Warming of waters in an East Greenland fjord prior to glacier retreat: mechanisms and connection to large-scale atmospheric conditions
Warming of waters in an East Greenland fjord prior to glacier retreat: mechanisms and connection to large-scale atmospheric conditions
复制标题
DOI：
10.5194/tc-5-701-2011
复制
发表时间：
2011-01-01
期刊：
影响因子：
5.2
通讯作者：
Benham, T. J.
中科院分区：
文献类型：
--
作者：
Christoffersen, P.;Mugford, R. I.;Benham, T. J.
1993年和2004年在Kangerdlugssuaq峡湾和邻近海域获得的水文数据与NEMO海洋模拟框架的再分析一起使用，以阐明东格陵兰的水团变化和冰-海洋-大气相互作用。水文数据显示，峡湾含有温暖的亚热带沃茨，2004年的峡湾沃茨比1993年温暖得多。海洋再分析结果表明，2004年峡湾沃茨的暖性与海洋向岸热通量进入外大陆架跨大陆架槽的一个主峰有关。进入该槽的热通量根据与大气的季节性交换以及来自亚热带沃茨的深层季节性侵入而变化。当东北风弱（强）时，这两种机制都有助于高（低）的向岸热通量。在水文数据中可以看到地面加热和亚热带沃茨流入的综合效应，这些数据是在沿岸北风强（1993年）和弱（2004年）的时期之后收集的。后者的数据是在Kangerdlugssuaq冰川长期退缩的早期阶段获得的。我们发现，沿海风的变化根据压力梯度所定义的半永久性的大气高压系统在格陵兰岛和一个持久的大气低位于冰岛附近。这种压力梯度的大小是由冰岛低压位置的纵向变化控制的。
Hydrographic data acquired in Kangerdlugssuaq Fjord and adjacent seas in 1993 and 2004 are used together with reanalysis from the NEMO ocean modelling framework to elucidate water-mass change and ice-ocean-atmosphere interactions in East Greenland. The hydrographic data show that the fjord contains warm subtropical waters and that fjord waters in 2004 were considerably warmer than in 1993. The ocean reanalysis shows that the warm properties of fjord waters in 2004 are related to a major peak in oceanic shoreward heat flux into a cross-shelf trough on the outer continental shelf. The heat flux into this trough varies according to seasonal exchanges with the atmosphere as well as from deep seasonal intrusions of subtropical waters. Both mechanisms contribute to high (low) shoreward heat flux when winds from the northeast are weak (strong). The combined effect of surface heating and inflow of subtropical waters is seen in the hydrographic data, which were collected after periods when along-shore coastal winds from the north were strong (1993) and weak (2004). The latter data were furthermore acquired during the early phase of a prolonged retreat of Kangerdlugssuaq Glacier. We show that coastal winds vary according to the pressure gradient defined by a semi-permanent atmospheric high-pressure system over Greenland and a persistent atmospheric low situated near Iceland. The magnitude of this pressure gradient is controlled by longitudinal variability in the position of the Icelandic Low.