Extreme moisture transport into the Arctic

Abstract:

The transport of moisture into the Arctic is tightly connected to midlatitude dynamics. We show that the bulk of the transient poleward moisture transport across 60N is driven by extreme transport (fluxes greater than the 90th percentile) events. We demonstrate that this transport is due to “atmospheric rivers” driven largely by synoptic Rossby wave breaking. The results indicate that extreme moisture transport into the Arctic occurs throughout the year, but with a distinct seasonality: the frequency and intensity of the moisture fluxes peak in late-summer, early autumn. On interannual timescales, moisture transport into the Arctic is strongly influenced by climate variability captured by ENSO and the NAO. Possible dynamical drivers of these events and their seasonal and interannual variability are discussed.