2023-11-07 ペンシルベニア州立大学(PennState)
◆彼らは西南極のアムンセン海の海氷減少の影響を分析し、海氷の不在が大気中の湿度と氷床への大雪を増加させることを発見した。追加の降雪は氷の融解などの影響を完全に相殺するほどではないが、気候モデルに組み込むことで海面上昇などの予測の改善に役立つ可能性があります。
◆南極の雪の降水の主要な源は周囲の海洋からの蒸発で、海氷はこのプロセスを調節する役割を果たしています。科学者たちは、南極の雪の降水が氷床に及ぼす影響に焦点を当て、これが将来の海面上昇にどのように影響を与えるかを理解しようとしています。
＜関連情報＞
- https://www.psu.edu/news/earth-and-mineral-sciences/story/melting-ice-falling-snow-sea-ice-declines-enhance-snowfall-over/
- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023GL104436
海氷変動が西南極の気候と地表面物質収支に与える影響を明らかにする Identifying the Impacts of Sea Ice Variability on the Climate and Surface Mass Balance of West Antarctica
Jessica D. Kromer, Luke D. Trusel
Geophysical Research Letters Published: 13 September 2023
DOI:https://doi.org/10.1029/2023GL104436
Abstract
The Antarctic ice sheet (AIS) is the largest freshwater body on Earth and a major component of the sea level budget. Over the satellite era, the AIS has experienced ∼130 Gt/year of mass loss. Net losses are partially mitigated by snow accumulation that varies ∼100–130 Gt/yr, underscoring a need to understand the drivers of snowfall variability. Here, we evaluate impacts of decreased sea ice in the Amundsen Sea region of West Antarctica on the overlying atmosphere and surface mass balance of the adjacent AIS using composites, spatial correlations, and a causal effect network method. Importantly, our findings show sea ice declines in the Amundsen Sea lead to enhanced integrated water vapor that is subsequently transported to the AIS resulting in positive anomalies in West Antarctic ice sheet snowfall. Our results suggest future decreases in sea ice may likely enhance ice sheet snowfall, thus partially offsetting Antarctic sea level contributions.
Key Points
- Observations and reanalyzes reveal decreased sea ice leads to increased precipitation over the West Antarctic ice sheet
- Causal discovery links low sea ice to enhanced water vapor and precipitation-bearing clouds over the ice sheet
- Past and future changes in sea ice hold implications for ice sheet surface mass balance
Plain Language Summary
The Antarctic ice sheet (AIS) is the largest freshwater body on Earth and is a major component of the sea level budget. Since the start of the satellite record in 1980, the AIS has been losing mass at an increasing rate. These losses are attributed to increased flow of ice into the ocean and are partially balanced each year by the accumulation of snow across the ice sheet’s surface. The degree to which it snows across Antarctica therefore controls how much the ice sheet contributes to sea level in any given year. Thus, it is crucial for us to understand the drivers of snowfall variability. Here, we evaluate the impacts of decreased sea ice in the Amundsen Sea region of West Antarctica on snowfall over the adjacent ice sheet. Importantly, our findings show that sea ice declines in this region lead to enhanced moisture in the atmosphere which is then transported over the West Antarctic ice sheet resulting in greater snowfall.
