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Understanding the Role of Atmospheric Rivers in Arctic Moisture Variability
In recent years, the Arctic has experienced significant warming, a phenomenon referred to as Arctic amplification. This change has profound implications for the region’s cryosphere, ecosystems, and the global climate, influencing atmospheric circulation patterns worldwide.
The Clausius-Clapeyron relationship indicates that as temperatures rise, the atmosphere’s capacity to hold moisture increases. This added water vapor not only acts as a greenhouse gas but also exacerbates the warming of the Arctic via various feedback loops.
Atmospheric rivers (ARs), which are narrow bands of concentrated moisture in the atmosphere, play a crucial role in moisture transport towards the poles. Even though they constitute only about 10% of atmospheric activity, they are responsible for roughly 90% of the moisture that moves toward polar regions.
While ARs primarily occur in mid-latitude regions, their impact on the Arctic can be pronounced, especially during the summer months when the amount of moisture from these rivers peaks. Nonetheless, the exact mechanisms that dictate the variability of ARs remain poorly understood, particularly regarding their long-term contributions to Arctic moisture.
A recent study published in Nature Communications by an international collaborative team from China, the U.S., Chile, and Belgium explores these interactions.
The researchers identified a notable spatiotemporal relationship between ARs and various atmospheric parameters, including specific humidity, circulation patterns, and temperature across different time frames. This suggests that common physical processes govern these elements. Importantly, the study highlights that the long-term changes in summer moisture levels in the Arctic due to ARs cannot be solely linked to human-induced climate change, as shown by model responses.
According to the findings, large-scale atmospheric circulation patterns in the Arctic have a significant bearing on AR activity.
Prof. Qinghua Ding of the University of California, Santa Barbara, who led the research, remarked, “In recent decades, ARs have been responsible for an increased influx of water vapor to the Arctic, which has often been attributed to global warming and Arctic amplification. Our study suggests that this increase is largely driven by natural internal variability rather than direct human influence.”
By isolating moisture contributions from ARs, the study revealed that since 1979, over 36% of the rising summer water vapor in the Arctic can be traced back to ARs. This impact is especially pronounced in areas with heightened AR activity, including western Greenland, northern Europe, and eastern Siberia, where it surpasses 50%.
Dr. Wang Zhibiao from the Institute of Atmospheric Physics at the Chinese Academy of Sciences, the lead author of the study, commented, “While ARs are typically perceived as random, extreme weather events influenced by larger systems, they significantly regulate water vapor variability in the Arctic and are key to understanding long-term moisture changes.”
More information: Zhibiao Wang et al, “Role of atmospheric rivers in shaping long term Arctic moisture variability,” Nature Communications (2024). DOI: 10.1038/s41467-024-49857-y
This research emphasizes the complexity of climate interactions, particularly in the Arctic, and underlines the need for further investigation into how natural variability and human activities intertwine to influence regional and global climates.
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phys.org