Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniques. Both monthly and daily timescale changes in T and P are addressed, the latter being important for a range of applications in energy use, water management, and agriculture. The T changes tend to agree more across downscaling techniques than the P changes. Year-to-year natural internal climate variability is roughly of similar magnitude to the projected T changes. In the monthly average, July temperatures shift enough that that the hottest July found in any simulation over the historical period becomes a modestly cool July in the future period. Januarys as cold as any found in the historical period are still found in the 2060s, but the median and maximum monthly average temperatures increase notably. Annual and seasonal P changes are small compared to interannual or intermodel variability. However, the annual change is composed of seasonally varying changes that are themselves much larger, but tend to cancel in the annual mean. Winters show modestly wetter conditions in the North of the state, while spring and autumn show less precipitation. The dynamical downscaling techniques project increasing precipitation in the Southeastern part of the state, which is influenced by the North American monsoon, a feature that is not captured by the statistical downscaling. 相似文献
识别全新世气候事件、阐明其区域环境表现特征、揭示其驱动机制是理解气候系统变化行为、预测未来气候变化以及弄清考古学文化转变动因的关键,具有重要的科学价值和现实意义。随着高分辨率全新世古气候重建的进展,7.5~7.0 cal.ka B. P.事件逐渐被揭示,但到目前为止仍缺乏针对该气候事件各种类型证据的系统收集、对比以及对其产生动力机制的分析。本文基于中国26条古气候记录,系统总结了这一气候事件在中国地区的环境表现。结果显示,7.5~7.0 cal.ka B. P.气候事件在中国多个地区都有明显的反映,整体表现为温度下降、夏季风强度减弱。与全球其他地区的古气候记录对比显示7.5~7.0 cal.ka B. P.气候事件可能具有全球性的特征。与驱动因子系列对比发现该气候事件发生在北半球夏季太阳辐射逐渐减少、太阳活动减弱、火山活动频发、劳伦泰德冰盖快速融化期间,表明这4种因素在7.5~7.0 cal.ka B. P.气候事件发生过程中发挥了作用。未来需要更多测年准确、分辨率高的古气候记录定量-半定量刻画该气候事件的变化幅度、起止时间以及区域差异,同时结合古气候模拟揭示7.5~7.0 cal.ka B. P.气候事件产生的动力机制。