2010—2100年淮河径流量变化情景预估   总被引：2，自引：0，他引：2       下载免费PDF全文

高超  曾小凡  苏布达  闻余华  朱进  吴必文 《气候变化研究进展》2010,6(1):15-21

根据淮河流域14个气象站点1964—2007年观测降水量与温度数据和ECHAM5/MPI-OM模式在3种排放情景下对该流域2001—2100年的气候预估,利用人工神经网络模型预估淮河蚌埠站2010—2100年逐月径流量变化。计算结果表明:3种排放情景下2010—2100年淮河径流量年际变化幅度差异较大,SRES-A2情景总体处于波动上升趋势,其中2051—2085年上升趋势显著;SRES-A1B情景2024—2037年年平均流量显著降低;SRES-B1情景年平均流量的变率甚小。季节分析表明:春季径流量在2010—2100年变幅最小,距平百分率在-15.1%～18.6%之间小幅波动。夏季平均流量在2040年代前呈下降趋势,之后小幅波动上升。秋、冬季平均流量SRES-A2和SRES-A1B情景变幅显著,其中,秋季SRES-A2情景2060年代距平百分率下降达50.6%,为3种情景下各季节径流量降幅之最;冬季SRES-A1B情景2050年代其增幅达到54.7%,亦为上升幅度之最。  相似文献   

宇宙成因核素~(21)Ne测年原理和应用   总被引：1，自引：1，他引：0  

马严  武颖  庞建章  张会平  郑德文 《地震地质》2015,37(1)

宇宙成因核素测年方法在地表暴露测年和沉积物埋藏测年方面均具有重要应用价值,还可用于定量计算地表侵蚀、地形抬升和河流下切等反映气候及构造运动影响的地表过程速率,对研究地球各圈层之间的相互作用关系具有重要意义,是第四纪年代学领域中一种重要的测年方法。与放射性宇宙成因核素10Be、26Al相比,稳定核素21Ne在地表暴露定年方面具有测年范围宽、测年材料选择范围广、测试所需样品量少、前处理过程简单等优点。通过与放射性核素的结合使用,稳定核素21Ne还可用于沉积物的埋藏测年,并具有比10Be-26Al埋藏测年法更高的测年上限和测年精度。稳定核素21Ne测年方法的应用在国内尚处于起步阶段,但可以预见,这一方法将以其独特的优势在第四纪地质学、地貌演化及活动构造等诸多研究领域得到广泛的应用。  相似文献   

晋县凹陷未熟蒸发岩沉积物中C22-C27甾烯和C24-C30四环萜烷的检出     

陈腾水  徐忠辉  刘菊  卢鸿  盛国英  彭平安  Kliti Grice  Paul Greenwood 《地球化学》2009,38(3):289-298

晋县凹陷赵芯2井（2459m,Ezk）低熟蒸发岩样品中检出了异常分布的C22-C27甾烯和C24-C30四环萜烷（17,21-断藿烷）,但在同井更深、成熟度相对更高的沉积物中并未检出。实测镜质组反射率R^0=0．43％以及芳烃馏分中有高丰度的苯并噻吩和多烷基化的二苯并噻吩,说明热催化作用成因是不可能的,微生物参与成为最可能的生成途经。沉积抽提物未显示出常规生物降解的痕迹,因此这些化合物很可能是在早期成岩阶段特定微生物作用的结果。该区油样中检出的C21-C29甾烷的特征与同时检出的C22-C27甾烯特征一致,进一步表明微生物作用的可能性;高丰度的C24-C30四环萜烷（17,21-断藿烷）和常规藿烷、甲基藿烷相匹配,以及高丰度的C22-C27甾烯和规则甾烷缺失相匹配,特别是芳烃馏分中多取代二苯并噻吩类有机含硫化合物的检出,均表明异常分布的C22-C27甾烯与C24-C30四环萜烷类似,很可能是早期成岩阶段微生物改造作用下的产物。  相似文献   

