Differences in Radiative Forcing, Not Sensitivity, Explain Differences in Summertime Land Temperature Variance Change Between CMIP5 and CMIP6
Differences in Radiative Forcing, Not Sensitivity, Explain Differences in Summertime Land Temperature Variance Change Between CMIP5 and CMIP6
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辐射强迫的差异（而非敏感性）解释了 CMIP5 和 CMIP6 之间夏季陆地温度变化的差异
DOI：
10.1029/2021ef002402
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Huybers, Peter
中科院分区：
文献类型：
--
作者：
Chan, Duo;Rigden, Angela;Proctor, Jonathan;Chan, Pak Wah;Huybers, Peter
夏季温度变率如何随着变暖而变化对气候适应和减缓具有重要意义。CMIP 5模拟表明，西欧极端高温的复合风险来自变暖和温度变化的增加。然而，CMIP 6模拟表明，温度变化只有适度的增加，不与变暖协变。为了探索CMIP结果的代际差异，我们将月温度方差的变化分解为对强迫敏感性的变化和强迫方差的变化。在所有模型中，CMIP 5和CMIP 6的敏感性随着局部变暖而增加，平均速率为5.7（[3.7，7.9]; 95% c.i.） × 10−3°C/W m− 2/°C升温。我们使用一个简单的湿表面能量学模型来解释由于更大的大气需求（约70%）和更干燥的土壤（约40%）而导致的敏感性增加，这部分被普朗克反馈（约10%）所抵消。相反，强迫方差在CMIP 5中是稳定的，但在CMIP 6中随着变暖而减少，平均速率为-21（[-28，-15]; 95% c.i.）W2 m − 4每°C升温。我们研究了尺度关系与平均云分数，发现平均强迫方差减少云分数的两倍CMIP 6比CMIP 5的速度。因此，CMIP 6温度变化的稳定性是敏感性和强迫变化抵消变化的结果。进一步的工作，以确定哪些模式和几代CMIP模拟更好地代表云辐射强迫的变化是重要的，评估与温度变化增加的风险。
How summertime temperature variability will change with warming has important implications for climate adaptation and mitigation. CMIP5 simulations indicate a compound risk of extreme hot temperatures in western Europe from both warming and increasing temperature variance. CMIP6 simulations, however, indicate only a moderate increase in temperature variance that does not covary with warming. To explore this intergenerational discrepancy in CMIP results, we decompose changes in monthly temperature variance into those arising from changes in sensitivity to forcing and changes in forcing variance. Across models, sensitivity increases with local warming in both CMIP5 and CMIP6 at an average rate of 5.7 ([3.7, 7.9]; 95% c.i.) × 10−3°C per W m−2per °C warming. We use a simple model of moist surface energetics to explain increased sensitivity as a consequence of greater atmospheric demand (∼70%) and drier soil (∼40%) that is partially offset by the Planck feedback (∼−10%). Conversely, forcing variance is stable in CMIP5 but decreases with warming in CMIP6 at an average rate of −21 ([−28, −15]; 95% c.i.) W2m−4per °C warming. We examine scaling relationships with mean cloud fraction and find that mean forcing variance decreases with decreasing cloud fraction at twice the rate in CMIP6 than CMIP5. The stability of CMIP6 temperature variance is, thus, a consequence of offsetting changes in sensitivity and forcing variance. Further work to determine which models and generations of CMIP simulations better represent changes in cloud radiative forcing is important for assessing risks associated with increased temperature variance.
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影响因子：
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作者：
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DOI：
10.1029/2019jd031203
发表时间：
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期刊：
Journal of Geophysical Research: Atmospheres
影响因子：
--
作者：
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通讯作者：
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