利用遥感反演的叶面积指数研究中国东部生态系统对东亚季风的响应

利用遥感信息反演的叶面积指数(LAI)数据和生物气候数据,研究区域尺度的植被生态系统季节和年际变化对东亚季风的响应.结果发现,中国东部季风区的植被生态系统与东亚季风气候呈显著的年际和季节变化相关.在季节尺度上表现为随着东亚季风从春季到秋季的由南向北的推进过程,植被生态系统出现明显的季节变化;在年际尺度上,高的LAI出现于强的东亚季风年,而低的LAI值则与弱的东亚季风年相对应.证明中国东部季风区呈现出季风驱动生态系统的明显特征,而且LAI可显示这一强的信号.     

中国西部绿化对东亚季风气候影响的数值模拟

中国西部大开发战略中的生态环境建设将在西部地区引起显著的地表覆盖变化。根据最新的全球地表特征数据库资料和21世纪初中国西部生态环境三大重点建设工程的具体规划，得出两种植被，即现实植被和虚拟植被。并利用RIEMS—TEA模式，通过一次敏感性试验，发现西部地区绿化明显影响东亚的季风系统和中国东部季风区气候。模拟试验显示，中国西部绿化会明显增强东亚夏季风，这将会加强中国东部由南向北的水汽输送，并有利于输送邻近海洋的水汽到大陆，使得中国大陆东部季风区整体出现降温、增湿和降水增加。而且，温度、湿度、气压和风速受影响的程度在垂直方向上都已超出了边界层之外。     

中国藏北高寒生态遥感植被变化及成因分析

 利用NOAA/AVHRR-NDVI遥感数据研究了近20年藏北高寒生态系统植被变化趋势,发现藏北植被覆盖呈现出东部高,西部低的态势;依次是农作区和森林区>高寒草甸>高寒草原>高寒荒漠草原。空间分布显示NDVI显著增加或减少的区域分布在地势比较低的东部和中部地区的森林区和高寒草甸区,在海拔较高的西部地区的高寒荒漠草原NDVI变化趋势处于轻微变化或无变化。分析造成植被变化的气候原因（温度、降水,风）和人为原因,认为不同区域植被动态变化的主导因素不同;藏北东部地区,植被变化受人类活动因素影响比较显著;中部地区,同期气候条件有所改善,植被覆盖呈增加趋势,年平均最低温度和降水对植被生长具有正效应,而风力和辐射减少引起该区植被蒸散下降也有利于植被生长。藏北地区西部为无人区,不受人类活动太大的影响,因而藏北西北部的植被变化可能更多的表现出藏北高原植被的自然变动。     

利用卫星遥感资料对中国地表植被及荒漠化时空演变和分布的研究

利用1982～1999年NOAA-AVHRR卫星遥感数据,通过对归一化的植被指数进行自然正交分解,反演获得了我国18年来地表植被覆盖的分布及其时空变化状况,发现这一期间我国大部分地区地表植被覆盖状况明显退化,分析得出气候因素不是造成我国地表植被覆盖状况变化的主要原因,人为因素的影响更为重要.     

区域环境变化研究的重要科学问题——国家自然科学基金“21世纪核心科学问题

全球性环境问题是地球系统整体行为的结果，既涉及地球系统各圈层之间的相互作用，也与人类对地球系统的作用密切相关。区域环境变化是全球环境问题在区域上的反映和缩影，探讨区域环境变化问题既能丰富全球环境变化的研究内容，又可以为实施区域社会经济可持续发展服务。国家自然科学基金“十五”期间可以优先资助从区域的角度开展的全球变化研究，并注重研究区域变化对全球变化的影响和响应，具体研究方向：（1）海洋－大气－陆地相互作用与水循环；（2）东亚季风环境的形成演化及其对全球变化的响应与影响；（3）陆地生态系统生产力与全球变化的相互作用；（4）区域碳平衡及典型生源要素的生物地球化学过程；（5）人类活动对区域环境的影响。     

