乌鲁木齐逐月气温资料均一化检验和订正

选用1951-2008年乌鲁木齐市气象站逐月最高、最低及平均气温资料,用标准正态检验（SNHT）方法对逐月气温资料序列进行均一化检验,并选用差值法对因迁站引起的断点资料进行订正,检验结果显示,月气温序列断点所在的年份与年序列中检验出的断点基本相对应,即气温资料均在迁站距离较远的1975年产生了断点;各月的检验结果存在一定的差异,5-9月气温较高的月份资料受迁站的影响较大,而且产生了断点,并通过了0.05的显著性水平。用不同的权重比例对月序列进行订正,并选择累积距平方法对5-9月气温序列订正前后的变化趋势作了比较分析,发现订正前后趋势确有较显著的变化。     

Past,present and future vegetation-cloud feedbacks in the Amazon Basin

To begin exploring the underlying mechanisms that couple vegetation to cloud formation processes, we derive the lifting condensation level (LCL) to estimate cumulus cloud base height. Using a fully coupled land–ocean–atmosphere general circulation model (HadCM3LC), we investigate Amazonian forest feedbacks on cloud formation over three geological periods; modern-day (a.d. 1970–1990), the last glacial maximum (LGM; 21 kya), and under a future climate scenario (IS92a; a.d. 2070–2090). Results indicate that for both past and future climate scenarios, LCL is higher relative to modern-day. Statistical analyses indicate that the 800 m increase in LCL during the LGM is related primarily to the drier atmosphere promoted by lower tropical sea surface temperatures. In contrast, the predicted 1,000 m increase in LCL in the future scenario is the result of a large increase in surface temperature and reduced vegetation cover.     

中国东北地区近百年气温序列的小波分析

 利用1905-2005年中国东北地区哈尔滨、长春、沈阳和大连的气温时间序列资料,在分析气温变化结构的基础上进行小波分析,以揭示气温变化的多时间尺度的复杂结构。同时,分析了不同时间尺度下气温序列变化的周期性变化规律和突变点。结果表明：近100 a来中国东北地区的平均气温呈升高趋势,尤其在20世纪80年代以后升高趋势更加显著,升温率达到0.165 ℃/10 a。气温存在2～3 a、8～12 a、20～25 a和45 a左右时间尺度的多重时间尺度结构的变化特征。     

Climatic implications of correlated Upper Pleistocene glacial and fluvial deposits on the Cinca and Gállego Rivers (NE Spain) based on OSL dating and soil stratigraphy

We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gállego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 ± 5 ka, 64 ± 11 ka, and 36 ± 3 ka (from glacial till) and 20 ± 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 ± 21 ka, 97 ± 16 ka, 61 ± 4 ka, 47 ± 4 ka, and 11 ± 1 ka, and in the Gállego River valley at 151 ± 11 ka, 68 ± 7 ka, and 45 ± 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and Heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 ± 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 ± 4 ka) and Gállego (68 ± 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to 1) global climate changes controlled by insolation, 2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and 3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian Peninsula. Our scenario of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.     

Sedimentary and faunal events revealed by a revised correlation of post‐glacial Hirnantian (Late Ordovician) strata in the Welsh Basin,UK

The discovery of a previously unrecognized unconformity and of new faunas in the type Llandovery area underpins a revised correlation of Hirnantian strata in mid Wales. This has revealed the sedimentary and faunal events which affected the Lower Palaeozoic Welsh Basin during the global rise in sea level that followed the end‐Ordovician glacial maximum and has allowed their interpretation in the context of local and global influences. In peri‐basinal shelfal settings the onset of post‐glacial deepening is recorded by an unfossiliferous, transgressive shoreface sequence (Cwm Clyd Sandstone and Garth House formations) which rests unconformably on Rawtheyan rocks, deformed during an episode of pre‐Hirnantian tectonism. In the deep water facies of the basin centre, this same sequence boundary is now recognized as the contact between fine‐grained, re‐sedimented mudstones and an underlying regressive sequence of turbidite sandstones and conglomerates; it is at a level lower than previously cited and calls into question the established lithostratigraphy. In younger Hirnantian strata, graptolites associated with the newly recognized Ystradwalter Member (Chwefri Formation) demonstrate that this distal shelf unit correlates with the persculptus graptolite‐bearing Mottled Mudstone Member of the basinal succession. Together these members record an important macrofaunal recolonization of the Welsh Basin and mark a key event in the post‐glacial transgression. Further deepening saw the establishment of a stratified water column and the imposition of anoxic bottom water conditions across the basin floor. These post‐glacial Hirnantian events are consistent with the re‐establishment of connections between a silled Welsh Basin and the open Iapetus Ocean. However, a comparison with other areas suggests that each event records a separate deepening episode within a pulsed glacio‐eustatic transgression, while also reflecting changes in post‐glacial climate and patterns of oceanic circulation and associated biotic flux. British Geological Survey © NERC 2009. All rights reserved.     

