The new Kr-86 excess ice core proxy for synoptic activity: West Antarctic storminess possibly linked to Intertropical Convergence Zone (ITCZ) movement through the last deglaciation

Here we present a newly developed ice core gas-phase proxy that directly samples a component of the large-scale atmospheric circulation: synoptic-scale pressure variability. Surface pressure changes weakly disrupt gravitational isotopic settling in the firn layer, which is recorded in krypton-86 excess (.sup.86 Kr.sub.xs). The .sup.86 Kr.sub.xs may therefore reflect the time-averaged synoptic pressure variability over several years (site "storminess"), but it likely cannot record individual synoptic events as ice core gas samples typically average over several years. We validate .sup.86 Kr.sub.xs using late Holocene ice samples from 11 Antarctic ice cores and 1 Greenland ice core that collectively represent a wide range of surface pressure variability in the modern climate. We find a strong spatial correlation (r=-0.94, p