Regional temperature response and its variance for different climate forcers in PDRMID data

Anthropogenic aerosols have large but uncertain impacts on climate both on regional and global scales. The associated uncertainties in model estimates can be partitioned into two different sources, one arising from intrinsic uncertainties within climate models and the other arising from natural climate variability. With regards to the regional temperature effects of modern day anthropogenic aerosols, what is the related uncertainty and what part of this uncertainty stems from model differences and what from natural variability? We explore these questions by analyzing Precipitation Driver Response Model Intercomparison Project (PDRMIP) data. PDRMIP contains four different experiments in addition to the present-day base case: 1) fivefold sulfur concentrations, 2) tenfold black carbon concentrations, 3) twofold CO₂ concentrations, and 4) threefold methane concentrations. All these experiments have been performed by ten independent global climate models. We partition the temperature response to the longwave and shortwave, cloudy and clear sky components, surface terms and horizontal energy transport. This allows us to examine different processes affecting the magnitude and variance of regional temperature response of the anthropogenic aerosols. Preliminary results from this analysis will be presented. This study allows us to better understand the key processes responsible for climate model discrepancies in estimates of anthropogenic aerosol climate impacts.