Future Changes in Extremes in High Resolution Simulations of CESM1.3

In this study, ensembles of present day (1979-2012) and future (RCP8.5, 2070-2099) high-resolution time-slice simulations are examined for insight into climate and weather extremes. We use the CESM1.3 at 0.25° resolution in an AMIP-style configuration. The present day ensemble was forced with observed sea surface temperature (SST), and the future ensembles were forced with bias-corrected (Bacmeister et al., 2015) SST obtained from previously conducted, fully coupled RCP8.5 future simulations. This bias-corrected, time-slice approach is suitable for investigating climate and weather extremes because it removes the long-term model bias and provides improved statistics over a single, long future scenario simulation. We also conducted two ensembles of the future climate: one in which the members are created by perturbing the atmosphere and one in which each member is forced with different SST. For the latter, each boundary forcing is chosen based on the pattern of the mean SST state allowing for examination of the impact of cold/warm SST in different ocean regions on weather extremes. Some of the extremes investigated are midlatitude storms and storm tracks, tropical cyclones, and temperature (heat) extremes.