Abstract
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.
Highlights
Over recent decades, the Earth’s average surface air temperature has warmed at a rate of ~0.2 °C decade−1 1
The land surface contributes substantially to Arctic vapor concentrations during the spring (33%) and fall (33%) seasons (Supplementary Fig. 2), though detailed analysis of the processes that shape this land-Arctic teleconnection in those seasons is left for future work
The water tracers reveal that most (79%) summer land-based moisture in the Arctic is sourced from latitudes poleward of 45°N and that central and eastern Eurasia contribute more moisture (20 and 27%) than western Eurasia, western North America, or eastern North America (16, 16, and 18%) (Fig. 2b, c)
Summary
The Earth’s average surface air temperature has warmed at a rate of ~0.2 °C decade−1 1. Decreased SIE during the summer and fall seasons allows the Arctic Ocean to absorb more solar radiation and increase the ocean heat content[9,11,12]. This accumulation of heat during nonwinter months enhances winter Arctic amplification in two ways. It limits the pace of sea ice growth in winter, resulting in a greater transfer of ocean heat to the lower atmosphere[9]. Identifying the mechanisms that lead to enhanced sea ice loss during the summer is important for summer Arctic warming, and for winter-time Arctic amplification
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