Investigating Mid-Latitude Atmospheric Variability Due to Arctic Sea Ice Loss Using Self-Organizing Maps
Open Access
- Author:
- Staskiewicz, Samantha
- Graduate Program:
- Meteorology and Atmospheric Science (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 18, 2021
- Committee Members:
- David Stensrud, Program Head/Chair
Melissa Marie Gervais, Thesis Advisor/Co-Advisor
Chris E Forest, Committee Member
Colin M. Zarzycki, Committee Member - Keywords:
- Atmospheric Variability
Sea Ice
Arctic
Climate Change
North America
Self-Organizing Maps
SOMs
Machine Learning - Abstract:
- Arctic sea ice is declining rapidly as greenhouse gas levels and global temperatures continue to rise due to human activity. Although a robust response of the mean atmospheric circulation to sea ice loss is well established, the impact of future Arctic sea ice loss on atmospheric variability remains an open question. In this study, we analyze results from two fully coupled, “high top” Whole Atmosphere Community Climate Model (WACCM4) simulations, one with 1980-1999 seasonally varying sea ice conditions and the other with sea ice nudged to projected RCP 8.5 values over the period of 2080-2099. This model setup allows us to identify changes in atmospheric conditions directly caused by sea ice loss. To characterize atmospheric variability, we use an artificial neural network method called self organizing maps (SOMs) applied to daily DJF data over North America. The SOM method identifies the dominant patterns of atmospheric variability and how often they occur in the two simulations, allowing us to quantify the impact of sea ice loss on atmospheric circulation. Additionally, we composite days associated with each SOM node for additional variables to provide an understanding of the physical processes responsible for changes in variability between these simulations. We find the most significant responses to sea ice loss to occur in the form of modified cold air outbreaks where patterns of cold anomalies over North America become less cold but more frequent. Furthermore, we identify continental warm anomalies to become anomalously cold with sea ice loss, resulting from a contraction of the Aleutian Low which prevents warm, maritime air from reaching the continent. We also find patterns with increased Aleutian Lows to become more frequent overall with sea ice loss. This unique methodology allows us to gain better insight into how weather patterns over North America may change as a result of future Arctic sea ice loss.