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

BER Research Highlights


Relationship Between Entrainment Rate and Microphysics in Cumulus Clouds
Published: May 22, 2013
Posted: July 18, 2013

Entrainment of dry air into clouds significantly affects cloud properties. Although entrainment rate is one of the strongest controls on the climate sensitivity of climate models, the relationship between entrainment rate and cloud microphysics remains largely unexplored. To fill this knowledge gap, U.S. Department of Energy scientists at Brookhaven National Laboratory (BNL) examined the relationships between entrainment rate and key microphysical quantities in shallow cumuli collected during the Routine AAF [Atmospheric Radiation Measurement (ARM) Aerial Facility] Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign. The entrainment rate is derived from a new approach also developed at BNL. They found that an increase in entrainment rate leads to an increase in relative dispersion but decreases in liquid water content, droplet concentration, and mean droplet radius. This relationship between entrainment rate and microphysics suggests spectra broadening toward small droplet sizes and the dominance of homogeneous entrainment mixing, a possible reason why none of these cumulus clouds were drizzling. This result also sheds light on developing a parameterization that links entrainment, mixing, and cloud microphysics.

Reference: Lu, C., Y. Liu, S. Niu, and A. M. Vogelmann. 2013. “Empirical Relationship Between Entrainment Rate and Microphysics in Cumulus Clouds,” Geophysical Research Letters 40, 2333–38. DOI: 10.1002/grl.50445. (Reference link)

Contact: Dorothy Koch, SC-23.1, (301) 903-0105, Rickey Petty, SC-23.1, (301) 903-5548
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

Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]

Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]

Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]

Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]

Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]

List all highlights (possible long download time)