过去1000年气候模拟比较和机制分析

CLIMATE OF THE PAST 1000 YEARS:SIMULATION AND MECHANISM

利用中等复杂程度模式MPM-2进行的多情景1000年气候模拟试验和全球海气耦合气候模式ECHO-G进行的1000年长时间积分气候模拟试验结果,分析了过去1000年全球气候变化特征及其与各强迫因子变化的关系,并与部分温度重建资料作了对比,探讨了近千年气候变化的原因和驱动因子。模拟和重建结果均反映出了大约出现在1000～1300年的中世纪暖期、1300～1850年的小冰期和1860年之后的全球升温期。对于1300～1850年的小冰期和1860年之后的升温期,模拟和重建的趋势基本一致,尤其是1670～1710年Maunder太阳黑子最小期时,模拟和重建结果吻合很好。各因子及其组合的强迫试验表明,在不同典型气候时期,强迫因子的作用是不一样的。1000～1300年的中世纪暖期,模拟与重建资料存在一定的位相差异和幅度差异。从整体上来看,模式得出的温度距平值要小于重建温度距平值。在1000年尺度上,太阳辐射、火山活动和温室气体对全球温度变化都有重要意义,但表现的时间不同。在最近百年尺度上,温室气体含量的变化对温度的变化起着相对更为重要的作用。

In this paper,the modeling results of the past 1000 years＇ climate changes with models MPM-2 and ECHO-G were reported, these climate changes and their relations to forcing factors are analyzed, and the cause and driving factors to result in the climate changes were discussed. Model MPM-2 is an Earth-system model with intermediate complexity,whereas model ECHO-G is a coupled global climate model. The scenarios simulated mainly involve the following forcing factors： solar radiation, volcanic dust, and CO2 concentration. The effect of solar activity and volcanic eruption on solar radiation is combined in the one index called the effective solar radiation. In order to evaluate the effect of each single factor,experiments of 1000 years in time interval were designed. The combining effect of different forcing factors on the global surface air temperature were analyzed and compared with the reconstruction results based on climate data. The simulated climate change trend by these two models is by and large in line with the reconstructed climate change. There were the following climate times in the past 1000 years： warm during 1000 - 1300, corresponding to the Medieval Warm Period （MWP）; cold during 1300- 1850, corresponding to the Little Ice Age （LIA） ; and warming since 1860. Especially for the maunder minimum of 1670 - 1710, the modeling result highly agree with the reconstruction result. The sensitive experiments show that the roles of forcing factors are varying with periods and time scales. It is found that the major difference between the simulated and the reconstructed temperature series would occur in the MWP of 1000- 1300, significantly representing in phase and amplitude. In general, the simulated temperature anomalies are less than the reconstructed temperature anomalies. At the millennium scale, solar activity, volcanic eruption, and greenhouse gas are important for the global temperature change. On the other hand, for the past 100 years,the change of greenhouse gas had more contribution to the global temperature change. It is also found that the decrease of CO2 concentration would produce about 0. 1 ℃ cooling in the LIA, accounting for one third of the temperature amplitude. The comparison of the results given by these two models shows that although they can be used to predict the climate trend,model MPM-2 seems to be more efficient and convenient than model ECHO-G in long range experiments.