15 February 2016

Breaking Down Aerosol Complexity: A simpler representation of aerosols captures the essence of their influence on climate

Summary

DOE scientists at Pacific Northwest National Laboratory demonstrated that a minimal representation of aerosol particles is suitable for estimating aerosol effects on the Earth’s energy balance in climate models. Aerosols affect the energy balance through scattering and absorbing sunlight and through their influence on cloud droplet number concentration. Climate simulations must account for all important radiative forcing mechanisms, including those due to human-caused aerosols. But because of the variety of sizes and compositions of aerosol particles, it is computationally too expensive to represent their full complexity in multi-century climate simulations. DOE scientists met this challenge by comparing simulations using the minimal representation of the aerosol and a more complex benchmark representation, showing that the minimal representation is accurate enough for climate change simulations and sufficiently inexpensive to enable multi-century simulations. This more efficient representation is being used in the Community Earth System Model to simulate future climate change for the Intergovernmental Panel on Climate Change.

Contact
Steven J. Ghan
Pacific Northwest National Laboratory (PNNL)
Publications
Ghan, SJ, X Liu, RC Easter, R Zaveri, PJ Rasch, and J Yoon.  2012.  "Toward a Minimal Representation of Aerosols in Climate Models: Comparative Decomposition of Aerosol Direct, Semi-Direct and Indirect Radiative Forcing."  Journal of Climate 25(19): 6461-6476, doi:10.1175/JCLI-D-11-00650.1.
Acknowledgments

This work was funded by the U.S. Department of Energy, Office of Science, Scientific Discovery throughAdvanced Computing (SciDAC) Program and by the Office of Science Earth System Modeling Program. The CESM project is supported by the National Science Foundation and the Office of Science (BER) of the U.S. Department of Energy. Computing resources were provided by the Climate Simulation Laboratory at NCAR’s Computational and Information Systems Laboratory (CISL), sponsored by the National Science Foundation and other agencies. The Pacific Northwest National Laboratory is operated for DOE by Battelle Memorial Institute under Contract DE-AC06-76RLO 1830.