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

BER Research Highlights

Improving the Representation of Cloud Entrainment Mixing in Models
Published: October 26, 2011
Posted: February 24, 2012

Accurate representation of cloud processes is critical for understanding and simulating climate and cloud-climate feedbacks. One process that appears to play a critical role in cloud evolution, but which is not well understood or simulated in models, involves the entrainment of dry surrounding air into a cloud. It is not well known to what extent entrainment has a uniform effect on the cloud droplets (homogeneous mixing), so that all droplets evaporate at a similar rate, or whether some drops shrink much more than others (inhomogeneous mixing). The different behaviors would have a significant influence on subsequent cloud microphysics (such as a cloud’s ability to rain) and on radiative effects. Recent work examining these cloud behaviors is reported by researchers at Brookhaven National Laboratory who used the Atmospheric Radiation Measurement Climate Research Facility Southern Great Plains site during the March 2000 Cloud Intensive Observation Period. Data were analyzed from 16 non-drizzling flight legs in five warm continental stratocumulus clouds. The data indicated that inhomogeneous entrainment-mixing processes occurred more often than the homogeneous entrainment-mixing mechanism. The researchers derived a more robust characterization of entrainment-mixing processes, including a probabilistic description using a dimensionless number that indicates the degree of homogeneous versus inhomogeneous mixing. The authors argue that the common wisdom of classifying entrainment-mixing processes into several distinct types appears oversimplified. Rather, the derivation of a mechanism continuum over these types is desirable but challenging. This new study provides an important first step in that direction.

Reference: Lu, C., Y. Liu, and S. Niu. 2011. "Examination of Turbulent Entrainment-Mixing Mechanisms Using a Combined Approach," Journal of Geophysical Research: Atmospheres 116, D20207, DOI: 10.1029/2011JD015944. (Reference link)

Contact: Dorothy Koch, SC-23.1, (301) 903-0105, Ashley Williamson, SC-23.1, (301) 903-3120
Topic Areas:

  • Research Area: Earth and Environmental Systems Modeling
  • Research Area: Atmospheric System Research
  • Facility: DOE ARM User Facility

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)