Air-mass transformations into and out of the arctic are crucial components of the arctic climate system. Warm-air intrusions (WAIs) transport warm and moist air from the mid-latitudes into the arctic while cold-air outbreaks (CAOs) transport cold arctic air in the opposite direction. When CAOs occur over the ocean, a characteristic cloud field develops with cloud streets close to the ice edge and open cellular clouds further downstream. The Cold Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) was conducted in northern Norway from December 2019 to May 2020 with a focus on this CAO cloud field. In this talk, the characteristics of WAIs and CAOs during COMBLE are presented, with a focus on open cellular convection that occurred during intense CAOs. Open cellular clouds were observed in different parts of their lifecycles, with developing clouds having strong updrafts in which liquid is produced, while dissipating clouds had weaker vertical motions and were fully glaciated. COMBLE observations and WRF simulations of those clouds are compared. Additionally, the talk will present novel observations that were made of polar lows during COMBLE. Polar lows are intense and short-lived mesoscale cyclones that form during CAOs, some of which can resemble the structure of tropical cyclones on satellite images. The low pressure centers of three polar lows passed in close proximity to COMBLE and all three exhibited distinct characteristics.

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