气候变化与人类活动对植被覆盖的影响

为了研究气侯变化及人类活动对区域植被覆盖变化的内在影响,采用2000—2016年MODIS NDVI数据,通过像元二分法计算获得植被覆盖度,结合气象站点监测数据,利用MannKendall突变检验、转移矩阵、残差分析等方法,探讨气候变化和人类活动影响下,陕西省2000—2016年植被覆盖度的时空变化特征。结果表明:2000—2016年陕西省年平均气温和年降雨量均总体增加。其中,2006—2008年是气候突变时期,植被覆盖度在气候突变后明显增加。陕西省平均植被覆盖度总体增加。其中,陕北地区植被覆盖度明显增加,2000—2016年增加0. 33;关中地区植被覆盖度有所下降,2000—2016年降低0. 06,以西安周边地区为主;陕南地区植被覆盖度有小幅降低,2000—2016年植被覆盖度降低0. 02.陕西省人类活动对植被覆盖度影响具有明显空间差异。其中,陕北地区人类活动影响力对植被覆盖影响力具有正向作用,促进植被覆盖度增加;关中地区人类活动影响力具有负向作用,导致植被覆盖度降低;陕南地区人类活动影响力较低,导致陕南地区植被覆盖有小幅度降低。植被覆盖对气候变化响应明显,人类活动影响力在持续增强。     

山西省植被覆盖变化及其影响因素研究

利用1982—2011年遥感与气象数据,分析了山西省植被覆盖变化的时空格局,从气候因子和人类活动两方面定量研究对植被覆盖变化的影响.结果表明,山西省植被覆盖及其年际稳定性呈现出由东南向西北递减的趋势;山西省植被覆盖年际变化空间上存在地域差异,恒山以北区域、各大小盆地植被覆盖增强,吕梁山脉与太行山脉植被覆盖减弱;气候因素对植被覆盖影响较深,温度和降水共同作用于植被覆盖,植被覆盖与温度的相关性比降水更为显著;人类活动对植被覆盖的影响不容忽视,且与海拔具有相关性,低海拔区域表现为负作用,高海拔区域表现为正作用.     

塔克拉玛干沙漠西北边缘植被特征与生态保护策略

塔克拉玛千沙漠西北地区属于暖温带干旱荒漠气候，植物区系包括中亚成分、古地中海成分等，分布着荒漠生态系统、自然绿洲生态系统和自然水域生态系统，在过境河流两岸分布着草垫带—森林带—固定沙包带—流沙带，植被类型有草甸植被、森林植被、灌木植被、沙生植被和盐生植被。水分状况是导致区域植被变化的主要因素，人类活动也在影响植物群落演替变迁。本通过实地调查．分析了区域生态系统、植被群落类型及其结构特征和植被动态演替，分析了各种植被类型的生态与生产功能。并对合理利用水资源、保护绿洲、荒漠过渡带值被、优化荒漠边缘带生态系统、促进绿洲可持续发展提出对策建议。     

培育生命之树追溯思想之源

在40多亿年的历史中,地球上的生命伴随地球的发展而进化,期间大部分时间里,生命只存在于海洋.伴随地球大陆漂移、物理环境及气候的变化,生命由海洋迁徙到陆地,逐步进化演变并出现人类.由此,人类和自然走上了一条相互冲突的道路,人类的活动对地球环境和资源造成了不可逆转的损失.正是"生命因地球变化而变化,地球也因生命的变化而改变".     

区域环境变化研究的重要科学问题--国家自然科学基金\\"21世纪核心科学问题\\"论坛

全球性环境问题是地球系统整体行为的结果,既涉及地球系统各圈层之间的相互作用,也与人类对地球系统的作用密切相关.区域环境变化是全球环境问题在区域上的反映和缩影.探讨区域环境变化问题既能丰富全球环境变化的研究内容,又可以为实施区域社会经济可持续发展服务.国家自然科学基金\\"十五\\"期间可以优先资助从区域的角度开展的全球变化研究,并注重研究区域变化对全球变化的影响和响应.具体研究方向:(1)海洋-大气-陆地相互作用与水循环;(2)东亚季风环境的形成演化及其对全球变化的响应与影响;(3)陆地生态系统生产力与全球变化的相互作用;(4)区域碳平衡及典型生源要素的生物地球化学过程;(5)人类活动对区域环境的影响.     

