Seasonality, latitudinal dependence and structural evolution of arctic cyclones

Arctic cyclones (ACs) are an important component of the Arctic climate system. Using the ERA5 Reanalysis and an AC track dataset with more than 18,000 tracks, we examined seasonality and latitudinal dependence and the structural evolution of ACs. The structures of ACs of different genesis regions, polar vs. midlatitude, are examined as well. Our findings show that ACs typically have an asymmetric horizontal structure with a tropospheric cold core and a lower stratospheric warm core. Cyclone asymmetry decreases, and the circulation becomes more barotropic in higher latitudes, and ACs of polar origin are more symmetric than ACs of midlatitude origin. Regarding seasonality, winter ACs are more intense, have a stronger horizontal asymmetry and a cyclonic circulation extending deeper into the stratosphere. In contrast, summer ACs have stronger warm anomalies in the lower stratosphere associated with subsidence, and the cyclonic circulation does not extend beyond 50 hPa. The latitudinal and seasonal variations of AC structure are consistent with the latitudinal and seasonal changes in environmental baroclinicity. Additionally, our analysis shows that the structural evolution of ACs is characterized by reduced vertical tilt and asymmetry, weakened temperature contrast between west and east sectors in troposphere, and reduced updraft strength.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Yang, Mingshi

Contributors dc:contributor

• Wang, Zhuo
• Rauber, Robert M
• Walsh, John E

• Arctic Cyclones
• Cyclone Structure

Statement dc:rights

• Copyright 2023 Mingshi Yang

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/120138

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F120138