GEOPHYSICAL MONOGRAPH SERIES, VOL. 196, PP. 99-110, 2012
Investigation of Past and Future Polar Low Frequency in the North Atlantic
Polar lows are a particular kind of extreme weather event. Polar lows are subsynoptic-scale vigorous cyclones in subpolar
maritime region. They are associated with strong winds and severe weather and when developing rapidly can constitute a major
threat to human offshore activities. Here we present methods and results of our previous research to investigate long-term
frequency changes of polar low occurrences over the North Atlantic in the past and in a projected, anthropogenically warmed
future atmosphere. For the past, we downscaled reanalysis data to reproduce, detect, and count polar lows, and for the future,
we downscaled global model data from various Intergovernmental Panel on Climate Change scenarios. We found no systematic change
of polar low frequency in the past 60 years but a significant decrease of down to half as many cases for the simulated future.
We relate this decrease to an increase of vertical atmospheric stability, which is the result of more quickly rising air temperatures
compared to the sea surface. The results have recently been published in a series of articles.
Citation: Zahn, M., and