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グリーンランド氷床北西部沿岸部における表面質量収支の変動
的場, 澄人;山口, 悟;對馬, あかね;青木, 輝夫;杉山, 慎
Permalink : http://hdl.handle.net/2115/65081
JaLCDOI : 10.14943/lowtemsci.75.37
KEYWORDS : グリーンランド氷床;表面質量収支;アイスコア;SIGMA;GRENE-北極事業
Abstract
グリーンランド氷床北西部における数十年間の表面質量収支を明らかにすることを目的に標高1490 m地点と1750 m地点においてそれぞれ19 mと6.5 m長のアイスコアを採取した．1750 mで採取されたアイスコアは全層乾雪で構成されていた．一方，1490 m地点で採取されたアイスコアは，浅部は表面融解の影響を受けた氷板やザラメ雪層で構成されているのに対し，深部は乾雪で構成されていた．1490 m地点の年間の表面質量収支は，融解の影響が大きくなる2001年以降に減少していた．この地域では，近年降水量の増加が観測されていることから，1490 m地点では表面融解水の流出が生じている可能性が示された．
We conducted shallow ice core drillings at two sites (SIGMA-A: 1490 m a.s.l., SIGMA-A2: 1750 m a.s.l.) on the Greenland Ice Sheet to estimate the past surface mass balance for several decades. The ice cores obtained from the site SIGMA-A2 were composed of dry snow layers. In contrast, the shallower parts of the ice cores obtained from the site SIGMA-A were composed of ice layers and wet snow layers influenced by surface melt water, and the deeper parts were composed of dry snow layers. The reconstructed surface mass balance at the site SIGMA-A decreased since 2001 when melt water influence increased. Because the amount of precipitation in this region has increased recently, we suggest that the low surface mass balance since 2001 indicates that run-off of melt water from the ice sheet has occurred.
We conducted shallow ice core drillings at two sites (SIGMA-A: 1490 m a.s.l., SIGMA-A2: 1750 m a.s.l.) on the Greenland Ice Sheet to estimate the past surface mass balance for several decades. The ice cores obtained from the site SIGMA-A2 were composed of dry snow layers. In contrast, the shallower parts of the ice cores obtained from the site SIGMA-A were composed of ice layers and wet snow layers influenced by surface melt water, and the deeper parts were composed of dry snow layers. The reconstructed surface mass balance at the site SIGMA-A decreased since 2001 when melt water influence increased. Because the amount of precipitation in this region has increased recently, we suggest that the low surface mass balance since 2001 indicates that run-off of melt water from the ice sheet has occurred.
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