Department of Oceanography, Texas A&M University, College Station, TX 77843, USA.
Science. 2012 Sep 28;337(6102):1629-33. doi: 10.1126/science.1218390.
The water cycle in the western United States changed dramatically over glacial cycles. In the past 20,000 years, higher precipitation caused desert lakes to form which have since dried out. Higher glacial precipitation has been hypothesized to result from a southward shift of Pacific winter storm tracks. We compared Pacific Ocean data to lake levels from the interior west and found that Great Basin lake high stands are older than coastal wet periods at the same latitude. Westerly storms were not the source of high precipitation. Instead, air masses from the tropical Pacific were transported northward, bringing more precipitation into the Great Basin when coastal California was still dry. The changing climate during the deglaciation altered precipitation source regions and strongly affected the regional water cycle.
美国西部的水循环在冰期循环中发生了巨大变化。在过去的 20000 年里，更高的降水导致了沙漠湖泊的形成，而这些湖泊后来已经干涸了。有人假设，更高的冰川降水是由于太平洋冬季风暴轨迹向南移动造成的。我们将太平洋数据与西部内陆的湖泊水位进行了比较，发现大盆地的高湖相期比同一纬度的沿海湿润期更早。西风风暴并不是高降水的来源。相反，热带太平洋的气团被向北输送，当加利福尼亚沿海地区仍然干燥时，更多的降水被带入大盆地。冰川消退期间气候变化改变了降水源区，并强烈影响了区域水循环。
