湖泊沉积物记录的过去两千年青藏高原南部干湿变化及其驱动机制

基于青藏高原南部过去2000a高分辨率的降水/湿度重建序列,通过区域对比以及集成分析方法,探讨了青藏高原南部过去2000a气候干湿变化的时空特征,并对典型时段中世纪暖期(AD 600-1400年)和小冰期(AD 1400-1900年)高原南部气候变化的特征和机制进行了着重探讨.结果显示:整体而言,过去2000a青藏高原南部气候变化显著,表现出AD 1-600年由湿转干、AD 600-1400年干旱以及AD 1400年后湿润的特征;对比分析表明,青藏高原南部在中世纪暖期和小冰期"暖干"/"冷湿"的特征,与高原东南部以及西北部地区相似,而与高原东部地区相反;过去2000a青藏高原南部气候干湿变化可能与印度季风和西风强度变化、西风在青藏高原上的季节性移动以及蒸散发强度变化有关.     

湖北省历史干湿气候的世纪振动及其比较

采用干湿指数方法对近２０００年来湖北干湿气候变化进行了分析，结果发一本地区的气候湿润状况波动明显，气候的相对干燥与湿润大致以２个世纪为周期反复交替出现，近代尽管水旱灾害频繁，但仍属于近２０００年来气候演变过程中的正常振动，气候的干湿状况总体上维持在一个比较正常的水平上。湖北气候干湿变化与我国海河流域的干湿变化具有较好的一致性。     

大兴安岭北部阿里河樟子松年轮气候响应及冬季降水重建

对大兴安岭阿里河地区樟子松(Pinus sylvestris var.mongolica)树轮年表与气候要素的响应关系进行了分析研究.结果表明:年轮指数与该地区前一年12月至当年1月平均降水存在显著的正相关关系.基于树轮宽度重建了阿里河1809年以来前一年12月至当年1月平均降水量回归方程,该方程解释了47%的冬季降水变化,且该序列与黑龙江省干湿变化存在较好的一致性.对重建序列的分析表明,该地区冬季降水变化存在4个偏干阶段和4个偏湿阶段.阿里河地区过去200a冬季降水存在干湿交替时期,即19世纪初期较干旱,中期较湿润,后期至20世纪初期较干旱,而20世纪中期较湿润,后期则相对偏干.同时,阿里河地区冬季降水存在85~38,5.0~4.5和2.2a显著的变化周期.     

福建仙山盆地泥炭沉积色度及其环境意义

以福建仙山泥炭沉积物色度为例,分析其与有机碳(TOC)含量的关系,进一步探究泥炭沉积环境的演化历史及原因.结果显示,研究区气候演化大致分3个阶段:岩芯358~280 cm(AD 600~910年),L*较低,TOC含量较高,说明植物有机体供应充分,揭示气候相对较干;岩芯280~40 cm(AD 910~1640年),L*总体偏高,TOC含量总体偏低,说明此阶段气候总体偏湿润,期间存在干湿波动;岩芯40~0 cm(AD 1640年至今),L*迅速转低,TOC含量偏高,表明气候较干燥.仙山泥炭沉积揭示的古气候变化特征是区域环境对中世纪暖期、小冰期和现代暖期等典型气候时段的区域响应,泥炭色度L*值参数与气候变化的一致性为利用L*探究区域沉积环境的变化提供了重要参考.     

广州地区晚第四纪孢粉气候研究

 利用广州地区南北2个不同沉积地貌区的钻孔进行孢粉分析,结合测年和沉积信息,分析了广州所代表的珠江三角洲地区晚更新世以来的沉积环境和气候变化。孢粉分析结果显示：在晚更新世珠江三角洲地区气候经历了偏冷干-偏凉干-暖湿-热湿-偏凉干-冷干的变化过程,末次冰期对本区具有明显影响,使全新世和晚更新世孢粉组合表现出一定的差异;全新世气候明显转暖湿,整体上以暖湿为主,但出现了一些小的气候波动事件,最明显的是在2 250 a BP 前后偏凉干的变化;该区在晚更新世和全新世各经历过一次海侵,两孔反映的气候期和海平面变化较为一致,气候和海平面变化也有很好的对应。两孔在地层、沉积相和孢粉特征上的差异是地理位置、沉积环境和基座地貌等差异造成的。     

利用湿润指数分析开封市1981—2010年干旱湿润特征

利用湿润指数对开封市1981—2010年连续30年的气候资料进行分析,开封市这30年的气候以半干旱为主,湿润指数围绕0.50这一干湿分界指标呈现明显上下波动的趋势.一年当中只有7月和8月两个月份属于湿润期,而从10月到次年6月基本为干旱期,冬、春、秋三季属于半干旱气候,只有夏季属于湿润期,水分收入主要集中在夏季.     

