Physical constraints for temperature biases in climate models
Physical constraints for temperature biases in climate models
复制标题
气候模型中温度偏差的物理约束
DOI：
10.1002/grl.50737
复制
发表时间：
2013
影响因子：
5.2
通讯作者：
C. Schär
中科院分区：
文献类型：
--
作者：
O. Bellprat;S. Kotlarski;D. Lüthi;C. Schär
一般来说，气候模式的偏差取决于气候状态（即，不稳定）。最近的研究表明，采用稳定的温度偏差可能会导致高估南欧夏季变暖的预测。还提出了使用随温度线性增加的偏置校正。虽然这种假设对于短期预测是合理的，但人们想知道这种关系是否以及在什么温度下会趋于稳定。在这里，我们使用ENSEMBLES项目的区域气候模式模拟和单模式扰动物理系综，表明线性偏差假设在高模式温度下破裂，然后过渡到常数偏差关系。这种转变在强偏差模型模拟中很明显，并使用伪现实方法得到支持。我们表明，土壤水分稀缺解释了很大程度上的夏季温度偏差在这两个合奏和土壤水分枯竭的限制是负责的过渡。因此，线性温度偏差修正可能会过度修正夏季变暖，并隐含地假设土壤水分和温度之间的非物理关系，特别是在考虑高排放情景时。我们的结论是，一个物理上一致的和时间依赖的温度偏差校正考虑到土壤的状态将增加偏差校正的鲁棒性，并减少21世纪世纪夏季变暖的不确定性。
In general, biases of climate models depend upon the climate state (i.e., are nonstationary). Recent studies have shown that the adoption of a stationary temperature bias can lead to an overestimation of projected summer warming in southern Europe. It has also been proposed to use a bias correction that increases linearly with temperature. While such an assumption is well‐justified for near‐term projections, one wonders whether and at what temperature this relation levels off if it does. Here we show, using regional climate model simulations of the ENSEMBLES project and from a single‐model perturbed physics ensemble, that the linear bias assumption breaks down at high model temperatures, followed by a transition to a constant bias relation. This transition is apparent in strongly biased model simulations and supported using a pseudo‐reality approach. We show that soil moisture scarcity explains a large degree of summer temperature biases across both ensembles and that the limits of soil moisture depletion are responsible for the transition. A linear temperature bias correction therefore potentially over‐corrects summer warming, and implicitly assumes unphysical relations between soil moisture and temperature, in particular when considering high‐emission scenarios. We conclude that a physically consistent and time‐dependent temperature bias correction considering the state of the soil would increase the robustness of bias correction and reduce the uncertainty of 21st century summer warming.