Arctic Sea Ice Loss in the Pacific Sector and Its Impacts on Sudden Stratospheric Warming Events
The Arctic sea ice is a critical indicator of climate change. The extent of sea ice coverage over the Arctic Ocean has dramatically declined over the past few decades. The impact has been extensively studied through observations suggesting a linkage between the anomalously warm Arctic surface associ...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | unknown |
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CCU Digital Commons
2022
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| Online Access: | https://digitalcommons.coastal.edu/etd/145 https://digitalcommons.coastal.edu/cgi/viewcontent.cgi?article=1197&context=etd |
| Summary: | The Arctic sea ice is a critical indicator of climate change. The extent of sea ice coverage over the Arctic Ocean has dramatically declined over the past few decades. The impact has been extensively studied through observations suggesting a linkage between the anomalously warm Arctic surface associated with the Arctic sea ice loss and the mid-latitude surface cooling in the subsequent boreal winter. This linkage could involve the wintertime stratospheric circulation by enhancing the upward planetary wave activity and weakening the polar vortex. With recent advances in climate model, more relevant studies relied on numerical simulations and some suggested that the effects of sea ice reduction on the atmospheric circulation and, in particular, on the warm Arctic-cold continent pattern at the surface are attributed to internal variability. Understanding the impact of sea ice changes on the atmospheric circulation is crucial for predicting and assessing climate changes in the coming decades as well as extreme weather. The overarching goal of this thesis is to improve our basic understanding of the physical processes that link the large-scale atmospheric circulation, particularly for Sudden Stratospheric Warming (SSW) events, and Arctic sea ice loss. In addition, the roles of internal variabilities, namely, the Quasi-biennial Oscillation (QBO) and Madden-Julian Oscillation (MJO), in modulating the atmospheric response to Arctic sea ice loss are examined. To avoid conflating the effects of sea ice loss in different sectors, this dissertation solely focuses on the Chukchi-Bering Seas (i.e., the Pacific sector) where the observed autumnal Arctic sea ice extent shows the strongest decline in recent decades. Observational data record period is too short to provide statistically convincing conclusion on how the underlying mechanism works in generating a global atmospheric response. Therefore, global climate model with well-resolved stratosphere (i.e., Whole Atmosphere Community Climate Model version 6 from the National ... |
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