AOPP Seminar - Understanding polar feedbacks in radiative-advective equilibrium

Abstract - The polar atmosphere exists in a state of radiative-advective equilibrium (RAE), where radiative cooling to space is balanced by lateral energy advection. This is a very different situation from the more familiar radiative-convective equilibrium (RCE), where radiative cooling is balanced by surface fluxes. Most of our intuition about climate sensitivity and feedbacks is based on RCE. The physics of RCE and RAE are profoundly different, however, so this intuition fails qualitatively for polar climates. This leads to difficulty in interpreting  and quantifying the relative roles of different forcing/feedback mechanisms in causing polar amplification of surface temperature change in climate model simulations. Resolving these difficulties requires more robust physical understanding of the RAE state. I will discuss this issue in the context of a single-column model of RAE with a simple but realistic description of advective heating, focusing in particular on lapse-rate changes and the constraints on dry and moist energy transports.