Characteristics of Recent Glacier Variations in Patagonia, Southern Andes

冰川学研究于1993年11月和12月在南美洲南部安第斯山脉南部巴塔哥尼亚冰原的Upsala、Moreno和Tyndall冰川进行。已完成的研究概述如下：1.在上述三个冰川消融区，用三角测量法测量了冰川表面高度。通过比较1990年11-12月的资料，发现近三年来厄普萨拉冰川厚度从30米减至45米，廷德尔冰川从10米减至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。莫雷诺冰川边缘附近某点的速度在0.4-1.2厘米/小时之间波动。用应变网格法得到了莫雷诺冰川和廷德尔冰川冰川表面的应变率。巴塔哥尼亚北部冰原周围的空中勘测于1993年12月底完成。利用所拍摄的倾斜航片，分析了约20个出口冰川锋面位置的变化。大多数冰川已经相当程度上消退了。观测了1993年11月15日和12月15日期间莫雷诺冰川和廷德尔冰川裸露冰的气象参数和消融率。讨论了气象条件和热量平衡的特点。地貌研究是在阿梅吉诺山谷、厄普萨拉冰川末端周围和廷德尔冰川东部地区进行的。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.