Clement Amy C, Burgman Robert, Norris Joel R
Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Division of Meteorology and Physical Oceanography, MSC 362, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
Science. 2009 Jul 24;325(5939):460-4. doi: 10.1126/science.1171255.
Feedbacks involving low-level clouds remain a primary cause of uncertainty in global climate model projections. This issue was addressed by examining changes in low-level clouds over the Northeast Pacific in observations and climate models. Decadal fluctuations were identified in multiple, independent cloud data sets, and changes in cloud cover appeared to be linked to changes in both local temperature structure and large-scale circulation. This observational analysis further indicated that clouds act as a positive feedback in this region on decadal time scales. The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current-generation climate models. The only model that passed this test simulated a reduction in cloud cover over much of the Pacific when greenhouse gases were increased, providing modeling evidence for a positive low-level cloud feedback.
涉及低层云的反馈仍然是全球气候模型预测不确定性的主要原因。通过研究观测数据和气候模型中东北太平洋上空低层云的变化来解决这个问题。在多个独立的云数据集里识别出了年代际波动，云量的变化似乎与当地温度结构和大尺度环流的变化都有关联。这项观测分析进一步表明，在年代际时间尺度上，云在该地区起到正反馈作用。观测到的云量与区域气象条件之间的关系为检验当代气候模型中云模拟的真实性提供了一种更全面的方法。唯一通过这项测试的模型模拟出，当温室气体增加时，太平洋大部分地区的云量减少，这为低层云的正反馈提供了模型证据。
