全新世暖期鼎盛期与未来变暖情景下东亚夏季降水和气温变化对比

利用通用气候系统模式(Community Climate System Model,简称CCSM)全新世和21世纪气候模拟试验数据,对比分析了全新世暖期鼎盛期和RCP4.5(Representative Concentration Pathway 4.5,简称RCP4.5)未来变暖情景下东亚地区夏季地表气温和降水的空间分布特征,并探讨了两个暖期夏季气候变化的成因机制。结果表明:1)全新世东亚地区最暖的夏季出现在9 ka B.P.前后,这与地球轨道参数有关;2)RCP4.5温室气体排放情景下21世纪整个东亚地区的夏季平均地表气温均呈上升趋势,而在全新世暖期鼎盛期东亚地区的夏季地表气温呈现同心圆状分布;3)全新世暖期鼎盛期和未来变暖情景下东亚地区夏季降水的空间分布有明显差异,前者东亚地区的夏季降水呈现"南负北正"的偶极子分布形态,而后者呈三极子形势;前者东亚夏季降水的变化幅度明显强于后者;4)全新世暖期鼎盛期副高偏强,中国东部偏南气流较强;而在RCP4.5未来变暖情景下副高偏弱。

Comparison of the summer surface air temperature and precipitation over East Asia between the Holocene Thermal Maximum and the RCP4.5 scenario

Based on the simulation of the Holocene from Community Climate System Model version 3(CCSM3) and the simulation of the 21st century in Representative Concentration Pathway 4.5(RCP4.5 or 2006~2100 C.E.) from Community Climate System Model version 4(CCSM4), the historical simulations from CCSM3 and CCSM4 also be used in this study. We selected the warmest 100 years through the Holocene(HW100 or 9180~9081 a B. P.) and analyzed the spatial distribution of surface air temperature and precipitation in summer(JJA) over East Asia(22.5°~45.0°N, 100°~122°E) between the HW100 and RCP4.5 by using the differential analysis, and the potential mechanism of the climatic variation has been discussed as well. The results indicate that:(1) the period around 9 ka BP has witnessed the warmest summer through the Holocene in the East Asia, which concerns the variation of Earth orbit parameters;(2) An overall rise of average summer surface temperature in the East Asia through the 21st century has been discovered under the RCP4.5 greenhouse gas emission scenario while that in the peak of the Holocene warm period has been found to be a concentric circle pattern;(3) Evident differences exist between the two above-mentioned scenarios, with the distribution of summer precipitation being a dipole pattern(negative in South and positive in North) in HW100 and a triple one under RCP4.5 scenario, and the variation of the former is much more fluctuant;(4) Strength of subtropical high has also been detected to differ:a stronger one has been found in HW100 with a powerful southerly flow throughout Eastern China while that under RCP4.5 scenario seems to be weaker.