Radiative-convective-land surface equilibria: An idealized modeling approach

The concept of radiative-convective equilibrium has been a cornerstone in our understanding of the climate of the Tropical oceans for decades. Our hypothesis is that there are analagous equilibrium states over semi-arid continental regions during summer that link groundwater, plant ecosystems, geomorphology, and the atmosphere. We test this hypothesis using an idealized version of the Weather Research and Forecast model (WRF) coupled to the NOAH Land Surface Model. A control simulation of radiative-convective equilibrium over the ocean yields results that are similar to other studies and is used for comparison to two idealized land surface configurations. Both configurations represent a mixed shrubland-grassland environment, but the first is characterized by a relatively high vegetation fraction and a sandy clay loam soil, while the second configuration consists of a much lower vegetation fraction and sandy soil. In this presentation, we will describe the nature of the equilibrium states attained in the model in terms of daily rain rates, surface energy fluxes, and groundwater storage and we will show the impact of changing land surface conditions on those equilibrium states. This modeling approach may thus be a useful framework for evaluating feedbacks between ecosystems and climate change in semi-arid regions.