CIRES Council of Fellows>

Thomas N. Chase

Ph.D., Colorado State University, 1999
Associate Professor, Department of Civil, Environmental and Architectural Engineering

E-mail: tchase@cires.colorado.edu
Office: Ekeley S262
Phone: 303-492-1274
Web: Chase Research Group

Research Interests

Much of my recent work has addressed the climatic effects of landcover change both through climate model studies and observational analysis. I am particularly interested in atmospheric circulation changes which may have resulted from recent landcover changes and interactions with other natural circulation regimes such as those due to El Nino/Southern Oscillation or monsoons. Because changes in tropical circulation have been strongly related to the recently observed planetary surface warming, this research is relevant to the issues of greenhouse warming. A main issue for the future is adequately characterizing the changes in land surface properties over the course of time.

I have also been involved in examining general feedback behavior to changes in the climate system, particularly as mediated by the hydrological cycle. Because the hydrological cycle is strongly coupled to the biosphere, landcover change has many implications for hydrological cycle feedbacks and may explain some discrepancies between model simulations and observed behavior. One example of a regulation mechanism mediated by the hydrological cycle under investigation here is seen in observations of mid-tropospheric Arctic winter temperatures where a minimum is reached in late autumn which is not exceeded later in the winter despite several months of continued net energy loss. This minimum temperature can be related to convective activity over open ocean and suggesest the presence of an active regulation mechanism.

Current Research

• The regulation of Arctic mid-tropospheric temperatures through the hydrological cycle.
• Effect of landcover change on east Asian Jet.
• Comparison of vertical heating rates under increasing CO₂ in climate models and observations
• Hydrological cycle Feedbacks in simple models of the climate systm.
• Atmosphere-biosphere interactions at high latitudes in paleo-climate simulations.

Selected Publications

Tsukernik, Maria, T. N. Chase, M.C. Serreze, R.G. Barry, R. Pielke Sr., B. Herman, X. Zeng, On the regulation of minimum mid-tropospheric temperatures in the Arctic. Geophys. Res. Lett. (In Press)

Chase, T.N., R.A. Pielke Sr., B. Herman, X. Zeng, 2004. On the likelihood of a strong surface warming unaccompanied by warming in the free troposphere. Climate Research 25: 185-190.

Nordstrom, Keith M., Vijay K. Gupta, Thomas N. Chase. Salvaging the daisyworld parable under the Dynamic Area Fraction framework. Scientists on Gaia II: (In Press).

Chase, Thomas N, John A. Knaff, Roger A. Pielke Sr., Eugenia Kalnay, 2003. Changes in global monsoon circulations since 1950. Natural Hazards 29: 229-254.

Chase, T. N., B. Herman, R. A. Pielke Sr., X. Zeng, M. Leuthold, 2002. A proposed mechanism for the regulation of mid-tropospheric temperatures in the Arctic. J. Geophys. Res.- Atmospheres: 107: NO. 0, 10.1029/2001JD001425.

Chase, T.N., R.A. Pielke Sr., M. Zhao, A. J. Pitman, T.G.F. Kittel, S.R. Running, R.R. Nemani, 2002. The Relative Climatic Effects of Landcover Change and Elevated Carbon Dioxide Combined with Aerosols: A Comparison of Model Results and Observations. J. Geophys. Res. 106: 31,685-31,691.

Zhao, M., A.J. Pitman, T.N. Chase, 2001. Climatic effects of landcover change at different carbon dioxide levels. Climate Research: 17: 1-18

Zhao, M., A.J. Pitman, T.N. Chase, 2001. The impact of land cover change on the atmospheric circulation. Clim. Dyn. 17: 467-477.

Chase, Thomas N., Roger A. Pielke Sr., John A. Knaff, Timothy G.F. Kittel, Joseph L. Eastman, 2000. Comparison of Regional Trends in 1979-1997 depth-averaged tropospheric temperatures. International Journal Climatology 20: 503-518.

Chase, Thomas N., Roger A. Pielke Sr., Timothy G.F. Kittel, Ramakrishna Nemani, Steven W. Running, 2000. Simulated impacts of historical land cover changes on global climate in northern winter. Climate Dynamics 16: 93-105.

Chase, Thomas N., Roger A. Pielke, Timothy G.F. Kittel, Jill S. Baron, Thomas J. Stohlgren, 1999. Potential impacts on Colorado Rocky Mountain weather due to land Use Changes on the adjacent Great Plains. Journal of Geophysical Research 104: 16,673-16,690.

Stohlgren, Thomas J., Thomas N. Chase, Roger A. Pielke, Timothy G.F. Kittel, and Jill S. Baron. 1998. Evidence that local land use practices influence regional climate and vegetation patterns in adjacent natural areas. Global Change Biology 4: 495-504.

Chase, T.N., R.A. Pielke, T.G.F. Kittel, R. Nemani, S.R. Running.1996. The Sensitivity of a General Circulation Model to Large Scale Changes in Leaf Area Index. Journal Geophysical Research 101: 7,393-7,408.

Chase is also one of the CIRES Faculty who teach at the University of Colorado at Boulder with teaching loads equivalent to those of CU faculty rostered solely in departments and programs.