福建省干湿气候区划

按不同的年干燥度将全省在地域上分成半湿润、湿润和过湿润三个区。根据月干燥度的变化,分析了全省各月的干湿变化情况。最后用季干燥度将全省分成全年湿润、夏干、秋干、夏秋干、秋冬干和夏秋冬干六种气候类型。     

山东半岛小海潟湖沉积地球化学特征与环境演变

在分析小海潟湖沉积物的粘土矿物组合特征、化学元素含量变化规律以及pH值、有机质含量等一系列指标的基础上,总结出山东半岛东北部沿岸6000a以来的气候、海平面变化曲线,概括出这一区域6000a以来的环境演变大致经历了:6000～3400a BP气候温暖湿润,相对海平面较高时期;3400～1600a BP气候趋向干凉,海平面相对较低的过渡时期;1600aBP以来气候温湿,海平面有上升趋势的时期.     

近六十年全球旱地温度和降水的变化特征

旱区是全球陆地的特殊组成部分,其生态环境极为脆弱且生态的自我调节和恢复能较差,对全球变暖的响应十分敏感,是气候变化研究领域中不可忽略的重要部分。因此,研究全球旱地温度和降水变化有着重要意义。本文基于1948—2008年的CPC温度和降水资料,以及GLDAS的湿度、辐射和风速资料,结合曲线拟合、Mann-Kendall检验和小波分析等方法分析了全球旱地的温度和降水的分布及变化趋势。结果表明,全球范围内,总的增温范围比降温范围大,说明全球整体变化趋势是增暖的,且半干旱和湿润偏干区对温度的变化响应较极端干旱和干旱区更为显著。四种旱地类型的温度变化均不存在显著突变,而半干旱区和湿润偏干区降水量的负值突变更加显著;极端干旱区和干旱区的降水突变发生在60年代中期前后,而半干旱区和湿润偏干区的降水突变发生在80年代初期。不同旱地类型的温度变化周期和降水变化周期存在差异,四种旱地类型的温度变化都存在30年和20年的周期,但湿润偏干区的20周期较弱;极端干旱和干旱区的降水量的变化周期为30年,另外两种周期较短。     

过去2000 a中国东部干湿分异的百年际变化

分析了101～1900AD间中国东部每200a的干湿分异及其变化状况,讨论了它们与冷暖变化的对应关系.结果显示:2～11世纪,我国东部干湿分异为东西分异,西(西北)干东(东南)湿;12～15世纪,东西分异与南北分异并存,但仍以东西分异为主;而16～19世纪则为南北分异,北干南湿.冷暖变化与区域干湿变化的对应关系是:在暖的时期,干湿分界线偏西,最西达大同-太原-西安-汉中一线;在相对较冷的时期,干湿分界线摆向东南,达济南-菏泽-南阳一线,摆动最大幅度达5个经度以上;而在最冷的两个时段,东西分界线被南北分界线所取代.冷的时期,华北地区偏干,长江中下游及其以南地区偏湿;暖的时期,华北地区湿润,华东地区,特别是长江下游及其以南地区偏干.     

天山北麓500年来环境演变及其对人类活动的影响

文章在分析前人研究成果的基础上,总结归纳出天山北麓500年来温度、湿度以及温湿组合演变的基本规律,500年来天山北麓地区的环境演变大致经历了三个冷暖期以及四个湿润期和三个干旱期的交替,主要以冷湿、暖干的气候类型交替出现.在此基础上,笔者探讨了气候变化对干旱地区绿洲生态系统的稳定、灌溉农业的发展,水资源和环境以及灾害及其防治等方面的影响,认为气候变化有利于该地区水资源的利用,但也给部分地区带来了比较严重的洪涝灾害.     

