Department of Environmental Science, University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 2010 Mar 9;107(10):4533-8. doi: 10.1073/pnas.0915062107. Epub 2010 Feb 16.
Biogeographical, physiological, and paleoecological evidence suggests that the coast redwood [Sequoia sempervirens (D. Don) Endl.] is closely associated with the presence of summer marine fog along the Pacific coast of California. Here we present a novel record of summer fog frequency in the coast redwood region upon the basis of direct hourly measurements of cloud ceiling heights from 1951 to 2008. Our analysis shows that coastal summer fog frequency is a remarkably integrative measure of United States Pacific coastal climate, with strong statistical connections to the wind-driven upwelling system of the California Current and the broad ocean temperature pattern known as the Pacific Decadal Oscillation. By using a long-term index of daily maximum land temperatures, we infer a 33% reduction in fog frequency since the early 20th century. We present tree physiological data suggesting that coast redwood and other ecosystems along the United States west coast may be increasingly drought stressed under a summer climate of reduced fog frequency and greater evaporative demand.
生物地理学、生理学和古生态学证据表明，海岸红杉（Sequoia sempervirens (D. Don) Endl.）与加利福尼亚太平洋沿岸夏季海洋雾的存在密切相关。在这里，我们根据 1951 年至 2008 年的云层高度直接每小时测量值，提供了海岸红杉地区夏季雾频率的新记录。我们的分析表明，沿海夏季雾的频率是美国太平洋沿海气候的一个非常综合的指标，与加利福尼亚洋流的风生上升系统和被称为太平洋年代际振荡的广泛海洋温度模式有很强的统计学联系。通过使用长期的每日最高陆地温度指数，我们推断自 20 世纪初以来，雾的频率减少了 33%。我们提出了树木生理数据，表明随着夏季雾频率降低和蒸发需求增加，美国西海岸的海岸红杉和其他生态系统可能面临更大的干旱压力。