An virtual numerical experiment to understand the impacts of recovering natural vegetation on the summer climate and environmental conditions in East Asia

By applying a regional integrated environmental model system (RIEMS), a virtual numerical experiment is implemented to study the impacts of recovering natural vegetation on the regional climate and environmental conditions. The results show that recovering the natural vegetation in large scale could have significant influence on summer climate in East Asia. Not only would it be able to change the surface climate, but also to modify to certain extent the intensity of monsoon circulation. Although this is a virtual experiment at an extremely ideal condition, the implication of the simulating results is that the on-going nation-wide activities to recover the crop land for forest and pasture must be managed according to the local natural climate, hydrological and soil conditions. Only under such a condition, would the recovering of natural vegetation bring about significant climate and environmental benefits at regional scale.     

Influence of the Tibetan Plateau uplift on the Asian monsoon-arid environment evolution

As one of the most important geological events in Cenozoic era,the uplift of the Tibetan Plateau(TP)has had profound influences on the Asian and global climate and environment evolution.During the past four decades,many scholars from China and abroad have studied climatic and environmental effects of the TP uplift by using a variety of geological records and paleoclimate numerical simulations.The existing research results enrich our understanding of the mechanisms of Asian monsoon changes and interior aridification,but so far there are still a lot of issues that need to be thought deeply and investigated further.This paper attempts to review the research on the influence of the TP uplift on the Asian monsoon-arid environment,summarize three types of numerical simulations including bulk-plateau uplift,phased uplift and sub-regional uplift,and especially to analyze regional differences in responses of climate and environment to different forms of tectonic uplifts.From previous modeling results,the land-sea distribution and the Himalayan uplift may have a large effect in the establishment and development of the South Asian monsoon.However,the formation and evolution of the monsoon in northern East Asia,the intensified dryness north of the TP and enhanced Asian dust cycle may be more closely related to the uplift of the main body,especially the northern part of the TP.In this review,we also discuss relative roles of the TP uplift and other impact factors,origins of the South Asian monsoon and East Asian monsoon,feedback effects and nonlinear responses of climatic and environmental changes to the plateau uplift.Finally,we make comparisons between numerical simulations and geological records,discuss their uncertainties,and highlight some problems worthy of further studying.     

Southern Hemisphere mean zonal wind in upper troposphere and East Asian summer monsoon circulation

1 Introduction Variability of the East Asian summer monsoon (EASM) has been detected by considering roles of El Nino and Southern Oscillation (ENSO) cycle, snow cover over Eurasia and Tibetan Plateau, and signals from the soil (namely, the soil temperatur…     

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…     

Response of the East Asian climate system to water and heat changes of global frozen soil using NCAR CAM model

Under the condition of land-atmosphere heat and water conservation, a set of sensitive numerical experiments are set up to investigate the response of the East Asian climate system to global frozen soil change. This is done by introducing the supercooled soil water process into the Community Land Model (CLM3.0), which has been coupled to the National Center of Atmospheric Research Community Atmosphere Model (CAM3.1). Results show that:(1) The ratio between soil ice and soil water in CLM3.0 is clearly changed by the supercooled soil water process. Ground surface temperature and soil temperature are also affected. (2) The Eurasian (including East Asian) climate system is sensitive to changes of heat and water in frozen soil regions. In January, the Aleutian low sea level pressure circulation is strengthened, Ural blocking high at 500 hPa weakened, and East Asian trough weakened. In July, sea level pressure over the Aleutian Islands region is significantly reduced; there are negative anomalies of 500 hPa geopotential height over the East Asian mainland, and positive anomalies over the East Asian ocean. (3) In January, the southerly component of the 850 hPa wind field over East Asia increases, indicating a weakened winter monsoon. In July, cyclonic anomalies appear on the East Asian mainland while there are anticyclonic anomalies over the ocean, reflective of a strengthened east coast summer monsoon. (4) Summer rainfall in East Asia changed significantly, including substantial precipitation increase on the southern Qinghai-Tibet Plateau, central Yangtze River Basin, and northeast China. Summer rainfall significantly decreased in south China and Hainan Island, but slightly decreased in central and north China. Further analysis showed considerable upper air motion along ~30°N latitude, with substantial descent of air at its north and south sides. Warm and humid air from the Northeast Pacific converged with cold air from northern land areas, representing the main cause of the precipitation anomalies.     

