Characteristics of Recent Glacier Variations in Patagonia, Southern Andes

1993年11月和12月，在南美洲安第斯山脉南部南巴塔哥尼亚冰原的Upsala、Moreno和Tyndall冰川进行了冰川学研究。完成的研究大纲如下：1。在上述三个冰川消融区，采用三角测量法测量冰川表面高度。通过对比1990年11 - 12月的资料发现，近3年来Upsala冰川从30米变薄到45米，Tyndall冰川从10米变薄到15米。而莫雷诺冰川几乎一直处于稳定状态。测量了莫雷诺冰川和乌普萨拉冰川冰流速度的分布和短期变化。在莫雷诺冰川边缘附近的一个点上，速度在0.4到1.2厘米/小时之间波动。采用应变网格法对Moreno和Tyndall冰川表面应变率进行了研究。1993年12月底完成了对北巴塔哥尼亚冰原周围的空中调查。利用倾斜航拍资料，分析了近20个出口冰川锋面位置的变化。大多数冰川已大幅退缩。在1993年11月和12月分别对莫雷诺冰川和廷德尔冰川的裸冰进行了15天和15天的气象参数和冰的消融速率观测。讨论了气象条件和热平衡的特点。地貌学研究在Ameghino山谷、Upsala冰川终点周围和Tyndall冰川东部地区进行。获得了许多关于最近冰川变化的信息。

Glaciological researches were carried out in November and December 1993, at Upsala, Moreno and Tyndall glaciers in the Southern Patagonia Icefield, southern Andes in South America. Outline of the studies accomplished is as follows :1. Measurements of glacier surface heights were made by a triangulation method in the ablation areas of the above three glaciers. By comparing the data obtained in November-December 1990, it was found that Upsala Glacier has thinned from 30 to 45 m and Tyndall Glacier has thinned from 10 to 15 m during the last three years. Whereas Moreno Glacier has been almost in a steady state.2. Distributions and short-term variations of ice flow velocities were measured at Moreno and Upsala glaciers. Velocities fluctuated from 0.4 to 1.2 cm/hour at a point near the margin of Moreno Glacier. Strain rates of glacier surface were also obtained at Moreno and Tyndall glaciers by a strain grid method.3. An aerial survey around the Northern Patagonia Icefield was accomplished in the end of December 1993. Using the oblique aerial photographs taken, variations of frontal positions of about 20 outlet glaciers are analyzed. Most glaciers have retreated considerably.4. Meteorological parameters and ablation rates of ice were observed on the bare-ice of Moreno and Tyndall glaciers during the periods of 15 days in November and 15 days in December 1993, respectively. Characteristics of meteorological conditions and heat balance are discussed.5. Geomorphological research was carried out in the Ameghino Valley, around the terminus of Upsala Glacier and in the eastern area of Tyndall Glacier. Much information of the recent glacier variations was obtained.