The Relationship Between Submarine Melt and Subglacial Discharge From Observations at a Tidewater Glacier
The Relationship Between Submarine Melt and Subglacial Discharge From Observations at a Tidewater Glacier
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DOI：
10.1029/2021jc018204
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发表时间：
2022-10-01
影响因子：
3.6
通讯作者：
Kienholz, Christian
中科院分区：
文献类型：
--
作者：
Jackson, Rebecca H.;Motyka, Roman J.;Kienholz, Christian
在潮汐水冰川末端，海洋冰川相互作用铰链铰链的两个淡水 - 马林融化和冰山下排放的来源上，这些淡水通量通常在其大小，季节性和关系中不受限制。通过测量海洋速度，温度和盐度，可以评估峡湾预算，以将淡水通量划分为海底融化和冰山下排放。我们在2016 - 2018年的六次调查中，应用这些方法来计算阿拉斯加Leconte冰川的淡水通量，在各种海洋和大气条件下进行计算。我们将这些海洋衍生的通量与从表面质量平衡模型中的冰川放电以及对多片声声纳和自主皮划艇的海底熔体估计的估计值进行了比较，从而发现了这些独立估计之间相对较好的一致性。在春季，夏季和秋季，冰川排放和海底熔体之间的关系遵循标准理论预测的缩放定律（熔体类似于排放（1/3）），尽管熔体的总幅度比理论大的数量级大。估计。冰山下排放是熔体变异性的主要驱动力，而熔体对峡湾性质的依赖性是不可分割的。对海洋预算与冰川记录的比较表明，在春季，夏季和秋季期间，海底融化将冰的33％-49％移至终点站。因此，熔体是冰川质量平衡的重要组成部分，我们发现熔体与季节性撤退相关。但是，熔体似乎并没有直接扩大产犊。
At tidewater glacier termini, ocean-glacier interactions hinge on two sources of freshwater-submarine melt and subglacial discharge-yet these freshwater fluxes are often unconstrained in their magnitude, seasonality, and relationship. With measurements of ocean velocity, temperature and salinity, fjord budgets can be evaluated to partition the freshwater flux into submarine melt and subglacial discharge. We apply these methods to calculate the freshwater fluxes at LeConte Glacier, Alaska, across a wide range of oceanic and atmospheric conditions during six surveys in 2016-2018. We compare these ocean-derived fluxes with an estimate of subglacial discharge from a surface mass balance model and with estimates of submarine melt from multibeam sonar and autonomous kayaks, finding relatively good agreement between these independent estimates. Across spring, summer, and fall, the relationship between subglacial discharge and submarine melt follows a scaling law predicted by standard theory (melt similar to discharge(1/3)), although the total magnitude of melt is an order of magnitude larger than theoretical estimates. Subglacial discharge is the dominant driver of variability in melt, while the dependence of melt on fjord properties is not discernible. A comparison of oceanic budgets with glacier records indicates that submarine melt removes 33%-49% of the ice flux into the terminus across spring, summer, and fall periods. Thus, melt is a significant component of the glacier's mass balance, and we find that melt correlates with seasonal retreat; however, melt does not appear to directly amplify calving.