Historical Changes and Future Projections of Extreme Temperature and Precipitation along the Sichuan–Tibet Railway

Based on multiresource high-resolution in situ and satellite merged observations along with model simulations from the Coordinated Regional Climate Downscaling Experiment(CORDEX), this study first investigated historical changes in extreme temperature and precipitation during the period of 1979–2018 in areas along the Sichuan–Tibet Railway, and then projected the future changes in the frequency and intensity of extreme temperature and precipitation under the RCP(Representative Concentration Pathway) 4.5 and 8.5 scenarios. This paper is expected to enhance our understanding of the spatiotemporal variability in the extreme temperature and precipitation along the Sichuan–Tibet Railway, and to provide scientific basis to advance the Sichuan–Tibet Railway construction and operation. The results show that temperatures in the Sichuan–Tibet region display a noticeable warming trend in the past40 years, and the increase of minimum temperature is significantly higher than that of maximum temperature in the northwest of the region. Significant increase of precipitation is found mainly over the northwest of the Tibetan Plateau. Except for Lhasa and its surrounding areas, precipitation over other areas along the Sichuan–Tibet Railway shows no significant change in the past 40 years, as indicated in five datasets; however, precipitation along the railway has shown a remarkable decrease in the past 20 years in the TRMM satellite dataset. The warm days and nights have clearly increased by 6 and 5 day decade1-for 1979–2019, while cold days and nights have markedly decreased by about 6.6 and 3.6 day decade-1, respectively. In the past 20 years, the areas with increased precipitation from very wet days and extremely wet days are mainly distributed to the north of the Sichuan–Tibet Railway, while in the areas along the railway itself, the very wet days and extremely wet days are decreasing. Under RCPs 4.5 and 8.5, the temperature in the Sichuan–Tibet region will increase significantly, and the frequency of extreme high(low) temperature events in the late 21 st century(2070–2099) will greatly increase(decrease) by about 50%–80%(10%) compared with occurrences in the late 20 th century(1970–1999). Meanwhile, the frequency of very wet days and extremely wet days in the Sichuan–Tibet region will increase by about 2%–19% and 2%–5%, respectively, and the areas along the Sichuan–Tibet Railway will be affected by more extreme high temperature and extreme precipitation events.     

基于正交分解的非线性结构外荷载识别方法研究

提出一种基于切比雪夫正交分解的非线性结构外荷载识别方法及分解阶数确定办法.在识别过程中建立非线性结构体系状态空间方程,并将切比雪夫正交多项式展开系数扩展于状态量,对状态量进行递推估计.通过结构反应频域分析筛选频率范围并确定正交多项式项数.文中将通过6层隔震结构、波形钢腹板PC 组合梁桥的数值仿真和3层隔震框架的振动台试...     

河流年径流量的R/S灰色预测

径流过程具有分形和灰色特征。基于此,将R/S分析与灰色系统理论相结合,提出了R/S灰色预测模型以预报河流年径流量。针对黑河正义峡水文站60a(1949~2011年)的年径流量资料,首先进行R/S分析,确定径流量序列的Hurst指数H和平均循环周期T;然后在一个周期内进行年径流量灰色预测。结果表明:R/S灰色预测结果的精度明显高于直接进行灰色预测的精度。该方法拓宽了分形和灰色理论在径流过程研究的应用范围,为河流径流量的科学预测提供了一种新方法。     

沉积学研究在沉积和层控矿床勘查中的作用(代序)

这次贵州省重点矿产资源大精查,不仅要探明精查对象的资源储量,还要开展矿产形成、分布规律研究,为进一步的深部和外围预测奠定基础.贵州省的优势矿产资源,多数是沉积矿产和层控矿产.为了认识并掌握其形成、分布规律,需要深入开展沉积学研究,分析和判别其沉积相和沉积环境.本文以4个案例,说明了沉积学研究在本次优势矿产资源大精查中的...     

Atmospheric Structure Observed over the Antarctic Plateau and Its Response to a Prominent Blocking High Event

Studies on the atmospheric structure over the Antarctic Plateau are important for better understanding the weather and climate systems of polar regions.In the s...     

中国山地环境气象研究进展

中国山地环境气象学是研究中国山地与大气、自然环境之间相互作用的一门交叉学科.近数十年来,中国山地环境气象研究进展迅速.1960年以来,大气物理研究所多次参加中国科学院组织的山地综合科学考察,多学科的相互交叉促进了中国山地环境气象的研究,特别是在珠穆朗玛峰、天山托木尔峰和横断山脉山地环境气象、雅鲁藏布大峡谷环境气象研究等方面进展较快.为监测全球环境气象变化,中国气象局在青藏高原上设立了环境气象监测站.此外,在利用臭氧卫星资料研究青藏高原与臭氧分布、准两年振荡(QBO)信号、ENSO信号的关系方面也颇有进展.     

