Modeling the impact of glacial runoff on fjord circulation and submarine melt rate using a new subgrid-scale parameterization for glacial plumes
Modeling the impact of glacial runoff on fjord circulation and submarine melt rate using a new subgrid-scale parameterization for glacial plumes
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DOI：
10.1002/2014jc010324
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发表时间：
2015-02-01
影响因子：
3.6
通讯作者：
Nienow, Peter
中科院分区：
文献类型：
--
作者：
Cowton, Tom;Slater, Donald;Nienow, Peter
冰盖径流向峡湾的深层注入可能是控制冰川锋面融化速率的重要因素。在这里，我们在马萨诸塞州理工学院大气环流模式（MITgcm）中开发了一个新的冰缘羽流参数化，允许在年度（或更长）时间尺度上对大型（500 km（2））冰川峡湾进行三维模拟。我们发现对于理想化的峡湾（没有陆架驱动的环流），冰下径流在水柱的上部产生了一个薄的、强的、温暖的下峡湾流，在更深的地方被一个厚的、缓慢的上峡湾流所平衡。尽管由于羽流与冰锋接触的地方融化速率更高，海底融化速率随着径流而增加，我们发现，每年的海底融化率横跨冰锋是相对不敏感的变化，在年径流。更好地了解径流的空间分布，控制不直接与羽流接触的地区的融化速率，以及连接海底融化和冰山崩解的反馈机制，对于更充分地了解冰川物质平衡对径流驱动的峡湾环流的敏感性是必要的。
The injection at depth of ice sheet runoff into fjords may be an important control on the frontal melt rate of tidewater glaciers. Here we develop a new parameterization for ice marginal plumes within the Massachusetts Institute of Technology General Circulation Model (MITgcm), allowing three-dimensional simulation of large (500 km(2)) glacial fjords on annual (or longer) time scales. We find that for an idealized fjord (without shelf-driven circulation), subglacial runoff produces a thin, strong, and warm down-fjord current in the upper part of the water column, balanced by a thick and slow up-fjord current at greater depth.Although submarine melt rates increase with runoff due to higher melt rates where the plume is in contact with the ice front, we find that annual submarine melt rate across the ice front is relatively insensitive to variability in annual runoff. Better knowledge of the spatial distribution of runoff, controls on melt rate in those areas not directly in contact with plumes, and feedback mechanisms linking submarine melting and iceberg calving are necessary to more fully understand the sensitivity of glacier mass balance to runoff-driven fjord circulation.