Effect of a warming climate on multiple equilibria in a CRM using the weak temperature gradient approximation

We investigate the impact of a warming climate on multiple equilibria in limited domain weak temperature gradient (WTG) simulations. Multiple equilibria refers to the existence of a precipitating and non-precipitating steady state in identical environmental conditions. A warming climate is modeled by increasing sea surface temperatures (SST) in radiative convective equilibrium (RCE) simulations used to represent the large scale environment. The WTG approximation is based on the assumption that anomalies in the potential temperature profile are redistributed throughout the troposphere through gravity waves. In the model, convection acts to relax local perturbations in potential temperature to the reference RCE profile. By mass continuity moisture is advected horizontally from the parameterized large scale RCE moisture profile. Multiple equilibria are found to be sensitive to changes in RCE profiles for different SSTs. Changes in temperature and moisture reference profiles compete to influence the range of multiple equilibria. By individually varying the changes in potential temperature and moisture reference profiles, we find that either increasing stability or moisture in reference profiles reduces the range of multiple equilibria.