Terrestrial sources of summer arctic moisture and the implication for arctic temperature patterns

Sea ice melt and ocean heat accumulation in the Arctic are strongly influenced by the presence of atmospheric water vapor during summer. While the relationships between water vapor concentration, radiation, and surface energy fluxes in the Arctic are well understood, the sources of summer Arctic water vapor are not, inhibiting understanding and prediction of Arctic climate. Here we use the Community Earth System Model version 1.3 with online numerical water tracers to determine the geographic sources of summer Arctic water vapor. We find that on average the land surface contributes 56% of total summer Arctic vapor with 47% of that vapor coming from central and eastern Eurasia. Given the proximity to Siberia, near-surface temperatures in the Arctic between 90°E-150°E, including the Laptev Sea, are strongly influenced by concentrations of land surface-based vapor. Years with anomalously large concentrations of land surface-based vapor in the Arctic, and especially in the Laptev Sea region, often exhibit anomalous near-surface poleward flow from the high latitudes of Siberia, with links to internal variability such as the Arctic Dipole anomaly.

Tyler S. Harrington, Jiang Zhu, Christopher B. Skinner