Equilibrium Climate Sensitivity Obtained From Multimillennial Runs of Two GFDL Climate Models
Equilibrium Climate Sensitivity Obtained From Multimillennial Runs of Two GFDL Climate Models
复制标题
从两个 GFDL 气候模型的千年运行中获得的平衡气候敏感性
DOI：
10.1002/2017jd027885
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Levi G. Silvers
中科院分区：
文献类型：
--
作者：
D. Paynter;T. Frölicher;L. Horowitz;Levi G. Silvers
平衡气候敏感性（ECS），定义为响应于大气CO2加倍的全球平均地表气温的长期变化，通常是通过混合层海洋的短期大气模拟计算出来的，或者使用短期调整期间的线性回归推断出来的。我们报告了两个地球物理流体动力学实验室（GFDL）环流模式（GCMs）， ESM2M和CM3分别为3.3 K和4.8 K的千年模拟的实际ECS。这两个值都比政府间气候变化专门委员会第五次评估报告中通过回归地球能量对温度的不平衡而得出的相同模式的估价值高出1 K。这种低估主要是由于在大气CO2稳定后的第一个世纪内气候反馈参数（−α）的变化。对于这两种gcm，通过将CO2以每年1%的速度增加到两倍，并在CO2保持不变后使用51-350年，可以用线性回归估计ECS在0.3 K以内。我们发现−α的变化在两种gcm之间是不同的，并且与gcm在向平衡方向发展过程中所经历的500 hPa （ω500）垂直速度和估计反转强度的变化密切相关。这表明，虽然云物理参数化对于确定−α的强度很重要，但由于海面温度模式的变化而导致的大气状态的本质差异可能同样重要。
Equilibrium climate sensitivity (ECS), defined as the long‐term change in global mean surface air temperature in response to doubling atmospheric CO2, is usually computed from short atmospheric simulations over a mixed layer ocean, or inferred using a linear regression over a short‐time period of adjustment. We report the actual ECS from multimillenial simulations of two Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models (GCMs), ESM2M, and CM3 of 3.3 K and 4.8 K, respectively. Both values are ~1 K higher than estimates for the same models reported in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change obtained by regressing the Earth's energy imbalance against temperature. This underestimate is mainly due to changes in the climate feedback parameter (−α) within the first century after atmospheric CO2 has stabilized. For both GCMs it is possible to estimate ECS with linear regression to within 0.3 K by increasing CO2 at 1% per year to doubling and using years 51–350 after CO2 is constant. We show that changes in −α differ between the two GCMs and are strongly tied to the changes in both vertical velocity at 500 hPa (ω500) and estimated inversion strength that the GCMs experience during the progression toward the equilibrium. This suggests that while cloud physics parametrizations are important for determining the strength of −α, the substantially different atmospheric state resulting from a changed sea surface temperature pattern may be of equal importance.