积云对流参数化方案对东亚夏季环流和降水模拟的影响   总被引：3，自引：0，他引：3  

刘伟光  陈海山  俞淼 《大气科学》2019,43(1):64-74

利用WRF（Weather Research and Forecasting）模式对东亚夏季区域气候模拟中最常选用的两种积云对流参数化方案进行对比分析,研究积云对流参数化方案选用对大尺度环流模拟的影响。结果表明:Kain-Fritsch（KF）方案对西太平洋副热带高压（简称副高）及环流的模拟效果较好,虽然KF方案模拟降水偏多,但是时空分布与TRMM降水分布接近;Grell-Freitas（GF）方案对流加热率过大,从而模拟的南海—菲律宾区域对流异常增强,在南海—菲律宾洋面上的垂直输送异常增大,非绝热加热的范围偏大,导致副高南侧下沉区辐散减弱,抑制了副高北抬西伸,进而影响到水汽输送和季风环流,最终对东亚夏季降水的模拟产生不利影响。修改GF方案对流加热率和干燥率的敏感性试验表明,减小对流加热率和干燥率参数能有效抑制南海—菲律宾区域过强的对流,东亚大尺度环流的模拟得到明显改进。  相似文献   

微波雷达在嫦娥探月工程中的应用     

丁春雨  刘凯军  黄少鹏  苏彦  李佳威 《地质学报》2021,95(9):2805-2822

微波穿透雷达对月球的观测方式可以分为地基、星载环绕、星地联合以及就位探测等.对比其他探测手段,微波雷达在探测范围和空间分辨率上有很明显的优势,因此在月球和其他行星探测中起着重要的作用.国内外越来越多的深空探测任务已经或准备携带微波雷达,用于探索地外天体的浅表层地质结构,以了解行星地质过程和演化历史.本文综述了我国嫦娥三号和四号月球车玉兔号和玉兔2 号在就位微波雷达(测月雷达)探测月球浅表层地质结构方面所取得的新进展,重点阐述了测月雷达在揭示月壤内部的精细结构、表层与次表层地质结构探测等方面的应用.最后,展望了我国月球微波雷达的发展趋势.  相似文献   

环太平洋成矿带斑岩-矽卡岩型铜矿和与花岗岩有关的锡多金属矿研究现状与展望   总被引：8，自引：6，他引：2  

毛景文  谢桂青  袁顺达  刘鹏  孟旭阳  周振华  郑伟 《岩石学报》2018,34(9):2501-2517

长期以来,斑岩型铜矿是研究和勘查的热点。在20世纪70~90年代,对与花岗岩有关锡矿进行了大量深入研究,近几年,锡被列为一种关键金属,锡矿的研究和勘查又成为新的热点之一。锡矿和铜矿是环太平洋地区乃至全球最重要的两种矿床,但两者的成矿物质和成矿过程相差迥异。环太平洋地区的锡矿和铜矿主要形成于晚中生代至新生代,通常认为与太平洋板块俯冲有关,包括古太平洋板块、伊泽奈岐板块、法拉龙板块以及现今太平洋板块。本文主要综述了环太平洋成矿域的斑岩-矽卡岩铜矿和与花岗岩有关锡矿的时空分布特点、成矿岩体、矿床成因以及成矿环境的研究现状。尽管,目前已经取得了诸多重要进展,但仍然存在一些重要的科学问题亟待解决,例如,1)中国东部平行同时代成对出现的三条锡(钨)成矿带与斑岩铜矿成矿带的形成机制? 2)沿欧亚大陆边缘发育长达一万多公里的巨型铜金锡成矿带,而且绝大多数矿产发育于一系列伸展盆地中,其成矿背景是什么?此外,我们认为开展玻利维亚和大兴安岭南段Sn-Ag成矿系统的对比研究,是推动大兴安岭南段及邻区锡矿找矿取得突破的重要途径。  相似文献   

Geochemical and Mineral Characteristics of Jurassic Volcanic Rocks from ODP Sites 304, 1149, and 801: Implications for Magmatic Evolution in the Northwest Pacific     

CHEN Shuangshuang  LIU Jiaqi  Patrick RIOUAL  GUO Zhengfu 《《地质学报》英文版》2018,92(3):915-934

