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

BER Research Highlights

ARM Evaluates Clouds in Climate Models
Published: March 20, 2002
Posted: April 01, 2002

ARM data demonstrate that a new way to model clouds is needed and possible. The representation of cloud cover in numerical models has long been recognized as the key source of uncertainty in climate predictions of radiation transfer and cloud microphysics. One important contributor to this uncertainty is that clouds are often scattered over the sky rather than in uniform layers. Furthermore, scattered clouds are often at different heights and overlap. This makes it very difficult to model the clouds and how they may change as the climate changes. Atmospheric general circulation models divide the atmosphere into vertical columns (grid boxes), and each grid box has multiple vertical layers. Certain reasonable assumptions regarding cloud layer overlap have been applied in models up to now; however, these assumptions have previously not been systematically evaluated with a comprehensive data set. The long-term data collected by continuously operating instruments deployed at the Atmospheric Radiation Measurement (ARM) sites in the Tropics, middle latitudes and the Arctic now provide sufficient statistics of clouds to make this evaluation possible. ARM investigators, Drs. Gerald Mace and Sally Benson-Troth, have completed an analysis of cloud layer overlap characteristics. Their findings show that assumptions dealing with specific cloud conditions are not supported by observations. Therefore, to avoid significant biases in simulated cloud cover, the overlap properties of these layers in models will need to be modeled. The analysis also shows that the cloud layer overlap characteristics in the middle latitudes do appear to be a strong function of season, suggesting that an overlap model based on cloud system type may be possible.

Contact: Wanda R. Ferrell, SC-74, 3-0043
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
      (formerly SC-74 Environmental Sciences Division, OBER)


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)