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

BER Research Highlights


Timescale Matters to Aerosol Effects on Deep Convective Clouds
Published: November 01, 2013
Posted: February 04, 2014

Modeling studies have indicated a wide range of potential responses of deep convective storms to increased aerosol loading. Some studies indicate that cloud systems will be invigorated under polluted conditions due to delayed warm-rain formation, greater lofting of cloud water in convective updrafts and enhanced freezing, latent heating, and buoyancy. However, these studies modeled cloud systems using short integration periods, often only a few hours, which are not necessarily applicable to the response of deep convection over large spatiotemporal scales because they neglect feedbacks between convection and its large-scale environment. To address this problem, Department of Energy researchers conducted simulations with a cloud-system-resolving model over a 7.5-day period of active monsoon convection, using environmental conditions observed during the Atmospheric Radiation Measurement (ARM) Tropical Warm Pool-International Cloud Experiment (TWP-ICE). To test the convective invigoration effect, heating perturbations were applied to convective updrafts above the freezing level to mimic the impact of enhanced freezing and ice processes on latent heating in polluted conditions. Unlike previous studies, heating perturbations were applied in updrafts and cooling in downdrafts to give no net change in moist static energy. This allows for an unambiguous evaluation of the impact of convective-scale heating perturbations in the context of feedback and adjustment with the larger-scale environment. In the perturbed simulations, there was an initial invigoration of convective updrafts and surface precipitation, but convection returned to its unperturbed state after about 24 hours because of feedback with the larger-scale environment. In contrast to recent studies, the researchers concluded that the invigoration effect is intimately coupled with larger-scale dynamics through a two-way feedback, and, in the absence of alterations in the larger-scale circulation, there is limited invigoration beyond the convective adjustment time scale. These results have important implications for understanding the effects of aerosol changes on tropical cloud systems; however, additional studies addressing midlatitude clouds and allowing feedbacks between the convection and large-scale forcing are needed before the question of aerosol impacts on deep convection can be fully resolved.

Reference: Morrison, H., and W. W. Grabowski. 2013. “Response of Tropical Deep Convection to Localized Heating Perturbations: Implications for Aerosol-Induced Convective Invigoration,” Journal of the Atmospheric Sciences 70, 3533-55. DOI: http://dx.doi.org/10.1175/JAS-D-13-027.1. (Reference link)

Contact: Wanda Ferrell, SC-23.1, (301) 903-0043, Sally McFarlane, SC-23.1, (301) 903-0943, Ashley Williamson, SC-23.1, (301) 903-3120
Topic Areas:

  • 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)