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Climate Variability Working Group: 21st Century CCSM3 Large Ensemble Project

Data for the Large Ensemble Experiment is accessible through the Earth System Grid website. The forty members are individually listed on the Earth System Grid and are referred to as CCSM run b30.075-01 through CCSM run b30.075-40. You must register with the Earth System Grid to download the data if you have not previously done so.

If you are interested in analyzing these runs, we kindly ask that you provide a short description of your proposed research focus and your contact information and send it to Adam Phillips (asphilli at so that other users can see what projects are underway. Please notify Adam Phillips if any publications result from your work so that they can be posted here.

Relevant Publications

  • Teng, H., G. Branstator, and G.A. Meehl, 2011: Predictability of the Atlantic Overturning Circulation and associated surface patterns in two CCSM3 climate change ensemble experiments. J. Climate, in press. [Article (.pdf)]

  • Polvani, L. M., M. Previdi, and C. Deser, 2011: Large cancellation, due to ozone recovery, of future Southern Hemisphere atmospheric circulation trends. Geophys. Res. Lett., in press. [Article (.pdf)]

  • Deser, C., A. S. Phillips, V. Bourdette, and H. Teng, 2011: Uncertainty in climate change projections: The role of internal variability. Climate Dyn., DOI 10.1007/s00382-010-0977-x. [Article (.pdf)]

  • Meehl, G. A., A. Hu, and C. Tebaldi, 2010: Decadal Prediction in the Pacific Region. J. Climate, 23, pp. 2959-2973, DOI: 10.1175/2010JCLI3296.1. [Article (.pdf)]

  • Teng, H. and G. Branstator, 2010: Initial value predictability in prominent modes of north Pacific subsurface temperature in a coupled GCM. Climate Dyn., 36, pp. 1813-1834. [Article (.pdf)]

  • Branstator, G. and H. Teng, 2010: Two limits of initial-value decadal predictability in a CGCM. J. Climate, 23, pp. 6292-6311. [Article (.pdf)]

Ongoing Project Descriptions

Arctic Sea Ice and Atmospheric Circulation Clara Deser (cdeser at, Marika Holland (mholland at, and Masha Tsikernik (masha at

We are interested in analyzing Arctic sea ice variability and the role of the overlying atmospheric circulation in the Large Ensemble. In particular, we wish to address whether the rate of Arctic sea ice loss in the various ensemble members depends on the trend in the NAO.
Atlantic Meridional Overturning Circulation Gokhan Danabasoglu (gokhan at, Joe Tribbia (tribbia at, Jim Hurrell (jhurrell at, and Adam Phillips (asphilli at

We will be studying the mechanism(s), predictability, and climate impacts of the simulated decadal variability in the Atlantic basin as depicted in the Atlantic Meridional Overturning Circulation.
The Role of Forced and Natural Variability in Future Arctic Sea Ice Loss Marika Holland (mholland at, Cecilia Bitz (bitz at, Bruno Tremblay (bruno.tremblay at, David Bailey (dbailey at, and Eric DeWeaver (deweaver at

We are interested in analyzing the role of forced versus natural variability in future abrupt Arctic summer sea ice loss. Additionally, we are interested in how natural variations in Arctic sea ice are modified with a thinning sea ice cover.
Emerging Signal at Various Spatial Scales Julie Arblaster (jma at, David Karoly (dkaroly at, Jerry Meehl (meehl at

Of interest in this study is the statistical point at which the forced signal exceeds the noise due to the internal variability of the system. We will analyse the effect that ensemble size and the use of various measures of internal variability have on the determination of a significant change, at the global, regional and gridpoint level.
The Importance of Increasing Wind Stress on the Southern Ocean Surface in Altering Mid-Depth Ocean Heat Uptake Clark Kirkman IV (ckirkman at, Cecilia Bitz (bitz at

We are interested in determining the importance of increasing wind stress on the surface Southern Ocean (from GHG and ozone changes) in altering mid-depth ocean heat uptake. Since possible mechanisms include interactions with sea ice, we would like to understand the variability of any such effect. Thus, we plan to conduct a small ensemble of sensitivity experiments with imposed Southern Ocean wind anomalies branching from the b30.075 ensemble.
Pacific Decadal Oscillation Haiyan Teng (hteng at and Grant Branstator (branst at

We'll be studying the mechanism(s), predictability and climate impacts of the Pacific decadal oscillation in the large ensemble.
Determining what Mechanisms drive Southwestern U.S. Drought Celine Bonfils (bonfils2 at, Tom Phillips (phillips14 at, and Peter Caldwell (caldwell19 at

We are interested in mechanisms that may intensify future Southwest U.S. mega-droughts. In particular, we will study the role the variability in drought-conducive SSTs and test the role of new subsurface parameterizations.