Organized Convection and Parameterized Versus Large-scale Physics in Global Earth System Models

Abstract

Organized convection has a profound impact on rain across the globe and contributes disproportionately to extreme events compared to other storm and convective types. It also transports tremendous amounts of heat, moisture, and momentum in the vertical, significantly impacting weather and climate. The Amazon is one of the rainiest places on earth and organized convection abounds. There are many environmental factors that help convection organize, but this work will isolate the most important ones for the Amazon and quantify their relative importance and interactions using an advanced statistical framework. Well-defined metrics of organized convection that can be readily utilized in observations and models will be identified and quantified. These will be the predictands in the statistical framework, while the predictors will be large-scale environmental variables such as temperature, humidity, and wind profiles.

This analysis will be done during the two years (2014-15) of the DOE GoAmazon2014/5 deployment using field campaign observations from the Atmospheric Radiation Measurement (ARM) user facility supplemented by satellite and reanalysis data. This framework will also be applied to a suite of runs from the Energy Exascale Earth System Model (E3SM) with varying configurations and high temporal resolution output over the Amazon. Emphasis will be on assessing the role of the convective parameterization and large-scale rain physics in producing organized convection over the Amazon in E3SM. The framework will allow us to isolate where the model is grasping the interactions between precipitation production and the large-scale environment and where it could be improved, esp. when convection becomes highly organized. The framework is expandable to other regions and global earth system models (GESMs), which could provide interesting contrasts in terms of how convection organizes in other rainy regions of the world and how other GESM convective parameterizations and large-scale rain physics interact with the large-scale environment to produce organized convection.