过去两千年青藏高原百年尺度温度变化的时空格局

基于青藏高原过去2000 a高分辨率的温度代用序列, 通过区域对比以及集成分析方法, 深入分析青藏高原过去2000 a温度变化的时空特征。结果表明: 过去2000 a青藏高原温度变化可以划分为4个世纪尺度的冷暖时期, 即0—600 AD和1400—1900 AD的冷期、600—1400 AD和20世纪的暖期, 其中1400—1900 AD和600—1400 AD可能分别对应于欧洲的小冰期和中世纪暖期; 青藏高原过去2000 a温度变化存在很强的季节性特征, 年平均气温变化存在争议, 但夏季温度变化较为一致; 夏季温度记录表明20世纪升温并不是很显著, 中世纪暖期是过去2000 a中升温最显著且最温暖的时段。目前, 青藏高原过去2000 a古温度记录仍存在空白区域, 转换函数的选取、气候指标的季节性差异以及定年误差等因素都可能增加温度序列的不确定性。未来, 在青藏高原还需要重建更多高质量(高分辨率、有准确的年龄控制、明确的季节性以及精确的气候指示意义)的古温度记录, 以更深入地揭示青藏高原温度变化的时空格局及机制。     

Reconstruction of temperature series of China for the last 1000 years

This paper reports a study on reconstructing temperature series for ten regions of China over the last 1000 years with a time resolution of 10 a. The regions concerned are: Northeast, North, East, South China, Taiwan, Central, Southwest, Northwest China, Xinjiang and Qinghai-Tibet Plateau. A variety of proxy data, such as ice core, tree-rings, stalagmites, peat, lake sediments, pollen and historical records, were validated with instrumental observations made in the last 120 years, and applied in the recon- struction of the temperature series. A temperature series for whole China is then established by aver- aging the ten regional series with a weighting proportional to the area of each region. Finally, tem- perature variations for the last 1000 years are examined, with special focus placed on the characteris- tics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW).     

A comparison of the Medieval Warm Period, Little Ice Age and 20th century warming simulated by the FGOALS climate system model

To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-l...     

Simulation of the climatic effects of natural forcings during the pre-industrial era

The MPM-2,an Earth system model of intermediate complexity,is employed to study the climate sys-tem response to natural forcings during the pre-industrial era (1000-1800 AD),with a special focus on the surface air temperature (SAT) evolution. Solar radiation and volcanism are the primary natural forcings during this period. In the MPM-2,the solar radiation forcing determines the long-term trend of the climate system change,and the volcanic forcing intensifies (weakens) this trend. Ultimately,the combination of solar and volcanic forcings dominates the long-term changes of the climate system. These results are in good agreement with other model data or temperature reconstructions. Natural forcings can well explain the Little Ice Age (LIA) and the Medieval Warm Period (MWP). At the large regional scale,the SAT response to natural forcings is almost coincident with that of the Northern Hemisphere. Based on MPM-2 model results,it is concluded that the global climate gradually became cold during the pre-industrial era. However,MPM-2 model results substantially correlate with recon-structed solar and volcanic forcings. Namely,to some great extent,these results strongly rely on the forcing series data we choose. Therefore,in order to accurately simulate the secular variation of the historical climate,it is very important to reconstruct well the solar radiation change and volcanic forc-ing data are well reconstructed for the past 10000 years,at least for the past 2000 years,in addition to the model improvements. The sensitivity study on the abrupt solar radiation change indicates that the increased solar radiation not only strengthens the nonlinear response of SAT,but intensifies the global hydrological cycle. At the same time,the biosphere is also affected obviously.     

