15 May 2017

Developing Simplified Tools to Understand the Relationship Between Convection and Large-Scale Circulation

Researchers developed a new modeling framework that separates convection’s impacts on tropical weather variability from that of the mean climate.


Accurately modeling convection and usefully understanding its relationship to climate are long-standing challenges for atmospheric scientists. A research team led by scientists at the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) developed a new approach to ease this dilemma by coupling a realistic approximation of convection’s function to a simplified global atmospheric model.


This simplified modeling framework provides a valuable new research tool, allowing complex interactions between weather and climate to be usefully broken down and attributed. The model also holds promise for exploring how convection couples to large-scale flow.


Representing the effects of moist processes in atmospheric columns (convection and cloud effects) remains a major challenge for low-resolution atmospheric models. Motivated by the shortcoming of traditional convective representations in global models, scientists developed a new approach to understand, improve, and calibrate the relationship between column physics processes and large-scale dynamics. This new intermediate modeling framework includes realistic global fluid dynamics with water vapor advection (transport). The large-scale dynamics are then coupled to convection via linear response functions. This innovative coupling approach allows moist physical processes to be meaningfully characterized and decomposed without unduly altering the basic state. The model is suitable for documenting the tropical weather impacts of widely variable (capable of being manipulated) convective tendencies, within climatological flows that can be controlled separately, albeit imperfectly. This new approach holds promise for better understanding convection and large-scale interactions.

Brian Mapes
University of Miami
Kelly, P., Mapes, B., Hu, I., Song, S. & et al. "Tangent linear superparameterization of convection in a 10-layer global atmosphere with calibrated climatology." Journal of Advances in Modeling Earth Systems 9, (2017). [10.1002/2016MS000871].