沾化凹陷渤南洼陷沙一段湖相富有机质烃源岩岩石学与孔隙结构特征:以罗63井和义21井取心段为例     

李志明  张隽  鲍云杰  曹婷婷  徐二社  芮晓庆  陈红宇  杨琦  张庆珍 《吉林大学学报(地球科学版)》2018,48(1):39-52

以沾化凹陷渤南洼陷罗63井和义21井沙一段取心段为例,依据研究样品的热解、全岩与黏土矿物X射线衍射、有机岩石学、孔隙度、氩离子抛光+扫描电镜以及微孔隙结构等分析结果,开展了沙一段湖相富有机质烃源岩岩石学与孔隙结构特征研究,结果表明：罗63井和义21井沙一段取心段富有机质烃源岩主要由碳酸盐矿物、黏土矿物和石英组成,另含少量长石、黄铁矿和石膏,其中黏土矿物主要由伊/蒙混层、伊利石组成,由取心段顶部至底部,碳酸盐矿物质量分数明显增高,而黏土矿物和石英则显著降低,呈现由钙质或灰质泥岩至演变为泥质灰岩的特征,岩石构造类型包括层状、纹层状和块状3类;罗63井和义21井沙一段取心段富有机质烃源岩平均孔隙度分别为2.09%和4.43%,具纹层状构造的烃源岩具有相对高的孔隙度;主要发育矿物基质孔隙（即粒间孔隙和粒内孔隙）和裂缝型孔隙两大类,而有机质孔隙不发育,孔隙半径从十几微米至几纳米的孔隙均有分布,以发育孔径50 nm以上的宏孔为主。  相似文献   

水文科学研究的世纪回眸与展望   总被引：44，自引：4，他引：40       下载免费PDF全文

叶守泽  夏军 《水科学进展》2002,13(1):93-104

对20世纪国内外水文科学发展历程进行了回顾,涉及到水文学的变革、水文测验、水文分析计算、水文模拟与预报和主要水文分支学科的兴起。对当今水文学术界的争论问题阐明了笔者的观点,其中涉及到科学与技术的关系、科学研究与生产应用的关系,数学方法与水文物理基础的关系。指出了我国水文学术界存在的若干问题。对21世纪水文科学的发展进行了展望。  相似文献   

Climate Change Projections for the 21st Century by the NCC/IAP T63 Model with SRES Scenarios   总被引：10，自引：1，他引：10       下载免费PDF全文

XU Ying  ZHAO Zongci  LUO Yong  GAO Xuejie 《Acta Meteorologica Sinica》2005,19(4):407-417

1. IntroductionFor the latest 15 years, the climate change hasbeen paid more attention by the policy-makers, scien-tists, and the public. The global warming of 0.4-0.8°Cfor the 20th century has been measured by the instru-mental observations. The atmospheric concentrationof CO2 increased from 280 ppm for the period 1000-1750 to 368 ppm in the year 2000 with an increase of27%-35%. In the light of new evidence and taking intoaccount the remaining uncertainties, most of the ob-served warming o…  相似文献   

Networking for Local Agenda 21 implementation: Learning from experiences with Udaltalde and Udalsarea in the Basque autonomous community     

José M. Barrutia  Carmen Echebarria 《Geoforum》2007,38(1):33-48

Local Agenda 21 (LA21) is widely regarded as a key tool for implementing sustainability policies since local authorities are closer to ordinary people and some local managers and politicians have the ability to adapt organisations to new managerial atmospheres and social demands. However, local governments tend to lack the right economic, human and knowledge resources. Consequently, in the search for local sustainable development, networking and collaborative approaches to LA21 can help local authorities save resources and share knowledge and best practices. Although both research and politicians have tended to focus on LA21, we believe Regional Agenda 21 (RA21) needs to be emphasised as a complementary tool. This paper examines successful innovative practices in the Basque Autonomous Community (BAC) over a 4-year period, with a view to shedding light on the theoretical literature and to aiding regional and local authorities. Although research on policy networks has produced useful results, we are still some way from a plausible, consensus-based theory of policy networks. Based on experience in the BAC, the present article offers an integrated approach to understanding the antecedents and consequences of a regional knowledge-driven network for LA21 promotion. Although LA21 implementation has been studied before, evidence about networking at regional level is scarce. Other regions in developing countries could use this approach to achieve successful policy networks.  相似文献   

