Theory of the atmospheric general circulation: coupling to polar climate and cryospheric change.

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The complexity of climate change at high latitudes presents many challenges to researchers interested in the atmospheric general circulation. For example, the last two years included the most extreme Artic sea ice minimum and the most rapid spring-to-summer retreat of Northern Hemisphere snow cover ever recorded. These years also featured extreme midlatitude weather events which some researchers have speculated are linked to recent Arctic change. Rapid climate change at high latitudes is taking place in the context of long term anthropogenic global change, is strongly influenced by climate feedbacks, and is connected to changes in the planetary scale general circulation of the atmosphere and oceans. But key aspects of high latitude climate change are not robustly predicted by climate models, and the climate feedbacks and dynamical coupling to the planetary-scale circulation of the atmosphere and oceans remain poorly understood. The PI leads an original basic research program whose long term objective is to better understand the atmospheric circulation outside the tropics, its variability on decadal timescales, its sensitivity to climate change, and its coupling to the environment. Alongside, in the last six years, he has developed and now leads a collaborative applied research program in Arctic and cryospheric modelling, focusing on prediction of snow cover and sea ice on seasonal to decadal timescales. The PI's basic research program centres on a hierarchy of climate models that ranges from novel configurations of simplified representations of the atmosphere to state of the art Earth System Models (ESMs) that endeavour to include the physical, biological, and chemical processes controlling Earth's climate. This basic research program is needed for the PI to be able to leverage his applied work to improve climate prediction and advance our understanding of climate. The PI's research aims, over the long term, to advance the theory of the atmospheric general circulation. Its primary application is towards climate change and variability at high latitudes. This Discovery Grant proposal is intended to support the PI’s basic research program for the next six years. The research's objectives over the next six years are1) To learn how high latitude climate is linked to variability associated with atmospheric planetary waves, with a focus on a so-called "linear interference effect" that the PI's group has explored in groundbreaking research.2) To understand the two-way connections between midlatitude and polar variability using a hierarchy of climate models of varying degrees of complexity, which has been a hallmark of the PI's successful theoretical research.3) To identify mechanisms in the coupled ocean atmosphere system controlling persistence and predictability of decadal climate signals in the midlatitudes, with a suite of comprehensive ESM simulations being generated using Canadian and international computing resources.4) To carry out targeted analysis on the impact of Arctic variability on the Arctic environment in the setting of lake dynamics studies, through collaborative research. The lake work will combine meteorological analysis with multiple-decade long Arctic lake records, as well as regional model representations of present day conditions and under conditions of projected global warming.The PI maintains a group of excellent undergraduate students, graduate students, postdoctoral fellows, and research associates to support his research program; they receive rigorous training and as a result advance well professionally. Resources requested in the proposal will go mainly to support students, and are intended to continue the applicant’s track record of high level training and follow on placement.