末次冰期黄河解体事件初探

７０年代末，水文地质部门在华北平原上打下了大量第四系钻孔，１９９３年对其中近百个钻孔的沉积相和测年资料重新进行分析，发现在该区全新统之下、上更新统上部普遍发育了一层细砂层，埋深一般为２０－４０ｍ，厚度约为５－２０ｍ，平面分布连续而稳定。     

云南点苍山冰川湖泊沉积物磁化率的影响因素及其环境意义

文章通过对点苍山海拔3820m冰水沉积剖面的粒度参数、磁化率、氧化铁含量和有机质含量的综合实验分析,并讨论了这些指标的相互关系及其环境意义。实验结果表明,磁化率的强度与粗砂组分的含量成正相关,而与粘土等细粒组分含量成负相关;同时与有机质含量成负相关,与氧化铁含量成正相关。矿物组分分析实验表明,沉积物主要磁性来源于磁化铁。根据以上结果,结合冰川湖泊流域面积小、高寒环境的特点,其磁化率的影响因素与一般湖泊不同,认为冰川湖泊沉积中,因为物源较近导致外源磁性矿物主要赋存于粒度较粗的碎屑颗粒中,而高寒的环境条件使得有机质对沉积物的磁性矿物起到了稀释的作用,而很难有积极的贡献。根据磁化率的环境意义,恢复了全新世以来点苍山的古气候,从中可以划分6个不同的气候阶段:11.5～10.6kaB.P.,10.6～8.9kaB.P.,8.9～5.5kaB.P.,5.5～3.3kaB.P.,3.3～0.8kaB.P.和0.8kaB.P.至今,代表了末次冰期结束以后湖泊从产生至消亡的全过程。根据与其他相关地区的对比,分析了西南季风演变的一些规律。     

继承性宇生核素对暴露测年结果影响的定量分析方法探讨

宇生核素暴露测年过程中,通常假设在样品最后一次暴露前,样品中的宇生核素（继承性宇生核素）浓度为0。然而,大量的测年数据研究发现,样品的暴露年代结果会受到继承性核素的影响从而高估地貌的真实年代。因此,如何降低继承性核素对暴露年代结果的影响或者定量分析继承性核素的影响程度不仅可为地貌演化提供准确的年代数据,而且对宇生核素暴露测年技术的研究具有重要意义。因此,本文以宇生核素暴露测年技术在冰川地貌中应用为例,通过分析继承性核素的研究概况,并结合宇生核素暴露测年原理,探讨继承性核素对测年结果影响的定量分析方法。研究结果表明： ① 通过样品中 n ( 26 Al)/ n ( 10 Be) 值\[即同一样品中宇生核素Al 26 与Be 10 浓度（单位为atom/g）的比值\]以及同一地貌位置多个的样品年代数据分布情况可初步判断测年结果是否受到继承性核素的影响;② 通过现代冰川冰碛物中宇生核素的浓度可以定量分析继承性核素对暴露测年结果的影响; ③ 通过计算冰碛垄顶部和一定深度（＞2~3 m）样品的宇生核素浓度差,可以减少继承性核素的影响。本研究内容对冰川地貌宇生核素暴露测年具有重要意义。     

1959-2017年天山乌鲁木齐河源1号冰川流域径流及其组分变化

冰川是气候变化的指示器,气候变化对冰川及其径流的影响研究是目前国内外关注的热点和前沿领域之一,目前的研究以模拟为主,实测资料十分有限且不确定性很大。以新疆天山乌鲁木齐河源1号冰川（简称“1号冰川”）流域为例,基于中国科学院天山冰川观测试验站1959-2017年观测数据,研究了中国西部典型小型冰川流域径流及其组分长期变化以及对气候变化的响应,为冰川径流长期变化过程的认识提供重要参考。结果表明,1号冰川流域径流主要由冰川径流和非冰川区降水径流组成,分别占70%和30%。其中冰川径流又可分为冰川区降水径流和冰川融水径流,分别占44%和26%。59年间,冰川径流整体呈上升趋势,在1992年之后出现了一个阶梯式的上升,与气温升高和降水的增加有关,1997-2007年达到高峰,2008年以后出现波动下降趋势,其原因除了与该时段的降水有所减少有关之外,冰川面积减小的影响也不可忽视。另外,还利用实测径流和冰川物质平衡值,通过水量平衡模型,检验了模型使用的冰川区和非冰川区径流系数。