グリーンランドと南極の氷床の縁で広範囲にわたるダイナミックな薄めが起きている
Hamish D Pritchard1, Robert J Arthern, David G Vaughan
1British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 0ET, UK. hprit@bas.ac.uk
Nature
|September 25, 2009
まとめ
グリーンランドと南極の氷河のダイナミックな薄まりは,海面上昇を加速しています. 高解像度の衛星データは,氷床の縁で海が溶けていくことにより,氷河が広範囲に変化していることを明らかにしています.
科学分野:
- 氷河学 氷河学とは
- 気候科学 気候科学
- 地球観測 地球観測
背景:
- グリーンランドと南極の氷河は加速しており,世界の海面上昇が増加しています.
- ダイナミックな薄め,または加速された氷の流れは,ほとんど理解されず,予測不可能です.
- 以前の衛星センサーでは,急速に流れる沿岸氷河の変化を検出できませんでした.
研究 の 目的:
- グリーンランドと南極の氷床の接地された縁に沿った標高の変化を,高解像度の衛星高度測定を用いてマッピングする.
- 観測された高さの変化と表面質量バランスの変動を比較することによって,ダイナミックな薄れ信号を分離する.
- 両氷床のダイナミックな薄まりの範囲と強さを理解するために.
主な方法:
- 氷,雲,陸地標高衛星 (ICESat) の高解像度レーザー高度測定データを活用しています.
- グリーンランドと南極の氷床の接地された全辺の標高の変化をマッピングする.
- 速く流れる氷とゆっくり流れる氷の標高変化の速度を,表面質量バランスの予想される変化と比較する.
主要な成果:
- グリーンランドの全緯度でダイナミックな薄れが観察され,南極の接地線で強くなっています.
- 氷河の薄化は,氷床の崩壊後の数十年にわたって持続し,内陸の遠くまで浸透します.
- 急速に流れるグリーンランドの氷河 (>100 m yr−1) は平均で0.84 m yr−1で薄くなっており,アムンセン海湾の南極の氷河は9.0 m yr−1.1以上薄くなっている.
結論:
- 海洋によって引き起こされる氷床の融解によって引き起こされるダイナミックな希薄化は,氷床の深い変化の主な原動力である.
- 海辺の氷河の動態は,将来の海面上昇を予測する上で重要な要因である.
- 高解像度衛星高度測定は,これらのダイナミックな氷床のプロセスを監視するために不可欠です.
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