Chemistry-Climate Model Simulations of Twenty-First Century Stratospheric Climate and Circulation Changes
Chemistry-Climate Model Simulations of Twenty-First Century Stratospheric Climate and Circulation Changes
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DOI：
10.1175/2010jcli3404.1
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发表时间：
2010-10-01
影响因子：
4.9
通讯作者：
Tian, W.
中科院分区：
文献类型：
--
作者：
Butchart, Neal;Cionni, I.;Tian, W.
在11个化学气候模式的模拟中，使用几乎相同的强迫和实验装置，分析了21世纪平流层气候和环流对温室气体（GHGs）和臭氧恢复量增加的响应。除了模拟中平流层的总体全球冷却（10 hPa时0.59 +/-6 0.07 K decade（-1））外，臭氧恢复还导致夏季南半球极地平流层下部变暖，上方冷却增强。升温速率与模式预测的臭氧恢复速率相关，从世纪上半叶到下半叶，随着恢复速率的下降，100百帕的平均温度在0.8至0.48 K十年（-1）之间变化。在冬季，北方极地平流层下部的温室气体含量不断增加，辐射冷却增加，在大多数模式中，由更强的极地下降流的绝热变暖平衡。在南极低平流层，模型模拟了极地平流层云形成所需的极端低温增加，但在所有模型中，这种积极趋势在21世纪都在减少。在北极，没有一个模型模拟了整个世纪北极PSC在统计上的显著增加。亚热带急流加速响应气候变化，臭氧恢复在夏季期间使南极上空平流层下部的风向西加速，尽管这种响应对模型预测的恢复速度很敏感。在平流层的整个深度，Brewer-Dobson环流都在加强，在具有这种诊断的模式中，几乎所有地方的空气平均年龄都以大约0.05年十年（-1）的速度减少。平均而言，平流层低层（类似于70 hPa）的年平均热带上升流增加了近2%的十年（-1），其中59%的趋势是由模型中参数化的地形重力波阻力造成的。这是副热带急流向东加速的结果，它增加了到达这些纬度平流层低层的（参数化）动量的向上通量。
The response of stratospheric climate and circulation to increasing amounts of greenhouse gases (GHGs) and ozone recovery in the twenty-first century is analyzed in simulations of 11 chemistry-climate models using near-identical forcings and experimental setup. In addition to an overall global cooling of the stratosphere in the simulations (0.59 +/- 6 0.07 K decade(-1) at 10 hPa), ozone recovery causes a warming of the Southern Hemisphere polar lower stratosphere in summer with enhanced cooling above. The rate of warming correlates with the rate of ozone recovery projected by the models and, on average, changes from 0.8 to 0.48 K decade(-1) at 100 hPa as the rate of recovery declines from the first to the second half of the century. In the winter northern polar lower stratosphere the increased radiative cooling from the growing abundance of GHGs is, in most models, balanced by adiabatic warming from stronger polar downwelling. In the Antarctic lower stratosphere the models simulate an increase in low temperature extremes required for polar stratospheric cloud (PSC) formation, but the positive trend is decreasing over the twenty-first century in all models. In the Arctic, none of the models simulates a statistically significant increase in Arctic PSCs throughout the twenty-first century. The subtropical jets accelerate in response to climate change and the ozone recovery produces a westward acceleration of the lower-stratospheric wind over the Antarctic during summer, though this response is sensitive to the rate of recovery projected by the models. There is a strengthening of the Brewer-Dobson circulation throughout the depth of the stratosphere, which reduces the mean age of air nearly everywhere at a rate of about 0.05 yr decade(-1) in those models with this diagnostic. On average, the annual mean tropical upwelling in the lower stratosphere (similar to 70 hPa) increases by almost 2% decade(-1), with 59% of this trend forced by the parameterized orographic gravity wave drag in the models. This is a consequence of the eastward acceleration of the subtropical jets, which increases the upward flux of (parameterized) momentum reaching the lower stratosphere in these latitudes.