Using the Weak Temperature Gradient Approximation to Understand Deep Tropical Convection (Invited Presentation)

Dave Raymond has made many significant theoretical, observational, and modeling contributions to understanding atmospheric convection. In addition to his direct contributions to the science, he has also greatly contributed to the career development of many young scientists, including me. When I changed research fields, Dave took me under his wing and helped kick-start my career in a way that would not have been possible without his guidance and support. I recall Dave's emphasis on causality when using models to understand deep tropical convection. In that context, he introduced me to the weak temperature gradient (WTG) approximation and taught me how to run the cloud resolving model that he wrote. I continue to use his model and WTG in my research today, and thus will focus my talk on using WTG to understand deep tropical convection.

In the deep tropics, gravity waves rapidly redistribute heating anomalies so that horizontal temperature gradients are weak. In models, this is accomplished by generating a vertical velocity that acts to counteract temperature anomalies resulting from radiative cooling and convective warming. The WTG approximation has been used to investigate cyclogenesis, characteristics of the Madden-Julian oscillation, the diurnal cycle, and large scale organization. It has also been used to tune convective parameterizations and thus improve the representation of convection in global models. In this talk, I'll discuss the WTG approximation and how it can be used in conjunction with larger-scale models and observations to better understand tropical convection.