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Identifying and Comparing Dynamics Driving Different Types of Arctic Cyclones

Presentation Date
Friday, December 15, 2023 at 8:30am - Friday, December 15, 2023 at 12:50pm
MC - Poster Hall A-C - South



Arctic cyclones have demonstrated severe impacts for the growing human activities in the Arctic through causing wind gusts, heavy precipitation, coastal flooding, coastal erosion, ocean wave surges, and rapid sea ice retreat. Recent studies have revealed new dynamic structures and mechanisms of a number of recently observed intense, impactful Arctic summer cyclones. However, Arctic cyclones have exhibited very different intensities, origins, and propagation trajectories. To obtain a more complete picture of Arctic cyclone dynamics, we conduct modeling studies on selected three different types of Arctic cyclones: an intense cyclone occurring in Aug 2016 that exerts noted high impacts on sea ice and ocean; a weaker Arctic cyclone in Aug 2021 that unusually propagated to the southern Beaufort Sea; and a transitioned cyclone from a typhoon, named as "Merbok'', in Sep 2022, which caused extreme high ocean wave and coastal flooding events. Dynamical analysis reveals that the three cyclones share a common baroclinic feature. However, the baroclinic instability plays different roles in the three cyclones. For the 2016 cyclone, the baroclinic instability mainly occurs near the surface due to the ocean-sea ice thermal contrast and in the upper troposphere resulting from synoptic waves induced by a prior cyclone at an initial period. Then the cyclone stacks with a lower stratospheric vortex at its maturing stage and evolves into a barotropic structure. The weak cyclone in 2021 shows weak baroclinic instability throughout its lifetime. The cyclone Merbok is mainly characterized by a strong baroclinic structure of conventional midlatitude cyclones after its transition. Further potential vorticity (PV) analysis reveals that a downward intrusion of lower stratospheric Arctic vortex plays important roles in intensifying and maintaining the first two cyclones. However, there are no identifiable stratosphere-troposphere interactions in Merbok’s development. Our study here suggests a necessity of further comprehensive analysis of more cyclone cases for establishing solid Arctic cyclone dynamics.

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