An Idealized Study of Cold Air Outbreaks

Cold air outbreaks (CAOs) have large societal and environmental impacts, such as agricultural losses, infrastructure damage, changes in atmospheric circulation, etc. As the Earth experiences a climate crisis, the focus on CAOs has been diminishing, but extreme CAOs continue to occur which society is gravely underprepared for. This study looks to explore how CAOs evolve in a changing climate through idealized modeling. In addition to climate modeling, observational data is used to compare the current dynamics of CAOs to that expected in a climate change scenario. Observational data from the NCEP-NCAR Reanalysis project is used in addition to model simulations from the Community Atmospheric Model - version 5 (CAM5), of the NCAR Community Earth System Model v1 (CESM1). In the model simulations, this study prescribes sea surface temperature to a fully ocean-covered planet, an aquaplanet simulation. These differing surface temperature gradients were chosen to resemble potential global climate change scenarios and extreme climate change scenarios. The use of aquaplanet simulations creates an idealized environment conducive of understanding the mechanisms of CAOs. As the pole to equator surface temperature gradient is eliminated, echoing an extreme climate change scenario where the poles warm more than the TR, CAOs continue to be present. With these differing aquaplanet simulations this study aims to further understand the physical mechanisms of CAOs, and the role dynamics plays in their frequency and intensity.