation, which occurs during displays of the northern lights, will create odd nitrogen in the mesosphere, which will then proceed to destroy ozone in the mesosphere as well as the stratosphere. While solar radiation effects on atmospheric chemistry are rather well studied, particle effects are much less understood. Ozone chemistry plays a crucial role, and thus this project will establish a network of instruments for long-term monitoring mesospheric ozone.
The Mesospheric Monitoring of Ozone (MeMO) project utilises a novel, low-cost method to measure ozone in the mesosphere around 80 km altitude. Traditionally, mesospheric gases are very difficult to measure, because the respective altitudes, roughly between 50 and 100 km, can be measured in situ neither by balloons (too high), nor by satellites (too low). Valuable information has come from rocket flights, but these are expensive and of short duration and therefore unsuitable for long-term monitoring. Only remote sensing methods are feasible, and ground-based radiometers are frequently used. Radiometers can provide vertical profiles of, e.g., ozone concentrations, but they, too, are complex and cumbersome instruments.
MeMO will make use of the fact that mesospheric ozone has a radio emission in the same band as geostationary television satellites, at 11.07 GHz. Therefore standard commercial satellite receiver equipment can be used to measure ozone around 80 km altitude. This method has been pioneered by our colleagues from MIT’s Haystack Observatory, USA. The satellite dish is pointed at low elevation at the horizon such that its field of view transects the altitude of 80 km at about 600 km distance. This allows us to measure ozone above a location, which is itself inaccessible, like the Barents Sea. The project will develop the method further by improving the measurement hardware as well as by developing a completely revised retrieval algorithm based on stochastic inversion theory. The data will be compared with and validated against space-borne measurements of mesospheric chemical constituents as well as global circulation models.
MeMO is a collaboration between Sodankylä Geophysical Observatory (PI), Finnish Meteorological Institute, South-African National Space Agency, MIT Haystack Observatory, British Antarctic Survey, and the University of Otago, New Zealand.