新疆巴里坤湖全新世湖泊沉积物稳定氮同位素的气候与环境意义研究

选择位于西风环流显著影响的新疆巴里坤湖作为研究对象,结合对位于湖心部位的人工开挖剖面的多指标包括有机碳同位素（δ13C）、有机质含量（OM）和碳氮比（C/N）的对比分析和验证,发现该湖泊沉积物的δ15N记录较好地响应了过去9400年以来气候环境的变化,依据其波动变化特征,可以划分出以下阶段:9 400~7 300 cal. a BP期间,δ15N值偏低且剧烈波动,暗示了气候状况较为干旱且不稳定;7 300~5 900 cal. a BP期间,δ15N值偏高,指示气候相对湿润;5 900~3 100 cal. a BP期间,δ15N由相对高值降为低值,指示气候环境由湿转干;3 100~1 100 cal. a BP期间,δ15N总体呈现相对高值,但后期呈下降趋势,指示了此阶段中气候特征由相对湿润转向干旱;但在1100~0 cal. a BP期间偏高的δ15N值,则可能受到了增强的人类活动的影响．本研究表明,巴里坤湖沉积物δ15N记录对于恢复研究区全新世气候与环境变化的特征与历史等方面具有较好的应用潜力和前景．     

High－resolution precipitation variations in the Northeast Tibetan Plateau over the last 800 years documented by sediment cores of Qinghai Lake

Short cores of about 80-cm retrieved from three main basins of th e deepwater areas in Qinghai Lake,the largest inland enclosed lake in China, were studied. Sta-ble isotopes of authigenlc carbonates, grain-size, carbonate and organic matter content at 5-year resolution are used to reconstruct the climatic history over the last 800 years in the Northeastern Tibetan Plateau. Chronology was established according to 210^pb dating and 137^Cs methods and the core corrdation. It is found that cores from different deep basins of the lake can be well correlated. The sedimentary rate is highest in the western basin of the lake and lowest in the east.In the southern basin of the lake where the short core Qing-6is located, the recent average sedimentation rate is 0.1004cm/yr. Variations in effective precipitation recorded by the oxygen isotopes and grain size data durine the last 800 years are consistent with the glacial accumulation record form the Dunde and Guliya ice cores. A dry climate lasted for 300 years from 1200 AD to 1500 AD, followed by a wet period from 1500 to 1560 AD. The two dry periods, 1560 to 1650 AD and 1780 to 1850 AD, were the results of southwest monsoon weakening. The effective precipitation generally increased since 1650 AD due to the strengthening of the Asian South-west Monsoon, resulting in a wet period until the 1950s. Ex-cept the early stage, the Little Ice Age on the Plateau is characterized b y increased effective moisture. Organic mat-ter content, with nearly 200-year cycles, shows similar trend with the atmospheric delta earbon-14 before the 1850s, indi-eating that the bioproductivity responds to solar activity.     

东平湖地区地下水化学特征及质量评价

为分析东平湖周边地区地下水化学特征及地下水质量,运用离子分析、数理统计、Piper三线图及Gibbs图等方法,对研究区枯水期及丰水期溶解性总固体（TDS）时空分布、离子特征、水化学类型、影响因素和离子来源进行了分析;采用综合评价法对地下水水质进行了评价,并对其时空分布及水质成因进行了简析。结果表明：东平湖周边地区地下水TDS值普遍偏高,枯水期与丰水期空间分布规律差异不大;地下水中阳离子以Ca2+、Na+为主,阴离子以HCO3-、SO42-为主,水化学类型枯水期以HCO3?SO4-Ca?Na型水为主,丰水期以HCO3 -Ca?Na型水为主;枯水期地下水化学特征主要受岩石风化作用影响,部分受蒸发浓缩作用影响,离子主要来源为蒸发岩溶解及碳酸盐溶解的共同作用,丰水期主要受岩石风化作用影响,离子主要来源为碳酸盐溶解;研究区地下水水质相对较差,枯水期与丰水期水样中Ⅳ类水（较差）及Ⅴ类水（极差）占比均超过了50％,但丰水期Ⅱ（良好）、Ⅲ（较好）类水比枯水期同类水分布区域更广。     

陕西省冬季典型湿冷型与干暖型气候对比分析

目的通过陕西冬季历史典型湿冷型气候与典型干暖型气候的对比分析,为冬季的短期气候预测提供思路。方法采用气候统计诊断分析及天气气候动力学分析方法。结果典型湿冷型与干暖型气候在环流背景、海平面气压场、低层风场等方面表现出几乎相反的特征。结论典型湿冷型500 hPa乌拉尔山阻塞高压、咸海低槽长时间维持,青藏高原低值系统活跃,咸海低槽分裂冷空气与暖湿气流在陕西交汇,蒙古高压偏强,伴随有强冷空气南下;典型干暖型500 hPa欧亚地区中高纬度为两槽一脊型,欧洲西北部、鄂霍茨克海分别为一低槽,西伯利亚至巴尔喀什湖为强大的高压脊,形成"西高东低"的环流形势,蒙古高压系统偏弱。     

