Robust Acceleration of Stratospheric Moistening and Its Radiative Feedback Under Greenhouse Warming
Robust Acceleration of Stratospheric Moistening and Its Radiative Feedback Under Greenhouse Warming
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DOI：
10.1029/2020jd033090
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
Y. Xia;Yi Huang;Yongyun Hu
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文献类型：
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作者：
Y. Xia;Yi Huang;Yongyun Hu
平流层水汽（SWV）的变化，响应于增加的CO2，作为一个反馈组件可能在地球的能量收支中发挥重要作用。在过去的十年里，它引起了广泛的研究。在这里，我们使用CMIP 6模式集合中的150年CO2强迫（1 pctCO 2）模拟来计算SWV气候反馈。所有模型都有力地显示了平流层的湿润，导致了对地表变暖的正辐射反馈。我们发现平流层增湿率和SWV反馈都随着地面变暖而增加。在前50个模型年中，增湿的速率为0.9 ± 0.1 ppmv K−1，用固定动力加热法测得的增湿辐射反馈为0.11 ± 0.02 W m−2 K−1;在过去50个模型年中，增湿率增加到1.2 ± 0.2 ppmv K−1，反馈增加到0.16 ± 0.03 W m−2 K−1，地表温度高出3.3K。这些增加被发现是由热带对流层顶变暖相对于地面变暖的放大率引起的，这两个50年的周期分别为0.6和1.1 K K−1。我们的结论是，SWV反馈加强与地面变暖，这可能有助于增加气候敏感性，在未来的全球变暖。
Stratospheric water vapor (SWV) changes, in response to increasing CO2, as a feedback component may play an important role in the Earth's energy budget. It has drawn extensive studies in the past decade. Here, we calculate the SWV climate feedback using the 150‐year CO2 forcing (1pctCO2) simulations in the CMIP6 ensemble of models. All models robustly show a moistening of the stratosphere, causing a positive radiative feedback to surface warming. We find that the stratospheric moistening rate and the SWV feedback both increase with surface warming. The moistening occurs at a rate of 0.9 ± 0.1 ppmv K−1 and its radiative feedback measured by the fixed dynamical heating method is 0.11 ± 0.02 W m−2 K−1 in the first 50 model years; the moistening rate increases to 1.2 ± 0.2 ppmv K−1 and the feedback increases to 0.16 ± 0.03 W m−2 K−1 in the last 50 model years when the global‐mean surface temperature is 3.3 K warmer. These increases are found to be caused by an amplified rate of tropical tropopause warming with respect to surface warming, which is 0.6 and 1.1 K K−1 for the two 50‐year periods, respectively. We conclude that the SWV feedback is strengthening with surface warming, which can contribute to increasing climate sensitivity in the future under global warming.