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

BER Research Highlights

ARM Measurements Provide Support for Conceptual Theories of Tropical Variability
Published: May 19, 2015
Posted: June 23, 2015

A large-scale weather feature known as the Madden-Julian Oscillation (MJO) is the largest contributor to variability in tropical clouds and rainfall on weekly to monthly timescales. Global climate models (GCMs) have trouble accurately simulating the initiation, strength, and evolution of the MJO, indicating that there are still gaps in conceptual theories of the MJO or their implementation in numerical models. Scientists, funded in part by the Atmospheric System Research program, used data from the Atmospheric Radiation Measurement (ARM) MJO Investigation Experiment, along with satellite data, to evaluate the sensitivity of a GCM’s MJO simulation to physical factors including entrainment, rain evaporation, downdrafts, and cold pools. This study found that differences among model versions occur primarily at intermediate values of column water vapor, where the transition from shallow to deeper convection occurs.  Simulations that have too rapid a transition from shallow to deep convection, due to weak entrainment or lack of convective organization, have poor MJO simulations.  Shallow convection is important for MJO initiation because it allows sources such as surface evaporation and large-scale transport to slowly import moist static energy into the middle levels of the atmosphere, eventually triggering the MJO propagation. Premature deep convection exports the moist static energy too quickly. These results suggest that both cloud/moisture-radiative interactions and convection-moisture sensitivity are required to produce a successful MJO simulation and strongly support the “moisture mode” conceptual theory of the MJO.

Reference: Del Genio, A. D., J. Wu, A. B. Wolf, Y. Chen, M.-S. Yao, and D. Kim. 2015. “Constraints on Cumulus Parameterization from Simulations of Observed MJO Events,” Journal of Climate, DOI: 10.1175/jcli-d-14-00832.1. (Reference link)

Contact: Sally McFarlane, SC-23.1, (301) 903-0943, 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

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)