Departmental Seminar: Impacts of the North Atlantic Warming Hole on Atmospheric Circulation and Arctic Air Masses by Dr. Melissa Gervais
Dr. Melissa Gervais, Postdoctoral Fellow, Lamont-Doherty Earth Observatory,Columbia University
Title: Impacts of the North Atlantic Warming Hole on Atmospheric Circulation and Arctic Air Masses
Abstract: Increased lower-tropospheric warming in the Arctic compared to the lower latitudes, known as Arctic amplification, is an important change to the mean atmospheric circulation associated with climate change. In addition to changes in the mean state, it is important to understand the coupled earth-system mechanisms that act to perturb the distribution of Arctic and mid-latitude weather regimes in a future climate, providing insight into how we interpret future weather and climate risk.
In this seminar, I will demonstrate how the frequency of occurrence of Arctic air mass patterns may change throughout the 21st century by applying a method of self-organizing maps to the Community Earth System Model Large-Ensemble (CESM-LE) RCP 8.5 experiment to identify dominant patterns of atmospheric variability. Results from this study indicate that the development of a warming deficit in North Atlantic sea surface temperatures (SSTs) south of Greenland, known as the North Atlantic Warming Hole, may act to force changes in the frequency of some of these patterns of Northern Hemisphere variability.
To elaborate on this mechanism of future climate variability, I will provide an overview of the current knowledge of this North Atlantic warming hole and present results from my recent study demonstrating how increased freshwater fluxes are predominantly responsible for the generation of this phenomena. Finally, results from a set of Community Atmosphere Model 5 (CAM5) large ensemble (25 member) atmosphere-only modelling experiments will be presented in which surface boundary conditions in the North Atlantic Ocean are altered to explore the impacts of the North Atlantic warming hole on atmospheric circulation and patterns of Arctic air mass variability.