Michael TjernströmProfessor Emeritus of Boundary layer meteorology

I have been teaching most of the core courses in dynamic meteorology over the years, including Dynamic Meteorology, Mesoscale Meteorology and Boundary-Layer Meteorology; the two latter also at the graduate level. I have also been teaching overview courses, on Meteorology and Climate. Currently I'm also the Director for the PhD program in Atmospheric Science and Oceanography.

I often give public lectures on climate and climate change, especially in the Arctic and also communicate science in media and as a popular science lecturer.

The Arctic experiences the fastest climate change on Earth. Annually averaged near-surface temperatures are increasing 2-4 times faster in the Arctic than globally, and sea ice is disappearing rapidly with consequences for both global climate and society.

The melting of the sea ice is determined by the surface energy budget. The turbulent fluxes of heat and water vapor are important but the leading terms are the radiation fluxes, very strongly affected by clouds. Low-level clouds dominate the Arctic; summer is cloudy ~80-90% of the time and winter 50-70%. Clouds in turn also affect the vertical structure of the atmospheric boundary layer and hence the turbulent surface fluxes. Cloud free conditions leads to surface cooling and surface inversions with stable stratification, while cloudy conditions warm the surface and give rise to a shallow well-mixed structure; all is very tightly coupled! 

However, numerical weather prediction and climate models have a very hard time describing this. In my research I use field experiment data from icebreaker-based expeditions to the central Arctic Ocean. I have developed an atmospheric observatory on the Swedish research icebreaker Oden to generate more observations to directly increase understand of the Arctic atmosphere and also to inform modeling and model development.

The observatory is based on two leading ideas. First, to measure as much as practical of the vertical atmospheric column above the ship with in-situ and remote sensing instruments and, second, to do this with instruments that require minimum staff, increasing the likelihood that the observatory is actually deployed