U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

How Cloud and Particle Characteristics Affect Atmospheric Brightness (Radiation) in the Community Atmosphere Model
Published: November 08, 2013
Posted: March 27, 2014

The Earth’s atmospheric system includes a complex and changing mix of clouds and gaseous and particulate emissions, which all interact with solar energy, or radiative fluxes, in complex ways that are difficult to predict. This complicates attempts to estimate how the Earth will warm or cool as greenhouse gases and particulates from fossil fuel combustion change. To better understand uncertainties in the current Community Atmosphere Model version 5 (CAM5), a research team led by U.S. Department of Energy scientists at Pacific Northwest National Laboratory developed and applied a sensitivity analysis framework to study the variance of the simulated radiative flux (FNET) at the top of atmosphere in the present-day climate. They found that the global mean FNET variance is dominated by the cloud forcing variance, given the assigned uncertain parameter ranges. They also found that most selected cloud microphysics- and emission-related parameters have statistically significant impacts on the global mean FNET. Three cloud microphysics parameters, associated with the fall speed of cloud ice and snow and assumed bounds on cloud droplet number, have a smaller impact than the size threshold required for ice to change to snow. Overall, these cloud microphysics-related parameters have a larger impact on high clouds than on low clouds. The team’s comprehensive approach not only estimates the contribution of each parameter to model sensitivity but also provides its statistical significance. This is an important quantification rarely obtained due to the limited sampled space of parameter uncertainty.

Reference: Zhao, C., X. Liu, Y. Qian, J. Yoon, Z. Hou, G. Lin, S. McFarlane, H. Wang, B. Yang, P.-L. Ma, H.Yan, and J. Bao. 2013. “A Sensitivity Study of Radiative Fluxes at the Top of Atmosphere to Cloud-Microphysics and Aerosol Parameters in the Community Atmosphere Model CAM5,” Atmospheric Chemistry and Physics 13, 10969-1098. DOI: 10.5194/acp-13-10969-2013. (Reference link)

Contact: Renu Joseph, SC-23.1, (301) 903-9237, Dorothy Koch, SC-23.1, (301) 903-0105
Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling

Division: SC-23.1 Climate and Environmental Sciences Division, BER


BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]

May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]

May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]

May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]

Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]

List all highlights (possible long download time)