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Modeled impact of cirrus cloud increases along aircraft flight paths

机译：卷云的模拟影响沿飞机飞行路径增加

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The potential climate impact of contrails and alterations in the lifetime of background cirrus due to subsonic aircraft water and aerosol emissions has been investigated in a set of experiments using the GISS GCM connected to a q-flux ocean. Cirrus clouds at a height of 12-15 km, with an optical thickness of 0.33, were input to the model "x" percentage of clear-sky occasions along subsonic aircraft flight paths. The percentage x is varied from 0.05 to 6%. Two types of experiments were performed: one with the percentage of cirrus cloud increase independent of flight density along the flight paths, the other with the percentage related to the density of fuel expenditure. The overall climate impact was similar with the two approaches. due to the feedbacks of the climate system. Fifty years were run for each of the eight experiments, with the following conclusions based on the stable results from years 31-50. The equilibrium global mean response shows that altering high-level clouds by 1% changes the global mean temperature by 0.43 degrees C. The global temperature response is highly linear (linear correlation coefficient of 0.996) for high cloud cover changes between 0.1 and 5%. The warming is amplified in the Northern Hemisphere, more so with greater cloud cover change. The temperature effect maximizes around 10 km, more so as the overall warming increases (warming greater than 4 degrees C occurs there with a 4.8% increase in upper level clouds). The surface temperature response is dominated by the feedbacks and shows little geographic relationship to the high cloud input outside of the hemispheric difference. Considering whether these effects would be observable, changing upper level cloud cover by as little as 0.4% produces warming greater than 2 standard deviations in the microwave sounding unit (MSU) channels 4, 2, and 2r (although the effect would be most noticeable in the upper troposphere channel 3 were standard deviations available). Given estimates of current aircraft impacts, this would require some increase relative to present-day effects, but a signal should be clear given the projections for 2050 aircraft. In comparison to increased CO2 experiments, in these runs the Northern Hemisphere clearly warms more relative to the Southern Hemisphere, and warming due to cloud height changes exceeds that due to the water vapor feedback. Despite the simplified nature of these experiments, the results emphasize the sensitivity of the modeled climate to high-level cloud cover changes and thus the potential ability of aircraft to influence climate by altering clouds in the upper troposphere. [References: 28]
机译：使用与Q-通量海洋相连的GISS GCM进行的一组实验研究了由于亚音速飞机水和气溶胶排放而引起的轨迹转换和背景卷云寿命改变对气候的潜在影响。沿着亚音速飞机飞行路径，将高度为12-15 km，光学厚度为0.33的卷云输入到模型“ x”百分比的晴朗天空场合。 x的百分比在0.05至6％之间变化。进行了两种类型的实验：一种是卷云的增加与沿飞行路径的飞行密度无关，另一种是与燃料消耗的密度有关的百分比。两种方法对气候的总体影响相似。由于气候系统的反馈。八个实验各运行了五十年，基于31至50年的稳定结果得出以下结论。平衡的全局平均响应表明，将高层云量改变1％，会使全局平均温度变化0.43摄氏度。对于高云量变化在0.1％和5％之间，全局温度响应是高度线性的（线性相关系数为0.996）。北半球的变暖加剧，云量变化更大。温度效应在大约10 km处最大化，并随着整体变暖的增加而增加（在此处，升温超过4摄氏度，高层云增加4.8％）。表面温度响应主要受反馈影响，并且与半球差异之外的高云输入几乎没有地理关系。考虑到这些影响是否可以观察到，将低层云层的变化降低至0.4％会在微波探测单元（MSU）通道4、2和2r中产生大于2个标准差的变暖（尽管这种影响最明显）对流层上方通道3是可用的标准差）。根据对当前飞机影响的估计，这将需要相对于目前的影响有所增加，但是鉴于2050年飞机的预测，应该明确一个信号。与增加的二氧化碳实验相比，在这些运行中，北半球相对于南半球明显变暖，并且由于云层高度变化而引起的变暖超过了因水蒸气反馈而引起的变暖。尽管这些实验具有简化的性质，但结果仍强调了模拟气候对高空云量变化的敏感性，因此飞机通过改变对流层高层的云层来影响气候的潜在能力。 [参考：28]

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