南極の氷河観測で地球観測の最前線を拓く(International Cooperation Helps Advance the Frontiers of Earth Observation)

2025-11-24 ヒューストン大学

ヒューストン大学を含む国際研究チームは、南極の氷河が海水との相互作用により水面下で急速に後退している実態を、高精度レーダー観測と人工衛星データを組み合わせて明らかにした。調査の対象は、氷床融解が世界の海面上昇に大きく寄与するとされるアムンセン海沿岸の氷河群で、特に氷河底面が海水に触れる「接地線」が年単位で後退し、氷河が浮氷棚化して不安定化する傾向が確認された。研究者らは、温暖化に伴う海水の侵入が氷河底を下から侵食し、氷の流動速度を加速させる“海洋駆動型融解”が主要因であると指摘。また、地形が深い盆地状の氷河ほど後退が自己強化し、将来の氷床不安定化が懸念される。こうした変化は氷表面の観測だけでは捉えにくく、研究は今後の海面上昇予測モデル改善に重要なデータを提供している。

南極の氷河観測で地球観測の最前線を拓く(International Cooperation Helps Advance the Frontiers of Earth Observation)
COSMO-SkyMed image of Pine Island Glacier in Antarctica, which clearly shows icebergs of considerable size (the one in the center of the image is almost 9.5 miles) breaking away from the ice shelf formed by the flow of ice into the sea. Photo courtesy Italian Space Agency

<関連情報>

Antarctic grounding line delineation from the Italian Space Agency COSMO-SkyMed DInSAR data

Natalya Ross,Pietro Milillo & Luigi Dini
Scientific Data  Published;03 November 2025
DOI:https://doi.org/10.1038/s41597-025-06023-3

Abstract

This paper presents an Antarctic grounding line dataset, manually mapped using Differential Interferometric Synthetic Aperture Radar (DInSAR) data from the COSMO-SkyMed X-band radar satellite mission. The dataset comprises 794 double difference interferograms with corresponding grounding line products. The data has been collected over 74 glaciers in East Antarctica, West Antarctica, and the Antarctic Peninsula between July 2020 and March 2022. Each DInSAR interferogram was generated using two pairs of radar images, with a one-day interval between images in each pair and acquisition intervals between pairs ranging from 16 to 64 days. The dataset, which relies solely on COSMO-SkyMed data and leverages 1-day repeat-pass interferometry, enables precise grounding line mapping in fast-flowing regions, where sensors like Sentinel-1 and ICESat-2 encounter limitations. This dataset provides extensive coverage across Antarctica and enables the observation of grounding line migrations driven by ocean tides. Furthermore, compared to previously available datasets, it allows for the estimation of long-term retreat rates for several glaciers, including Thwaites, Pine Island, Totten, and Moscow University glaciers.

1702地球物理及び地球化学
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