Simulated lower stratospheric trends between 1970 and 2005: Identifying the role of climate and composition changes
Simulated lower stratospheric trends between 1970 and 2005: Identifying the role of climate and composition changes
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1970 年至 2005 年间模拟的低平流层趋势：确定气候和成分变化的作用
DOI：
10.1029/2007jd009277
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发表时间：
2008
影响因子：
--
通讯作者：
F. Vitt
中科院分区：
文献类型：
--
作者：
J. Lamarque;D. Kinnison;P. Hess;F. Vitt
[1]我们分析了一组模拟，旨在了解1970年后驱动平流层下部观测趋势的机制。这些模拟是使用社区大气模型第3版（CAM 3）进行的，该版本更新了对流层和平流层的交互化学。即使模型顶部相对较低（1040公里），该模型也显示出良好的能力，能够再现平流层气候和化学成分的各种大规模变化，但必须考虑到观测到的海面温度和表面长寿命痕量气体和臭氧消耗物质的浓度。然后，我们使用相同的模型框架来区分化学活性成分（臭氧，甲烷和氯氟烃）和CO2变化对平流层中观察到的趋势的作用。在分析的敏感性因素中，我们的模拟表明，在模拟期间CO2的变化不会导致显着不同的臭氧总量的趋势，但是，CO2的变化会导致在模型的上部臭氧的重要差异。另一方面，地表甲烷浓度的变化通过对流层和平流层臭氧柱的变化，在推动全球平均总臭氧柱变化方面发挥了重要作用。我们还表明，在热带平均年龄的空气和垂直速度的变化之间的相关性打破了20百帕以上，在该水平以上的等熵混合增加。最后，我们表明，我们的模型是能够再现在其他研究中发现的空气的热带年龄的趋势;我们的模拟还表明，甲烷和臭氧消耗物质保持在1970年的水平显着的影响，表明控制甲烷排放的潜在重要作用。
[1] We have analyzed a set of simulations aimed at understanding the mechanisms that drive observed trends in the lower stratosphere after 1970. The simulations were performed using a version of the Community Atmosphere Model version 3 (CAM3) updated with interactive tropospheric and stratospheric chemistry. Even with a relatively low model top (≈40 km), this model shows good ability at reproducing a variety of large-scale changes in climate and chemical composition in the stratosphere when forced with the observed sea-surface temperatures and surface concentrations of long-lived trace gases and ozone-depleting substances. We then used the same model framework to differentiate the role of chemically active composition (ozone, methane, and chlorofluorocarbons) and CO2 changes on observed trends in the stratosphere. Among the sensitivity factors analyzed, our simulations indicate that changes in CO2 over the simulated period do not lead to significantly different total ozone trend; however, changes in CO2 lead to important differences in ozone in the upper part of the model. On the other hand, changes in surface methane concentration are shown to play a significant role in driving changes in the globally averaged total ozone column, through a combination of changes in tropospheric and stratospheric ozone columns. We also show that the correlation between a change in tropical mean age of air and in vertical velocity breaks down above 20 hPa, in association with increased isentropic mixing above that level. Finally, we show that our model is capable of reproducing trends in the tropical age of air that were found in other studies; our simulations also indicate a significant impact of keeping methane and ozone-depleting substances at their 1970 levels, indicating the potentially important role of controlling methane emissions.