利用北斗/GNSS观测数据分析“21·7”河南极端暴雨过程     

施闯  周凌昊  范磊  张卫星  曹云昌  王成  肖锋  吕国卿  梁宏 《地球物理学报》2022,65(1):186-196

2021年7月,受台风“烟花”和“查帕卡”影响,河南省发生罕见的极端暴雨事件,造成了重大人员伤亡和巨额经济损失.极端暴雨的产生过程极为复杂,大气可降水含量(PWV)是产生降雨的主要因素之一.分析暴雨的发生过程与PWV之间的关系,对于暴雨发生的短时临近预报具有重要意义.本文利用河南省220个连续运行的北斗/GNSS站观测数据,采用精密单点定位(PPP)和克里金插值方法,获取了本次极端暴雨发生期间河南省高时空分辨率的PWV空间格网数据;同时结合省内116个气象站降雨量数据,分别从时间和空间上分析了PWV变化与极端降雨之间的关系.结果表明,通过PPP获取的北斗/GNSS站PWV与国际权威的全球气象再分析资料ERA5反演的测站结果互差均方根(RMS)为3.2 mm;进一步通过克里金插值获取的PWV空间格网数据与探空仪实测结果的互差RMS为4.6 mm,与ERA5反演的格网数据互差RMS为4.4 mm,表明本文的PWV数据精度符合气象学研究要求.通过分析北斗/GNSS站与并址气象站的PWV和小时降雨量的时间序列,发现暴雨期间并址站上空的PWV达到高数值水平,并且在极端降雨发生前1~3小时PWV多表现出陡增现象.通过分析PWV与小时降雨量的空间分布关系,发现本次极端暴雨中高数值PWV地区,其降雨强度也普遍较高,与实际受灾情况相符.  相似文献   

Resource-based view of sustainability engagement     

《Global Environmental Change》2015

This research examines local sustainability planning processes under the label of Local Agenda 21 in Italy from a resource-based view. Two types of resources, municipal (or internal resources) and relational resources, are considered. Relational resources stem from (1) dyadic relationships with higher levels of government and (2) network relationships (municipality-higher level of government-municipality). A model is proposed in which the integration of these resources explains the engagement of municipal authorities with Local Agenda 21-type processes. The model is tested by considering the perceptions of 108 local senior officials and politicians who are in charge of Local Agenda 21 processes in Italy. The respondents account for 31% of the members of a formal Italian Local Agenda 21 network. The results show moderate to low engagement with Local Agenda 21 processes, which is explained by moderate to poor levels of relational resources. Our findings indicate that local authority engagement with Local Agenda 21-type processes requires a systemic perspective, where higher levels of government and municipalities integrate and combine their resources and create new purposefully led resources through regular and intense interactions.  相似文献   

Millisecond pulsars     

D. C. Backer 《Journal of Astrophysics and Astronomy》1984,5(3):187-207

In 1982 we discovered a pulsar with the phenomenal rotation rate of 642 Hz, 20 times faster than the spin rate of the Crab pulsar. The absence of supernova debris in the vicinity of the pulsar at any wavelength indicates an age of the neutron star greater than 10⁵ yr. The miniscule spindown rate of 1.1 × 10^-19 confirms the old age and indicates a surface magnetic field of 10⁹ G. A second millisecond pulsar was discovered by Boriakoff, Buccheri & Fauci (1983) in a 120-day orbit. These fast pulsars may have been spun-up by mass transfer in a close binary evolutionary stage. Arrival-time observations of the 642-Hz pulsar display remarkably low residuals over the first 14 months. The stability implied by these observations, 3 × 10^-14, suggests that millisecond pulsars will provide the most accurate basis for terrestrial dynamical time. If so, the pulsar data will lead to improvements in the planetary ephemeris and to new searches for light-year scale gravitational waves. Many new searches for fast pulsars are under way since previous sky surveys excluded pulsars with spins above 60 Hz.  相似文献