青藏高原：全球气候变化的驱动机与放大器──Ⅲ．青藏高原隆起对气候变化的影响

新生代出现的几次重大气候变化事件与青藏高原形成过程中经历的几次强烈构造运动在发生年代上的良好对应关系表明两者存在紧密的联系．或许正是青藏高原的隆起导致了气候的巨大变化和现代东亚季风的形成及加强．高大的高原对大气系统有两个重要影响，热力作用和动力作用．它们在亚洲冬季形成蒙古高压、夏季形成印度低压，从而导致东亚季风出现．青藏高原越高，其对大气的作用越显著，形成的蒙古高压、印度低压和东亚季风越强大．因此，东亚季风的形成和加强是青藏高原隆起的结果．东亚季风的加强和高原动力作用使西风带波动增加，造成冰期极地冷空气不断南侵、气候波动变大．青藏高原抬升和季风造成的化学风化增强还使大气ＣＯ２含量降低、气候变冷．因此，青藏高原隆起是控制新生代气候变化的重要因素．     

East Asian monsoon change for the 21st century: Results of CMIP3 and CMIP5 models

Forty-two climate models participating in the Coupled Model Intercomparison Project Phases 3 and 5 were first evaluated in terms of their ability to simulate the present climatology of the East Asian winter (December-February) and summer (June-August) monsoons. The East Asian winter and summer monsoon changes over the 21st century were then projected using the results of 31 and 29 reliable climate models under the Special Report on Emissions Scenarios (SRES) mid-range A1B scenario or the Representative Concentration Pathways (RCP) mid-low-range RCP4.5 scenario, respectively. Results showed that the East Asian winter monsoon changes little over time as a whole relative to the reference period 1980-1999. Regionally, it weakens (strengthens) north (south) of about 25°N in East Asia, which results from atmospheric circulation changes over the western North Pacific and Northeast Asia owing to the weakening and northward shift of the Aleutian Low, and from decreased north- west-southeast thermal and sea level pressure differences across Northeast Asia. In summer, monsoon strengthens slightly in East China over the 21st century as a consequence of an increased land-sea thermal contrast between the East Asian continent and the adjacent western North Pacific and South China Sea.     

Multiscale characteristics of the rainy season rainfall and interdecadal decaying of summer monsoon in North China

This paper focuses on the rainfall spectrum and its evolution of North China in rainy season with summer monsoon decaying in interdecadal time scale. The interannual component of the rainfall is the dominant part, accounting for 85% of the total variance, and has been changed significantly during the last 30 years. According to wavelet analysis its 5a periodic spectrum suddenly disappeared in the late 1960s, and its biennial oscillation gradually become weaker and weaker since 1970, accompanied by the summer monsoon decaying. Contrarily, the interdecadal component is principal in the summer monsoon over North China and is very similar to the counterpart of the rainfall. Their interdecadal parts are significantly correlated, and the correlation coefficient is nearly equal to the one of the original sequences.Besides, the dry and wet climate alternated with the monsoon abrupt changes in the 1960s and the 1970s over East Asia, apart from North China, climate drifted from a light drought to a severe drought during the past 30 years.