The Snow Line and Climate during the Last Glacial Period in the Andes Mountains
The Snow Line and Climate during the Last Glacial Period in the Andes Mountains
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安第斯山脉末次冰期的雪线与气候
DOI：
10.4116/jaqua.11.71
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发表时间：
1972
期刊：
影响因子：
--
通讯作者：
M. Nogami
中科院分区：
文献类型：
--
作者：
M. Nogami
本文的目的是根据现在的雪线与现在的环流模式的关系，从以前的雪线推断威斯康星州安第斯山脉末次冰期的大气环流模式。以前的雪线是根据冰斗最低底部的高度重建的。数据来自我自己的实地观察、地图解释和一些作者的文献。雪线高度分布图如图1所示，广义经向剖面图如图2所示。现雪线（PSL）曲线在副热带高压带中心处取最大值。 PSL 和威斯康星州雪线 (WSL) 之间的最高点位置没有明显差异。 PSL 从最高点突然下降到纬度。南纬 40°，从那里缓缓到达南极。雪线梯度的断点与雨带北界重合，全年西风带降水较多。它也没有动。而且安第斯山脉大部分地区的WSL与PSL似乎有些平行。从上述事实可以看出，威斯康星冰河期的大气环流格局与现在的格局大致相同，安第斯地区的威斯康星雪线凹陷并不是由于气候带转移导致的降水量增加造成的，而主要是由于大气变冷造成的。它。可以认为，北半球气候带的明显变化是冰河时期大陆冰盖巨大扩张引起的次生现象。
It is the purpose of this paper to infer the atomospheric circulation pattern in the Andes Mountains during the last glacial period, Wisconsin, from the former snow line, on the basis of relationship of the present snow line to the present circulation pattern. The former snow line was reconstructed from the altitude of lowest cirque bottoms. Data were obtained from my own field observations, map interpretations and literatures of some authors. Hights of snow line are shown as distribution map in Fig. 1 and as generalized meridional section in Fig. 2.The curve of present snow line (PSL) takes a maximum value in the center of the subtropical high pressure belt. No difference is apparent in the position of the maximum point between PSL and Wisconsin snow line (WSL). PSL drops abruptly from the maximum point to lat. 40°S, and gently from there to the south pole. This break point in the snow line gradient coincides with the northern limit of the rainy zone where we have much precipitation by westerlies throughout the year. It did not move either. And WSL appears to be somewhat in parallel with PSL for the most part of the Andes Mountains.From the facts described above, it can be concluded that the atomospheric circulation pattern during the Wisconsin glacial period was much the same as the present pattern, and that the Wisconsin snow line depression in the Andean sector was not caused by increasing of precipitation, which would be resulted from climatic zone shift, but mostly by cooling of atomosphere. It. may be considered that the distinctive shift of climatic zones in the Northern Hemisphere was a secondary phenomena caused by enormous expansion of continental ice sheets in the glacial period.