The global hydrological cycle in a climate model hierarchy

Abstract:

Here we investigate the characteristics of the global hydrological cycle in a hierarchy of climate models. We are interested in particular in how the distribution of simulated rainfall rates (including frequency and intensity) depend on the zonal asymmetries in the climate, thermal coupling with the ocean, and feedbacks with the ocean circulation. A model hierarchy for the Community Earth System Model (CESM) is developed which includes: an aquaplanet version of the Community Atmosphere Model (CAM4/5) with prescribed sea surface temperatures, an aquaplanet CAM4/5 coupled to a slab mixed layer ocean, CAM4/5 (with continents) coupled to a slab-mixed layer ocean, and the fully coupled CESM. We hypothesize that many of the characteristics of the rainfall rate can be simulated even with the most idealized versions of the model, which would suggest a minimal set of fundamental constraints on the global hydrological cycle.