# Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean

The Pacific sector of the Arctic Ocean (PA, hereafter) is a region sensitive to climate change. Given the alarming changes in sea ice cover during recent years, knowledge of sea ice loss with respect to ice advection and melting processes has become critical. With satellite-derived products from the National Snow and Ice Center (NSIDC), a 38-year record (1979–2016) of the loss in sea ice area in summer within the Pacific-Arctic (PA) sector due to the two processes is obtained. The average sea ice outflow from the PA to the Atlantic-Arctic (AA) Ocean during the summer season (June–September) reaches inline-formula0.173×106 kminline-formula2, which corresponds to approximately 34 % of the mean annual export (October to September). Over the investigated period, a positive trend of inline-formula0.004×106 kminline-formula2 yrinline-formula−1 is also observed for the outflow field in summer. The mean estimate of sea ice retreat within the PA associated with summer melting is inline-formula1.66×106 kminline-formula2, with a positive trend of inline-formula0.053×106 kminline-formula2 yrinline-formula−1. As a result, the increasing trends of ice retreat caused by outflow and melting together contribute to a stronger decrease in sea ice coverage within the PA (inline-formula0.057×106 kminline-formula2 yrinline-formula−1) in summer. In percentage terms, the melting process accounts for 90.4 % of the sea ice retreat in the PA in summer, whereas the remaining 9.6 % is explained by the outflow process, on average. Moreover, our analysis suggests that the connections are relatively strong (inline-formulaR=0.63), moderate (inline-formula $M15inlinescrollmathmlR=-normal 0.46$ 52pt10ptsvg-formulamathimg4f9f533dc4b1268318e991872a7b2e14 tc-13-1423-2019-ie00001.svg52pt10pttc-13-1423-2019-ie00001.png ), and weak (inline-formula $M16inlinescrollmathmlR=-normal 0.24$ 52pt10ptsvg-formulamathimgeaa0dff95117737796b4c60d4a76287d tc-13-1423-2019-ie00002.svg52pt10pttc-13-1423-2019-ie00002.png ) between retreat of sea ice and the winds associated with the dipole anomaly (DA), North Atlantic Oscillation (NAO), and Arctic Oscillation (AO), respectively. The DA participates by impacting both the advection (inline-formulaR=0.74) and melting (inline-formulaR=0.55) processes, whereas the NAO affects the melting process (inline-formula $M19inlinescrollmathmlR=-normal 0.46$ 52pt10ptsvg-formulamathimg55f9c6455fa1e60f5f64769b5b88a549 tc-13-1423-2019-ie00003.svg52pt10pttc-13-1423-2019-ie00003.png ).

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Bi, Haibo / Yang, Qinghua / Liang, Xi / et al: Contributions of advection and melting processes to the decline in sea ice in the Pacific sector of the Arctic Ocean. 2019. Copernicus Publications.

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