2026-09-17 国立極地研究所
東南極に広がる氷河由来の淡水。2012～2024年の海洋観測から推定した氷河由来の淡水の分布（左）と棚氷底面からの融解水量（右）。
＜関連情報＞
端成分に依存しない海洋観測パラメータ化による東南極の氷河由来淡水の三次元復元 Three-dimensional reconstruction of glacier-derived freshwater in East Antarctica using an end-member-independent hydrographic parameterization
Yutaka W. Watanabe, Daisuke Hirano, Yoshihiko Ohashi, Miyabi Sugita, Yoshiyuki Nakano, Ryosuke Makabe & Kohei Mizobata
Nature Communications Published:11 September 2026
DOI:https://doi.org/10.1038/s41467-026-77441-z
Abstract
The melting of the Antarctic Ice Sheet contributes to global sea-level rise and widespread ocean freshening. A major driver of this process is the intrusion of warm deep water onto the continental shelf, which enhances basal melting of ice shelves and weakens their buttressing of inland ice. However, the three-dimensional distribution of glacier-derived freshwater remains poorly constrained in East Antarctica. Here we present a hybrid multiple linear regression–neural network (MLR–NN) framework that reconstructs glacier-derived freshwater from dissolved inorganic carbon (DIC) residuals without prescribing fixed freshwater end-member compositions. Applying this framework to hydrographic observations around the Totten and Moscow University Ice Shelves, we estimate freshwater discharge rates of 70 ± 7 and 53 ± 9 Gt yr⁻¹, respectively. The reconstructed freshwater signal extends across the continental shelf to approximately 64°S. We also identify differences in freshwater discharge between observations collected during the 2010s and the 2020 s, although sparse temporal sampling prevents these differences from being interpreted as a robust long-term trend. Our results provide a three-dimensional observational reconstruction of glacier-derived freshwater in this sector of East Antarctica and demonstrate the potential of an end-member-independent hydrographic parameterization for investigating glacier–ocean interactions in data-limited polar environments.
