The Impact of Large-Scale Circulation on Recent Rapid Climate Changes in High Northern Latitudes

• Main Author: Li, Zhe
• Other Authors: Ding, Qinghua
• Format: Thesis
• Language: English
• Published: eScholarship, University of California 2024
• Subjects: Climate change; Atmospheric sciences; Atmosphere-Ocean Interaction; Climate Dynamics; Climate Modeling; Climate-Weather Interaction; Extreme Weather; Arctic; Arctic Ocean; Greenland; Global warming; Ice Sheet; North Atlantic; Sea ice
• Online Access: https://escholarship.org/uc/item/3hv137vb; https://escholarship.org/content/qt3hv137vb/qt3hv137vb.pdf

In recent decades, global warming, predominantly driven by anthropogenic forcing and arising from an energy imbalance due to increased radiative forcing from greenhouse gases, has profoundly impacted Earth’s climate systems. This warming is most significant in high northern latitudes, manifesting in various ways, such as sea ice melt, upper ocean warming in the Arctic, the slowdown of the Atlantic Meridional Overturning Circulation (AMOC), Greenland ice sheet retreat, changes in extreme weather patterns and related moisture transport near the Arctic, etc. Previous studies have extensively focused on the role of CO2 forcing in contributing to these changes, while the influence of internal atmospheric variability - large-scale atmospheric circulation - remains less explored. In particular, these phenomenon were studied separately, which hinders us from gaining a deeper insight into the large-scale climate dynamics behind recent rapid changes in the climate system of high northern latitudes. This dissertation addresses this gap by examining how large-scale atmospheric circulation influences these changes, ranging from studying high northern latitude oceans to understanding circulation-extreme weather interactions. Although these observed rapid change appear to be disconnected, actually my analyses solidly suggest that they are physically connected by recent large-scale atmospheric circulation variability with dynamical sources in the tropics.In the following sections, consisting of three components, I focus on recent rapid changes in high northern latitudes: I. upper Arctic Ocean warming; II. subpolar North Atlantic warming hole; III. a poleward shift pattern of atmospheric rivers (ARs) in the extratropics. In the first part, I investigate the role of large-scale circulation in warming the upper Arctic Ocean over the past 40 years. Observational and modeling analyses reveal that internal atmospheric variability, characterized by a multiyear trend in summertime circulation, has significantly contributed to upper ...