Seasonality, latitudinal dependence and structural evolution of arctic cyclones

Yang, Mingshi

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

Description

Title

Seasonality, latitudinal dependence and structural evolution of arctic cyclones

Author(s)

Yang, Mingshi

Issue Date

2023-05-02

Director of Research (if dissertation) or Advisor (if thesis)

Wang, Zhuo

Committee Member(s)

• Rauber, Robert M
• Walsh, John E

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Arctic Cyclones
• Cyclone Structure

Abstract

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.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Mingshi Yang

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