Antarctic Atmospheric Rivers in Present and Future Climates

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• Michelle Maclennan (University of Colorado Boulder)
• Friday 20 September 2024, 14:00-15:00
• BAS Cambridge Meeting Room 154 and Zoom.

If you have a question about this talk, please contact Thomas Caton Harrison.

Despite their relative rarity, atmospheric rivers (ARs) are key contributors to the surface mass balance of Antarctica. However, the future role of ARs in the Antarctic climate system, and in particular their ability to help offset future Antarctic mass loss by producing intense precipitation, is a major area of uncertainty. High-resolution climate simulations from the Community Earth System Model version 2 (CESM2) large ensemble suggest that Antarctic ARs are highly sensitive to future increases in atmospheric moisture, which leads to a doubling of AR frequencies and precipitation impacts from 2066-2100 (under the Shared Socioeconomic Pathway 3-7.0) when using present-day thresholds for AR detection. However, future surface impacts are critically dependent on the detection threshold for ARs: accounting for moisture increases in the threshold produces smaller, regional changes in AR frequency and precipitation, primarily resulting from an eastward shift of the polar jet. Ultimately, this work shows that how we detect Antarctic ARs and attribute precipitation in the present day, and how we adapt these methodologies to future climate states, will determine how we describe the importance of ARs in the Antarctic climate system. Furthermore, the results underline the importance of using model large ensembles to quantify Antarctic AR responses to variability in projected moisture, which may not be captured when using only a few ensemble members.

This talk is part of the BAS Atmosphere, Ice and Climate Seminars series.

This talk is included in these lists:

• BAS Atmosphere, Ice and Climate Seminars
• BAS Cambridge Meeting Room 154 and Zoom

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