Wanli Wu, Ph.D. - US grants

This project will build a comprehensive model to simulate interactions between energy, water, and carbon dioxide using data collected from tundra regions in northern Alaska. The model will be used to examine the role of global climate change on terrestrial ecosystems in an area that is predicted to be the first to feel the greatest effects of global warming. The project will utilize satellite images and data, data collected from recent field programs, and output from other models of the individual environmental components. The project will develop a regional simulation of climate impacts on terrestrial ecosystems and address the questions of energy and water balance in the Arctic system. The research will identify critical gaps in the understanding of climate-sensitive variables in the Arctic terrestrial ecosystem as well as the exchange of carbon dioxide with the atmosphere. Therefore, the project will be an important contribution to understanding the biocomplexity of the environment in an area undergoing rapid climate change at present.

The primary goal of this proposed study is to explore the progressive integration of the impacts and processes of the arctic freshwater cycle on the local, pan-Arctic and global scales. This study will focus on analyses of the physical processes, as represented by global scale models, in the arctic water cycle. This will involve the study of processes that modify arctic freshwater budgets in the terrestrial, atmospheric and oceanic environments, the integration of these processes to produce the exchange of freshwater between the Arctic and North Atlantic, and ultimately the influence of these processes on the thermohaline circulation (THC) and global climate. The following research questions provide a framework for investigations: (1) How will changes in land cover, the amount and seasonality of precipitation and temperature influence river discharge to the Arctic Ocean? (2) How will changes in the summer Arctic frontal zone influence the location and intensity of storm tracks and, as a consequence, the mean sea level circulation over the central Arctic Ocean? (3) How do changes in river runoff, precipitation, temperature and the atmospheric circulation influence the Arctic-North Atlantic oceanic and sea ice freshwater exchange, and how do these quantities impact the global thermohaline circulation? What are the directions and magnitudes of feedbacks associated with these processes? Alterations in the freshwater input to, and the atmospheric circulation over, the Arctic Ocean influence the sea ice and ocean transports, water mass structure, the oceanic heat flux to the sea ice, and the ice mass budgets. Such interactions are likely to be important in forcing changes in freshwater exports from the Arctic and, consequently in North Atlantic deep water formation. These changes have the potential to impact global climate through the THC, which in turn can produce or damp further changes in the Arctic system. Science education has always been a principal goal of NSF. As an integral part of our study, we propose to develop a seminar course within the University of Colorado Department of Geography. The course will focus on Arctic climate processes and their role in the global system, drawing strongly from the integrated analyses studies proposed here, along with material developed under prior NSF/ARCSS studies. M. Serreze will teach the course in collaboration with the other investigators on this project and a graduate student.