The Trans-Sierra Climatic Contrast

气候和环境响应的区域模式 北美西南部在关键的千年的结束， 区域格局与更新世关系 全球气候变化仍然是国家和国际 重要的研究课题。 内华达山脉：位于加州东部的内华达山脉 今天是一个主要的气候和植被边界，但在年底 在最后一个冰河时代，像大盆地一样的植被覆盖着较低的山坡， 位于内华达州南部的山脉两侧。 本工程 调查人员将收集、测定年代和检查湖芯年表 从加州东部的塞拉克雷斯以西的四湖中采集 评估两个相互竞争的假设，解释为什么西方 塞拉利昂是干燥和东部塞拉利昂是潮湿的结束时， 末次冰期 第一个假设认为， 季风活动是由于更大的夏季日照和增强 海陆温差 第二种选择解释了 北方干旱和南方干旱 冬季急流的影响 该研究将有助于我们对晚第四纪的认识 干旱的北美植被历史和气候模式， 影响了它。这些知识将增加我们对 气候和植被变化的过程以及区域 变化涉及全球变化。

Regional patterns of climate and environmental response in southwestern North America during the pivotal millennia of the end of the Pleistocene epoch, and the relations of that regional pattern to global climate change continue to be nationally and internationally important research topics. The Sierra Nevadas of eastern California are a major climatic and vegetational boundary today, but at the end of the last ice age Great Basin-like vegetation coverered lower slopes on both sides of the southern Sierra Nevada. In this project, the investigator will collect, date, and examine lake-core chronologies from four lakes west of the Sierra crest in eastern Calfornia in order to evaluate two competing hypotheses that explain why the western Sierra was drier and the eastern Sierra was wetter at the end of the last glacial period. The first hypothesis argues that enhanced monsoonal activity was due to greater summer insolation and an enhanced land-sea thermal contrast. The second alternative explains the northern aridity and the southern moistness by a southward displacement of the winter jet stream. The study will illuminate our understanding of the late Quaternary vegetation history of arid North America and the climatic patterns that have influenced it. This knowledge will increase our understanding of processes of climatic and vegetation change and the ways the regional changes relate to global changes.