The regular variations in magmatic activities along the Northwest Pacific plate have been little studied in spite of their importance. In this contribution, systematic analyses were conducted on tholeiitic basalts from three Ocean Drilling Program sites (Sites 304, 1149, and 801), including the petrographic features, major and trace elements, Nd isotopic compositions, and mineral structure and compositions of whole rocks. Volcanic rocks from Sites 304, 1149, and 801 belong to tholeiites and exhibit depleted light rare earth elements (LREE), large ion lithophile elemental contents (LILE), and relatively depleted Nd isotopic ratios (143Nd/144Nd=0.513139–0.513211), similar to those of normal mid-ocean ridge basalts (N-MORB). Comprehensive data on mineral compositions, whole-rock geochemistry, and geochronology demonstrate that a regular variation trend exists in the north-south direction along the Northwest Pacific plate. The 143Nd/144Nd values (0.513139–0.513211) and trace-element ratios for whole rocks (Sm/Th=15.35–30.00; Zr/Hf=28.53–35.76; Zr/Y=2.58–3.67; Th/La=0.04–0.06; Th/Y=0.33–0.70), as well as the trace-element ratios (Zr/Hf, La/Yb, Ti/Zr) of clinopyroxenes from Sites 1149 and 801 tholeiites show larger variations compared to those from Site 304 tholeiites (143Nd/144Nd=0.513185–0.513195; Sm/Th=18.19–20.58; Zr/Hf=31.07–33.26; Zr/Y=2.62–3.03; Th/La=0.05–0.06; Th/Y=0.48–0.57). Mineral zoning textures were obvious in tholeiites from Sites 1149 and 801 but were rarely observed in Site 304. These regular features were likely attributed to the differences in the heterogeneity of the magma source, the process of magmatic evolution, the plate-spreading rate, and the effective and ineffective mixing.  相似文献   

A Participatory GIS Approach to Identify Critical Land Degradation Areas and Prioritize Soil Conservation for Mountainous Olive Groves （Case Study）   总被引：1，自引：0，他引：1  

Ahmed AL-WADAEY  ;Feras ZIADAT 《山地科学学报》2014,11(3):782-791

Climate change scenarios predict an increase in the frequency of heavy rainfall events in some areas. This will increase runoff and soil erosion, and reduce agricultural productivity, particularly on vulnerable mountainous agricultural lands that is already exhibiting high rates of soil erosion. Haphazard implementation of soil and water conservation （SWC） interventions on scattered fields is inefficient in reducing soil erosion. The objective of this study was to identify areas at high risk of erosion to aid the design and implementation of sustainable SWC using GIS analysis and farmers＇ participation approach. A 25 m digital elevation model （DEM） was used to derive layers of flow accumulation, slope steepness and land curvature, which were used to derive an erosion-risk （priority） map for the whole watershed. Boundaries of farmers＇ fields were mapped and verified by the community and each field was classified into high, moderate or low erosion risk. Fields with low flow accumulation （top of hill） and/or steep slope and/or convex slope were assigned high erosion risk and therefore high implementation priority. The study showed that more than 54% of the fields were classified into high erosion risk areas. Accordingly, a community-watershed plan was established, revised and approved by the community.Incentive loans to implement SWC measures were distributed to 100 farmers based on the priorities of their fields. Judged by local farmers and using 16 randomly selected fields, 90% of the targeted areas were correctly identified using the erosion risk map. After two years, the conservation measures had led to marked improvement of soil conservation. The approach is simple and easy to comprehend by the community and provides scientific basis to prioritize the implementation of SWC and to target the most degraded areas, which amplify the impact of these in reducing the vulnerability to land degradation.  相似文献   

Same Disease—different research strategies: Bananas and Black Sigatoka in Brazil and Colombia     

Diana Cordoba  Kees Jansen 《Singapore journal of tropical geography》2014,35(3):345-361

