Aeronomy of hydroxyl airglow variability by means of high-resolution telescope observations and gravity wave simulations

Abstract

Are there waves on the fjord right now? “Easy to find out”, you might think. Just go down to the water and have a look. Now imagine that you are in Oppdal, about 90 kilometres away, trying to see the waves on the fjord in Trondheim. You would need a very good telescope to do that!

This is how I felt with my PhD thesis. Only that my waves are not on the water, but in the air above us. These waves start in the lower parts of the atmosphere and travel upwards. This way, they connect different parts of the atmosphere and drive the general circulation across the whole globe. Computer models for weather and climate require a good understanding of these waves. This is why I set out looking for these waves. I found them in a thin layer at an altitude of about 90 kilometres, where the northern lights shine and the atmosphere is at its coldest. In this special layer, there is a glow which shines just outside the visible range, in the infra-red light. It is called the hydroxyl airglow.

Together with the house-sized Nordic Optical Telescope (on La Palma, Spain) and four years of research at NTNU, I could measure and characterise wave smaller than 5 meters long and 90 kilometres high up above our heads, which have not been seen before. But I did not stop there. My thesis contains four papers with different research goals. Using computer models, I researched how waves, which are several kilometre long, can change the colour of the hydroxyl airglow in previously unknown ways. I was able to show how the background of astronomical observations from the telescope can be an invaluable source for atmospheric scientists. Lastly, I used these data from the telescope to measure quantum-mechanical probabilities and provide a dataset for future scientists to use.

So next time you find yourself on a mountain close to Oppdal, find your camera and zoom in towards the north, towards Trondheim. Can you see the waves on the fjord?