Centennial changes of drought/flood spatial pattern in eastern China for the last 2000 years

The statistical characteristics of the bicentennial changes of the drought/flood spatial pattern over the eastern part of China have been analyzed from 101 AD to 1900 AD, and their relationship with the cold/warm climatic variation in the same time span are discussed as well. The main conclusions are as follows. (I) During the period of the 2nd ～ 11th centuries, the spatial pattern of drought/flood in the eastern part of China was characterized by thc east-west differentiation. Namely, it was dry in the west (northwest) while it was wet in the east (southeast). (ii) From the 12th to 15th centuries, the east-west differentiation coexisted with the south-north differentiation, and the former was still the dominant pattern. (iii) However, the dominant spatial pattern changed to the south- north differentiation during the 16th ～ 19th centuries, namely, it was dry in the north and wet in the south. As for the dry-wet demarcation line. It shifted westward in warn times, and once reached Datong-Taiyuan-Xi' an-Hanzhong; whereas in cold times, it retreated southeastward and reached Ji' nan-Heze-Nanyang. Furthermore, the transmeridian (W-E) dry-wet demarcation line was replaced by the meridian (N-S) dry-wet demarcation line during the two coldest periods. Moreover, in cold times, it was dry in northern China, and it was wet in the middle and lower reaches of Changjiang River and regions south of Changjiang River; in warm times, however, it was wet in northern China, and was dry in eastern China, especially in the lower reaches of Changjiang River and regions south of Changjiang River.     

近300年来岱海流域气候干湿变化与人类活动的湖泊响应

根据岱海60cm柱状岩芯的磁化率、孢粉、粒度等环境指标的分析结果,对历史时期岱海气候干湿变化和人类活动的湖泊记录进行探讨,岱海湖泊沉积记录近300年来的气候干湿变化可划分七个阶段,与历史记载有较好的一致性;频率磁化率高值段对应气候偏湿阶段,低值对应气候偏干阶段,人类活动特别是人口增加和土地开垦,加剧流域水土流失,导致湖泊沉积物中细颗粒组分增加,频率磁化率升高;孢粉Ulmus的变化受流域人口增加的影响。频率磁化率和孢粉是反映岱海历史时期干湿变化和人类活动的重要环境指标。     

A 16000-year pollen record of Qinghai Lake and its paleo-climate and paleoenvironment

The paleoclimate and paleoenvironment of Qinghai Lake indicated by a 16000-year pollen record are as follows. It was very cold and dry before 15200 years. During the Late Glacial, the climate varied from colder and semiarid to cool and semi-humid and fluctuated frequently but with little amplitude. Three cold events in the periods of 13400–13000, 11600–12000, and 11000–10400 aBP respectively correspond to the Oldest Dryas, Older Dryas and Younger Dryas events, whereas the two warm periods between them, 12000–13000 and 11600–11000 aBP, respectively correspond to Bölling and Alleröd periods. The temperature increased abruptly after the Younger Dryas event, and then the climate gradually turned to be warm and wet from warm and semiarid. In the Holocene, the largest amplitude of cold event that occurred at ca. 8200 aBP is quite prominent. The Holocene climatic optimum culminated at 6700 aBP. After 2100 aBP, the climate tended to be cold and dry, keeping on up to now. Palaeoclimatic evolution and events of Qinghai Lake based on pollen assemblage and concentrations can be well parallel with the global climatic events.     

Interdecadal trend turning of global terrestrial temperature and precipitation during 1951-2002

A grid-by-grid counting of interdecadal trend turning (ITT) of annual mean surface air temperature (SAT) and total precipitation at 67,359 terrestrial grids in the period 1951-2002 is presented. An analysis of the last ITTs of SAT and total precipitation in the period, in the context of both occurrence time and linear trends after the breakpoint, indicates that a warming trend has become highly significant across most reagent of the world in the late 20th Century. Most terrestrial grids have recorded an ITT of total precipitation in either the 1970s or 1980s, and 45.7% of the terrestrial grids in the study have seen a decreasing trend in total annual precipitation after the breakpoint, with the remaining 54.3% having experienced an increasing trend. Basically, global terrestrial regions have experienced either an increasingly warm and dry climate or an increasingly warm and wet climate. An analysis of ITT of regional mean SAT and total precipitation in 22 regions shows that the Northern American continent has become increasingly warm and dry after the last interdecadal breakpoint. Meanwhile, the African continent has become increasingly warm and wet, with both Europe and most of Asia having the same trend. Southern South America and the West of Australia have experienced an opposite trend in climate, becoming increasingly cold and wet.