The CSIRO Mk3L climate system model version 1.0 - Part 2: Response to external forcings
The CSIRO Mk3L climate system model version 1.0 - Part 2: Response to external forcings
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DOI：
10.5194/gmd-5-649-2012
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发表时间：
2011-12
影响因子：
5.1
通讯作者：
S. Phipps;L. Rotstayn;H. Gordon;J. Roberts;A. Hirst;W. Budd
中科院分区：
文献类型：
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作者：
S. Phipps;L. Rotstayn;H. Gordon;J. Roberts;A. Hirst;W. Budd
抽象的。CSIRO Mk3L气候系统模式是一个耦合的大气环流模式，主要用于千年尺度的气候模拟和古气候研究。MK3L包括描述大气、海洋、海冰和陆地表面的组件，并将计算效率与稳定和现实的控制气候学相结合。研究界可以免费获得这本书。本文评估了模式对与气候系统过去和未来变化相对应的外部强迫的响应。对全新世中期的气候进行了模拟，其中施加了入射太阳辐射的季节和经向分布的变化。Mk3L正确地模拟了中纬度北部夏季气温上升和热带地区降温。然而，由于北非的降水量不足，它无法捕捉到中全新世气候的一些区域尺度特征。该模式模拟了厄尔尼诺-南方涛动的幅度减少了7%到15%，比古气候记录所暗示的减少幅度要小。然而，模式的空间分辨率相对较低，限制了模拟ENSO的真实性。然后进行了全新世晚期气候的瞬变模拟。施加了日照强度的演变分布，并应用和评估了加速技术。模式成功地捕捉到了各半球的温度变化和ENSO变率的上升趋势。然而，由于缺乏动态的植被计划，它无法模拟撒哈拉沙漠的突然沙漠化。为了评估Mk3L对其他强迫的响应，进行了上一个千年的瞬变模拟。模型应用了太阳辐射、大气温室气体浓度和火山排放的变化。该模型在模拟气候系统中更大范围的变化方面再次获得了广泛的成功。模拟的20世纪变暖的幅度和空间格局都与观测一致。然而，该模型低估了与中世纪气候异常相关的相对温暖的程度。最后，进行了三个暂态模拟，其中大气中的二氧化碳浓度分别稳定在工业化前的2倍、3倍和4倍。所有三个模拟都表明，表面持续变暖，海冰覆盖减少，北大西洋深水形成的速度减缓，随后逐渐恢复。南极底层水的形成停止了，二氧化碳浓度增加了三倍和四倍，将永久关闭。确定了模型的瞬时气候敏感性和平衡气候敏感性。CO2浓度以每年1%的速度倍增的短期瞬时响应为增温1.59±0.08K，而长期平衡响应至少为3.85±0.02K。
Abstract. The CSIRO Mk3L climate system model is a coupled general circulation model, designed primarily for millennial-scale climate simulation and palaeoclimate research. Mk3L includes components which describe the atmosphere, ocean, sea ice and land surface, and combines computational efficiency with a stable and realistic control climatology. It is freely available to the research community. This paper evaluates the response of the model to external forcings which correspond to past and future changes in the climate system. A simulation of the mid-Holocene climate is performed, in which changes in the seasonal and meridional distribution of incoming solar radiation are imposed. Mk3L correctly simulates increased summer temperatures at northern mid-latitudes and cooling in the tropics. However, it is unable to capture some of the regional-scale features of the mid-Holocene climate, with the precipitation over Northern Africa being deficient. The model simulates a reduction of between 7 and 15% in the amplitude of El Nino-Southern Oscillation, a smaller decrease than that implied by the palaeoclimate record. However, the realism of the simulated ENSO is limited by the model's relatively coarse spatial resolution. Transient simulations of the late Holocene climate are then performed. The evolving distribution of insolation is imposed, and an acceleration technique is applied and assessed. The model successfully captures the temperature changes in each hemisphere and the upward trend in ENSO variability. However, the lack of a dynamic vegetation scheme does not allow it to simulate an abrupt desertification of the Sahara. To assess the response of Mk3L to other forcings, transient simulations of the last millennium are performed. Changes in solar irradiance, atmospheric greenhouse gas concentrations and volcanic emissions are applied to the model. The model is again broadly successful at simulating larger-scale changes in the climate system. Both the magnitude and the spatial pattern of the simulated 20th century warming are consistent with observations. However, the model underestimates the magnitude of the relative warmth associated with the Mediaeval Climate Anomaly. Finally, three transient simulations are performed, in which the atmospheric CO2 concentration is stabilised at two, three and four times the pre-industrial value. All three simulations exhibit ongoing surface warming, reduced sea ice cover, and a reduction in the rate of North Atlantic Deep Water formation followed by its gradual recovery. Antarctic Bottom Water formation ceases, with the shutdown being permanent for a trebling and quadrupling of the CO2 concentration. The transient and equilibrium climate sensitivities of the model are determined. The short-term transient response to a doubling of the CO2 concentration at 1% per year is a warming of 1.59 ± 0.08 K, while the long-term equilibrium response is a warming of at least 3.85 ± 0.02 K.