Fungal disease epidemics have the potential to bring about drastic innovations. However, in the case of the Black Sigatoka (Mycosphaerella fijiensis) fungus in bananas, producers and international traders are still awaiting a breakthrough in crop protection research. Using the cases of Brazil and Colombia, this paper examines different agricultural research responses to the disease. Brazil opted to replace susceptible varieties with resistant ones, whereas in Colombia chemical control by private actors dominated. We argue that these different responses result from at least three interrelated factors. First, producer type—smallholder farmers or larger export‐oriented plantations—influences the setting of crop protection research priorities. Second, a central, state‐led role versus a private sector response influences the size and time perspective of research activities. Third, domestic markets with multiple crop varieties versus Cavendish‐only export markets leads to differences in control practices and research responses. From this case study, we argue that the currently proposed innovation systems approaches in international agricultural research should adopt a broader perspective that assesses how research is interwoven with agrarian dynamics, commodity chains and particular state roles to elucidate how state–producer–researcher networks perform disease control and where and how to find new solutions.  相似文献   

关于测量大口径HDD环空泥浆固结特性新方法的研究     

祝赫  解经宇  张伟 《岩土钻凿工程》2012,(2):67-70

水平定向钻进（HofizontNDirecfionl Drilling,简称HDD）是采用安装于地表的钻孔设备。对于大直径管道来说,工程竣工后在钻孔和管道之间要留下300mm-400mm的环状间隙。要对泥浆固结后进行应力应变的分析,前提是要知道环空泥浆的固结时间。而传统测量环空泥浆的固结时间的方法存在着很多问题与缺陷,这也导致了时间检测上面误差较大,从而耽误了研究泥浆固结后受力分析的最佳时间。因此,弄清泥浆固结时间的变化规律非常必要,而目前国内在判定泥浆固结时间的方法上仍处于空白阶段。针对这一状况．本人设计采用两种方法进行固结时间的判定,通过湿度传感器测量环空泥浆间隙的水蒸气含量进行泥浆固结时间的判定。  相似文献   

The scientific value of scientific whaling     

《Marine Policy》2016

Scientific whaling has polarized opinion for decades, and its scientific value has been intensely debated. Here, the output of scientific whaling programs is examined by comparing it to the scientific output pertaining to whales of countries that do not practice scientific whaling. Between 1986 and 2013, whaling and non-whaling countries produced, on average, similar total numbers of publications that were directly relevant to the goals of the scientific whaling permits issued by the International Whaling Commission (IWC), and similar numbers of papers that were relevant to whale ecology and conservation but not directly related to IWC goals. Half of the scientific productivity of scientific whaling countries resulted from non-lethal data collection. One-third of publications by whaling countries were published in peer-reviewed outlets, compared to twice as many for non-whaling countries. Publications by whaling countries were cited ~4 times less often than those of non-whaling countries, with no evidence of citation discrimination against whaling countries since the citation rates of papers that did and did not use lethal sampling were similar. These academic criteria suggest that although the overall volume of science produced by scientific whaling countries is similar to that of non-whaling countries, the quality of the science is not. Arguably, academic criteria are not the best way to assess the usefulness of science for management and conservation, but demonstrating links between the science produced by scientific whaling, its integration in management plans and actions, and shifts towards sustainable exploitation or recovery of whale populations is challenging.  相似文献   

论海洋强国之战略抉择与实践路径          下载免费PDF全文

董加伟  王盛 《海洋开发与管理》2016,33(5):46-49

海洋强国是中国以两个"百年计划"为基础、以实现民族伟大复兴为目标,总结历史、立足当下、展望未来做出的重大战略抉择。海洋强国战略的推进是一个长期、宏大的系统工程,既要加强顶层设计,更要着力推动实践。文章从必然性和必要性两个角度论述了中国实施海洋强国战略的合理性、正当性,进而从意识养成、理念更新、制度完善、体制重构等4个层面提出了推进海洋强国战略的实践路径。  相似文献   

北京地区基础地质研究史   总被引：1，自引：0，他引：1  

吕金波 《城市地质》2014,(3):8-13

北京素有“中国地质工作摇篮”之称,是中国最早开展地质调查的地方,从1863年9月美国学者庞培莱调查京西地质开始,已有150多年的历史。中国学者编写了第一部基础地质专著《北京西山地质志》;民国时期“燕山运动”的提出和“北京猿人”的发现成为影响全国乃至世界的基础地质重大成果;解放后,地质工作者在北京率先实现1∶5万区域地质调查的全覆盖,出版了《北京市区域地质志》和《北京猿人遗址综合研究》;在唐山大地震后,开展北京平原基础地质的综合研究,提升北京区域地质研究程度。北京现在和将来的城市地质调查应立足于基础地质研究。  相似文献