Tropical Influences on Greenland Surface Conditions over the Past 400 Years

Despite the contribution of the Greenland Ice Sheet (GrIS) to global sea level rise, the lack of a complete understanding of its driving mechanisms largely constrains future model projections. Recent set of climate models struggle to replicate an observed increase in both the frequency and intensity of so-called Greenland blocking events that has a potential in driving enhanced surface melt conditions, especially in summer. Here, we present results from an atmospheric wind-nudging experiment to account for the bias of climate models in simulating wind-driven processes over GrIS. Since, brief observational records limit model development efforts we further use paleoclimatic proxy data assimilated model experiments that provide new opportunities to place recent climate changes in and around the Arctic in the context of long-term high-latitude variability. Building off of previous work, we investigate the relative role of internal atmospheric variability in modulating GrIS surface conditions using the newly available Ensemble Kalman Fitting Paleo-Reanalysis (EKF400) version 2, with monthly resolution for the period 1602-2003 AD, and the Last Millennium Reanalysis (LMR) version 2, which has an annual resolution from 0-2000 AD. We apply maximum covariance and empirical orthogonal function analyses on these two datasets to reveal co-varying patterns of Arctic upper-tropospheric changes and the GrIS surface conditions over centennial and millennial timescales with a special focus on remote tropical drivers of this local coupling. In light of these tropical-Arctic linkages in shaping GrIS conditions over the past two millennia, the application of proxy-assimilated model experiments provides deeper insights into the formation of such atmospheric dynamical connections that may impact GrIS in the future.