Impact of atmospheric rivers on Arctic sea ice variations

February 5, 2024

A new paper titled “Impact of atmospheric rivers on Arctic sea ice variations” led by Linghan Li with co-authors Forest Cannon (Tomorrow.io), Matthew Mazloff (UCSD), Aneesh Subramanian (University of Colorado Boulder), Anna Wilson (CW3E), and Fred Martin Ralph (CW3E Director), was recently published in the European Geosciences Union’s journal The Cryosphere. This paper examines how atmospheric rivers (ARs) contribute to variations in Arctic sea ice, which has been rapidly decreasing especially in the summer in recent decades. The research first focuses on physical processes in two case studies of ARs in 2012 and 2020, then expands to a larger statistical analysis for 1981-2020 over the entire Arctic Ocean. This research contributes to the Atmospheric River Research and Applications, and the Monitoring and Projections of Climate Variability and Change Priority Areas in CW3E’s 2019-2024 Strategic Plan by adding to the understanding of the global impacts of atmospheric rivers and the relationship with climate change in polar regions.

Li uses hourly data at 0.25° × 0.25° resolution from ERA5, the most recent atmospheric reanalysis from ECMWF, to study causal relationships between ARs and decreases in sea ice concentration. In August 2012 and July 2020, ARs associated with large cyclones triggered rapid sea ice melt through modulating turbulent heat fluxes and winds. In a statistical analysis on weather timescales, Li finds a significant negative correlation between atmospheric moisture content and the rate of changes in sea ice concentration over almost the entirety of the Arctic Ocean (Figure 1, Figure 10 from Li et al. 2024). Ice concentration changes are also shown to be negatively correlated with northward winds and with latent and sensible heat fluxes. The work demonstrates how conditions associated with ARs play an important role in the changing Arctic sea ice cover.

Figure 1: (Figure 10 from Li et al. 2024) (a) Rank correlation between anomalies of IWV and sea ice concentration tendency. Only significant correlations are plotted. (b) Rank correlation between anomalies of northward wind and sea ice concentration tendency. (c) Rank correlation between anomalies of latent heat flux and sea ice concentration tendency. (d) Rank correlation between anomalies of sensible heat flux and sea ice concentration tendency.

Li, L., Cannon, F., Mazloff, M. R., Subramanian, A. C., Wilson, A. M., & Ralph, F. M. (2024). Impact of atmospheric rivers on Arctic sea ice variations. The Cryosphere, 18(1), 121-137. https://doi.org/10.5194/tc-18-121-2024