Characteristics of decadal-centennial-scale changes in East Asian summer monsoon circulation and precipitation during the Medieval Warm Period and Little Ice Age and in the present day

Using meteorological observations, proxies of precipitation and temperature, and climate simulation outputs, we synthetically analyzed the regularities of decadal-centennial-scale changes in the summer thermal contrast between land and ocean and summer precipitation over the East Asian monsoon region during the past millennium; compared the basic characteristics of the East Asian summer monsoon (EASM) circulation and precipitation in the present day, the Little Ice Age (LIA) and the Medieval Warm Period (MWP); and explored their links with solar irradiance and global climate change. The results indicate that over the last 150 years, the EASM circulation and precipitation, indicated by the temperature contrast between the East Asian mainland and adjacent oceans, had a significant decadal perturbation and have been weaker during the period of rapid global warming over the past 50 years. On the centennial time scale, the EASM in the MWP was strongest over the past 1000 years. Over the past 1000 years, the EASM was weakest in 1450-1570. When the EASM circulation was weaker, the monsoon rain belt over eastern China was generally located more southward, with there being less precipitation in North China and more precipitation in the Yangtze River valley; therefore, there was an anomalous pattern of southern flood/northern drought. From the 1900s to 1920s, precipitation had a pat- tern opposite to that of the southern flood/northern drought, with there being less precipitation in the Yangtze River valley and more precipitation in North China. Compared with the case for the MWP, there was a longer-time-scale southern flood/northern drought phenomenon in 1400-1600. Moreover, the EASM circulation and precipitation did not synchronously vary with the trend of global temperature. During the last 150 years, although the annual mean surface temperature around the world and in China has increased, the EASM circulation and precipitation did not have strengthening or weakening trends. Over the past 1000 years, the weakest EASM occurred ahead of the lowest Northern Hemispheric temperature and corresponded to the weakest solar irradiance.     

中国中世纪暖期温度的时空变化特征

采用全球海气耦合模式ECHO-G的1000个模式年的长积分气候模拟方法分析了中国中世纪暖期温度的存在性与时空变化特征.结果表明：中国的中世纪暖期出现在公元1000—1250年间,但它不是一个持续稳定的暖期,而是存在峰谷起伏变化,其中最暖的30年（中世纪暖期鼎盛期）出现在1131—1160年.中世纪暖期中国的年平均和冬、夏季平均温度距平变幅西部最大,东部最小.其鼎盛期中国的温度距平相对于千年温度都是正值,中国东部的增温幅度由南向北逐渐加大,变幅为0.4℃—0.8℃,而中国西部的增温呈Ω型分布,且随着海拔高度的增加,增温幅度逐渐加大,最大增温达2.0℃—2.2℃.     

明清时期中国大陆的气候变化

在我国不同地区通过不同的代用资料恢复的小冰期气候的基础上,分析总结了小冰期我国气候演化的区域分异特征.小冰期气候对中国社会的影响主要表现在：自然灾害加剧对农牧业生产造成危害,加速中国历史时期的人口迁移,对政权变更和政治疆域产生一定的影响.     

中国小冰期区域气候演化研究

在我国不同地区通过不同代用资料如冰芯、树轮、孢粉、湖泊沉积物、历史文献记录等恢复的小冰期气候的基础上, 分析总结了小冰期我国气候演化的区域分异特征,并探讨其原因机制,力图为未来气候变化提供参考。     

Humid medieval warm period recorded by magnetic characteristics of sediments from Gonghai Lake,Shanxi, North China