赞比亚东北部班韦乌卢地块泛非期以来构造演化的裂变径迹约束

本文利用锆石和磷灰石裂变径迹方法探讨了班韦乌卢地块泛非期以来的主要构造演化时间。为研究班韦乌卢地块的构造活动,本文从班韦乌卢地块中部卡帕图地区的沉积盖层姆波罗科索群的姆巴拉组、萨马组和卡布韦卢马组中采集多件新鲜的岩石样品,并获得5件锆石和2件磷灰石样品裂变径迹分析结果。5件锆石裂变径迹年龄介于575±35～380±22 Ma之间,其峰值年龄组为600～572 Ma和420～390 Ma。2件磷灰石裂变径迹年龄介于59±6～27±4 Ma之间,其峰值年龄组为99～80 Ma和19～11 Ma。它们的峰值年龄组分别对应的主要时代为新元古代的埃迪卡拉纪、早泥盆世、晚白垩世和中新世。对比区域上已有的年龄数据可知,南部非洲地区新元古代的埃迪卡拉纪、早泥盆世和晚白垩世的构造活动是一个区域性的构造事件,仅中新世(19～11 Ma)的构造活动在区域上的表现尚不明确。综合前人成果资料,自泛非构造运动以来,班韦乌卢地块至少经历600～572 Ma、488～441 Ma、420～390 Ma、375～293 Ma、99～80 Ma及19～11 Ma六个构造事件。班韦乌卢地块泛非期以来的构造演化研究程度很低,...     

The Tibetan Ozone Low and Its Long-Term Variation During 1979–2010

A Tibetan ozone low was found in the 1990s after the Antarctic ozone hole.Whether this ozone low has been recovering from the beginning of the 2000s following the global ozone recovery is an intriguing topic.With the most recent merged TOMS/SBUV(Total Ozone Mapping Spectrometer/Solar Backscatter Ultra Violet) ozone data,the Tibetan ozone low and its long-term variation during 1979-2010 are analyzed using a statistical regression model that includes the seasonal cycle,solar cycle,quasi-biennial oscillation(QBO),ENSO signal,and trends.The results show that the Tibetan ozone low maintains and may become more severe on average during 1979-2010,compared with its mean state in the periods before 2000,possibly caused by the stronger downward trend of total ozone concentration over the Tibet.Compared with the ozone variation over the non-Tibetan region along the same latitudes,the Tibetan ozone has a larger downward trend during 1979-2010,with a maximum value of-0.40±0.10 DU yr 1 in January,which suggests the strengthening of the Tibetan ozone low in contrast to the recovery of global ozone.Regression analyses show that the QBO signal plays an important role in determining the total ozone variation over the Tibet.In addition,the long-term ozone variation over the Tibetan region is largely affected by the thermal-dynamical proxies such as the lower stratospheric temperature,with its contribution reaching around 10% of the total ozone change,which is greatly different from that over the non-Tibetan region.     

赞比亚班韦乌卢变质克拉通东北部姆巴拉组碎屑锆石U-Pb年龄和Hf同位素特征

班韦乌卢变质克拉通活动时间和地壳增长问题一直是地质学家关注的焦点。本文通过对班韦乌卢地块中卡帕图地区姆波罗科索群姆巴拉组石英砂岩进行了碎屑锆石U-Pb年代学和Hf同位素研究,结合变质克拉通已有成果获得认识如下：(1)姆巴拉组的形成时间可能介于(1833±22 Ma)～(1712±22 Ma)之间,属于古元古代。(2)姆巴拉组具有丰富的物质来源,其中2728～2602 Ma(峰值为2650 Ma)的物质可能来源于坦桑尼亚克拉通中的花岗岩类、粗面安山岩及流纹岩等岩石。2246～1833 Ma(峰值为1880 Ma)的物质主要来源于班韦乌卢地块中花岗岩类、石英闪长岩及火山岩类等岩石。(3)班韦乌卢变质克拉通的活动时间包括中太古代、新太古代、古元古代和中元古代四个时期,其中古元古代(1870 Ma)为活动的高峰期,涉及范围广泛,可能与哥伦比亚超大陆的演化密切相关。(4)班韦乌卢变质克拉通沉积岩的源区地壳增生除来自古老地壳的再循环物质外,还存在新生地壳的物质。同时,地壳在古太古代-古元古代均实现了增长,其中凯诺兰超大陆聚合时期(2550 Ma)增长最快。在古元古代之前的地壳主增长期与坦桑尼亚克拉通及全球大陆地壳主增长期基本一致。     

纳米比亚金刚石矿床地质特征、矿床成因及找矿模型

纳米比亚金刚石资源丰富且品质优良,矿床类型以次生砂矿为主。文章对前人的大量研究成果进行分析总结,概述了纳米比亚金刚石矿床的区域地质背景,分析了金刚石矿床的地质特征及矿床成因。对纳米比亚金刚石包裹体氩-氩法定年分析发现,80%的包裹体熔蚀年龄<300Ma,表明大部分纳米比亚碎屑金刚石源自Dwyka期(<300Ma)以后的金伯利岩;纳米比亚金刚石以橄榄岩型(占比46%)和榴辉岩型(占比41%)为主,其余为二辉岩型或介于橄榄岩型-二辉岩型之间;纳米比亚橄榄岩型金刚石包裹体中石榴石-橄榄石平衡矿物的温度为961~1223℃,平均(1107±98)℃;石榴石-斜方辉石的平衡压力多为4.5~6.0GPa。纳米比亚金刚石的找矿有利地区主要为奥兰治河沿线及Oranjemund、卢得立次海岸地区,以次生金刚石砂矿为主。