PDRMIP: A precipitation driver and response model intercomparison project-protocol and preliminary results

In PDRMIP, 10 climate modeling groups have performed common idealized simulations to enhance our understanding of the impacts of various climate drivers on precipitation. A core set of global perturbation simulations and additional regional perturbation simulations has already been performed with initial results presented in this study and in Samset et al. (2016). PDRMIP consists of step-change experiments, but this process-based approach is highly valuable for understanding current and future precipitation changes. Precipitation changes are at the heart of two of the four questions related to the World Climate Research Programme's Grand Challenge on Clouds, Circulation and Climate Sensitivity (Bony et al. 2015) and frame many of the issues considered during the Grand Challenges on Water Availability (Trenberth and Asrar 2014) and Climate Extremes. The main PDRMIP results will be analyzed during 2016-18 to feed into the next Intergovernmental Panel on Climate Change's (IPCC) Sixth Assessment Report (AR6). The main PDRMIP results will be updated online (www.cicero.uio.no/en/PDRMIP) with information on how to obtain publicly available model output. A description of available data relevant to precipitation and the energy budget are given online. Finally, descriptions of ongoing PDRMIP analyses and activities are available online and we encourage further analyses based on the PDRMIP dataset to enhance our understanding of the diverse climate driver impacts on the energy budget and precipitation.