- Chair, Committee of Visitors, U.S. Department of Energy's Biological and Environmental Research Programs, 2016.
- Member, AMS Awards Committee, 2016-18 and Chair for 2018.
- Reviewing Editor, Science magazine, 2014 - .
- Member, Blue Waters Science and Engineering Team Advisory Committee Member, 2014 - 15.
- Science Advisory Committee, Research Institute for Global Change (RIGC), Japan Agency for Maritime Earth Science and Technology (JAMSTEC), 2013.
- Member, Advisory Board, Korea Institute of Atmospheric Prediction Systems (KIAPS), 2012 - 15.
- Member, External Advisory Board, Byrd Polar Research Center, The Ohio State University, 2013 -.
- Member, CISL High Performance Computing Advisory Panel, 1997 - 2011.
- Chair, Fellows Committee for the Atmospheric Science Section of the American Geophysical Union, 2009-2011.
- Coordinating Lead Author (with Olivier Boucher) for Chapter 7 (Clouds and Aerosols) of the IPCC Fifth Assessment Report.
- Mentor, DISCRSS V, 2010.
- Member, Earth Day Global Advisory Committee, 2009-10.
- Founding Chief Editor, Journal of Advances in Modeling the Earth System (JAMES), 2008 - 2014.
- Member, University Review Panel for Computer Science Department, Colorado State University, 2009.
- Chair (from the U.S. side), U.S.-Japan Workshop on Global Change Research, 2008.
- Chair, Review Panel for NOAA's Climate Research and Modeling Program, 2008.
- Member, External Advisory Panel, Max Planck Institute for Meteorology, Hamburg, Germany, 2008-2016.
- Chair, External Advisory Panel, Center for Climate System Research, University of Tokyo, 2007.
- Director, Center for Multiscale Modeling of Atmospheric Processes, an NSF Science and Technology Center, 2006 - 2016.
- Member, Biological and Environmental Research Advisory Committee, U.S. Department of Energy, 2006 -.
- Co-Coordinating Lead Author (with Richard Wood) for Chapter 8
(Model Evaluation) of the IPCC Fourth Assessment Report.
- Chief Editor, J. Climate 1995 - 2004.
- Member, Advisory Board for the Earth and Sun Systems Laboratory, National
Center for Atmospheric Research, 2006-.
- Chair, Advisory Committee for the Mesoscale and Microscale
Meteorology Division, National Center for Atmospheric Research, 2003-.
- Member and former Chair, Scientific Computing Division Advisory
Panel, National Center for Atmospheric Research.
- Member, GEWEX Scientific Steering Group, 2001 -.
- Chair, GEWEX Modeling and Prediction Panel, 1997 - 2002.
- Chair, GEWEX Cloud Systems Study Science Panel, 1996 - 2000.
- Chair, Advisory Panel for Center for Clouds, Chemistry, and Climate
(C4), 1997 - 1999.
- Co-Chair, Atmospheric Model Working Group, Community Climate System
Model, 1996 - 2002.
- Member, Scientific Steering Committee for the Community Climate System
Model, 1996 -2001.
- Chair ARM Science Team Executive Committee, 1993 - 1995.
- Co-Chair, FIRE Science Team, 1983 - 2000.
- Member, Directorate Review Committee, Fundamental Science Directorate,
Pacific Northwest National Laboratories.