Variations in monsoon strength, moisture or precipitation in eastern China during the MWP reflected by different climatic records have shown apparent discrepancies. Here, detailed environmental magnetic investigations and mineralogical analyses were conducted on lacustrine sediments of Core GH09B1 (2.8 m long) from Gonghai Lake, Shanxi, North China, concerning the monsoon history during the MWP. The results demonstrate that the main magnetic mineral is magnetite. The sediments with relatively high magnetic mineral concentrations were characterized by relatively fine magnetic grain sizes, which were formed in a period of relatively strong pedogenesis and high precipitation. In contrast, the sediments with low magnetic mineral concentrations reflected an opposite process. The variations of magnetic parameters in Gonghai Lake sediments were mainly controlled by the degree of pedogenesis in the lake drainage basin, which further indicated the strength of the Asian summer monsoon. The variations in the and S 300 parameters of the core clearly reveal the Asian summer monsoon history over the last 1200 years in the study area, suggesting generally abundant precipitation and a strong summer monsoon during the Medieval Warm Period (MWP, AD 910–1220), which is supported by pollen evidence. Furthermore, this 3–6-year resolution environmental magnetic record indicates a dry event around AD 980–1050, interrupting the generally humid MWP. The summer monsoon evolution over the last millennium recorded by magnetic parameters in sediments from Gonghai Lake correlates well with historical documentation (North China) and speleothem oxygen isotopes (Wanxiang Cave), as well as precipitation modeling results (extratropical East Asia), which all indicate a generally humid MWP within which centennial-scale moisture variability existed. It is thus demonstrated that environmental magnetic parameters could be used as an effective proxy for monsoon climate variations in high-resolution lacustrine sediments.     

中国东部季风区小冰期干湿变化及影响机制

通过对已发表的中国东部季风区小冰期气候重建结果和全球不同气候模式的对比分析,探讨我国季风区小冰期的气候干湿响应模式.本文认为:中国季风区小冰期的干湿变化受到西伯利亚冷高压的影响,华北和东北受影响最大,而中部和南部季风区变化机制更为复杂;我国季风区的小冰期存在以秦岭淮河(约34°N)为大致分界的北部冷干和南部冷湿模式,这种模式在千年或更长的时间尺度上的存在性,需要更多高分辨率的古气候资料以及模拟数据进行探讨.     

Palaeoclimate simulation of Little Ice Age

Promotedbytheinternationalresearch projectsofPAGESandCLIVAR ,thestudiesonclimaticandenvironmentalchangesinthepast 2 0 0 0yearshavedrawntheattentionofgeologistsandpalaeoclimato logistsallovertheworld[1,2 ] .AmongthemthecoldeventoftheLittleIceAge (LIA)isparticularlythemostattractiveone[3～ 10 ] ,whichisthenearesttypicalcoldperiodintheglobalrangefrommodernage ,andhadaprofoundimpactuponhumansociety[11] .Addi tionally ,moreknowledgeaboutthecauseoforiginanddynamicmechanismofLIAmayenrichandpe…     

15～19 世纪末期间广东的气候与灾害特征的初步探讨

从对广东有关史料记载等资料的整理分析人手,选取史料中1480—1940年间共460年的自然灾害记载,分别采用寒、暖年数统计法和湿润指数法建立不同的指标序列分析,认为,广东的小冰期开始于1480’s,结束于1890’s,其间有3次较为明显的冷期,分别出现于1480’s—1540’s,1610’s—1780’s。1830’s—1890’s,相邻冷期间为暖期,在不同的冷暖时期水热配置模式也不相同．在小冰期的不同时期具有不同的自然灾害特征,冷期内发生的灾害次数远多于暖期中发生的灾害次数．还收集整理了历史时期发生的厄尔尼诺、拉尼娜事件,并对其与广东气候及灾害特征的关系进行了初步的探讨。发现厄尔尼诺、拉尼娜事件的发生对广东各种自然灾害的发生影响不大,几者之间关系并不显著;拉尼娜事件对广东冬季气温则具有较大影响。     

Simulated and reconstructed winter temperature in the eastern China during the last millennium

Since the 1990s, under the auspicious impetus of two international research programs, the “Past Global Changes” (PAGES) and the “Climate Variability and Pre- dictability” (CLIVAR), massive research work has been carried out on climate and environment changes over the past 2000 years[1-3]. But majority of the studies has been centered on obtaining various kinds of climatic proxy data (such as historical documents, tree rings, ice cores, lake cores) and focused on the reconstruction of…