Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield
Seasonal Variations in Ice-Front Position Controlled by Frontal Ablation at Glaciar Perito Moreno, the Southern Patagonia Icefield
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DOI：
10.3389/feart.2017.00001
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发表时间：
2017-01-24
影响因子：
2.9
通讯作者：
Skvarca, Pedro
中科院分区：
文献类型：
--
作者：
Minowa, Masahiro;Sugiyama, Shin;Skvarca, Pedro
崩解冰川的锋面位置受冰速和锋面消融的控制，消融包括消融和消融两个过程。然而，这些过程在锋面变化中的相对重要性很难评估，也很难理解，特别是对于淡水崩解的冰川。为了更好地了解淡水崩解冰川冰锋变化的季节变化机制，我们测量了巴塔哥尼亚冰川Perito Moreno冰川的冰锋位置、冰面速度、气温和冰川湖温。尽管气温有变暖趋势(0.059摄氏度a(-1))，但在所研究的15年期间(1999年至2013年)，锋面位置和冰速没有出现实质性波动。冰锋位置(+/-50m)和冰速(+/-15%)都有季节变化。根据锋面位移率和冰速计算出的锋面消融率具有季节性变化，其幅度约为冰速的5倍。锋面消融与湖水温度季节变化有很好的相关性(r=0.96)，而与气温的相关性不大(r=0.86)。我们的发现表明，冰川Perito Moreno冰锋的季节性变化主要是由于冰锋消融，而锋面消融是受湖泊热条件控制的水下融化。
The front position of calving glaciers is controlled by ice speed and frontal ablation which consists of the two processes of calving and subaqueous melting. However, the relative importance of these processes in frontal variation is difficult to assess and poorly understood, particularly for freshwater calving glaciers. To better understand the mechanism of seasonal variations involved in the ice front variations of freshwater calving glaciers, we measured front position, ice surface speed, air temperature, and proglacial lakewater temperature of Glaciar Perito Moreno in Patagonia. No substantial fluctuations in front position and ice speed occurred during the 15-year period studied (1999-2013), despite a warming trend in air temperature (0.059 degrees C a(-1)). Seasonal variations were observed both in the ice-front position (+/- 50 m) and ice speed (+/- 15%). The frontal ablation rate, computed from the frontal displacement rate and the ice speed, varied in a seasonal manner with an amplitude approximately five times greater than that in the ice speed. The frontal ablation correlated well with seasonal lakewater temperature variations (r = 0.96) rather than with air temperature (r = 0.86). Our findings indicate that the seasonal ice front variations of Glaciar Perito Moreno are primarily due to frontal ablation, which is controlled through subaqueous melting by the thermal conditions of the lake.