积云参数化和微物理方案不同组合应用对台风路径模拟效果的影响

利用美国国家环境预测中心(National Centers for Environmental Prediction,NCEP)和国家大气研究中心(NCAR)联合研发的天气研究和预报模式(Weather Research and Forecasting Model,WRF),研究了不同积云对流参数化方案和微物理过程方案对0514号台风"彩蝶"路径的影响.结果表明,积云对流参数化方案对台风路径影响较大,KF方案比BM方案能更好地模拟出台风路径;使用KF方案时,选择微物理方案比不选微物理方案对于台风路径有更好的模拟结果,其中,Ferrier、WSM6和Lin非常接近于实况;KF方案较好地模拟出副热带高压(简称副高)的西伸和东退的变化以及台风环流的风场分布和强度.     

THE START AND EARLY HISTORY OF CHEMOMETRICS:SELECTED INTERVIEWS.PART 2

This is a first foray into the historical start and early years of chemometrics from about 1972 onwards.We have gathered interviews with three originators(Kowalski,Wold and Massart)as well as with aselected group of six other well-known chemometricians who gradually became active in the 1970s(Christie,Clementi,Hopke,Martens,Brown and Deming).The interviews include amongst a host ofsubjective recollections a succinct record of the key historical literature as highlighted by the interviewees'own rankings of‘earliest’and‘best’.A discussion of the most general commonalities in these interviews together with other historicalmaterial is presented in the second part of the paper.     

Vegetative succession and controlled fire in a glades ecosystem A geographical information system approach

Abstract

A geographical information system (GIS) approach was used successfully on a federal wilderness area in southwestern Missouri to examine vegetative succession relative to fire management in a glades ecosystem. Maps of vegetation were obtained by interpreting aerial photographs taken in 1938, 1958, 1966, 1975 and 1986. Maps of topography, streams, soils and the location of fires which burned during the period 1938 to 1986 were also procured from a variety of public agencies. All maps were digitized and incorporated into a raster-based GIS with 25 m pixels. It was concluded that (1) both glades and oak-hickory forest have an affinity for distinct physiographic areas and (2) fire can help decrease the rate of processes of natural succession which cause glades to convert to forest. The probable effects of controlled fire on three areas proposed by the Forest Service were evaluated and summarized.     

国际经济地理学研究的知识图谱分析

基于Web of Science核心数据库收录的1982－2020年7 260篇期刊论文及其参考文献,借助CiteSpace绘制国际经济地理学的知识图谱,梳理该领域的知识基础、研究热点和研究前沿。结果发现：1）知识基础的演进轨迹遵循了新区域主义——制度、社会、文化、演化转向的时序变化,21世纪以来,关系、演化经济地理学下的经典文献成为主要的知识来源。2）研究热点突出,创新和增长始终是研究核心,近年来韧性、全球生产网络、金融地理、全球城市、不平等、企业家精神等成为新的研究热点。3）研究前沿具有较强的问题导向,主要基于西方发达国家的产业发展实践。4）研究空间呈现英美主导的两级格局,大部分国家仍处于边缘地带。5）国际经济地理学呈现明显的数字转向、可持续转型趋势,新冠疫情对学科走向也有一定影响。借鉴国际研究经验,中国经济地理学应加强理论创新并提出具有中国实践特色的理论体系,同时推动多学科之间的交叉融合并加强从社会学视角解读社会经济活动的地理学意义。     

A nonstationary parameter model for the sandstone creep tests

The rock masses of hydro-fluctuation belt experience seepage pressure following impoundment in the Three Gorges Reservoir; its creep behaviors are significant for reservoir bank slopes. To study the creep behaviors under seepage pressure (0, 1.45, and 1.75 MPa), we performed creep tests using representative landslide sandstone in the Three Gorges Reservoir and investigated the sandstone creep behaviors under the coupling effects of seepage pressure and stress. Previous researches on rocks have usually regarded the creep constitutive parameter as a constant; however, in this study, a nonlinear, nonstationary, plastic-viscous (NNPV) creep model which can describe the curve of sandstone creep tests is proposed. The rock-creep parameters under three levels of seepage pressure were identified, and theoretical curves using the NNPV model agreed well with the experimental data, indicating that the new model cannot only describe the primary creep and secondary creep stages under varying seepage pressures but also, in particular, perfectly describes the tertiary creep stage. Finally, the sensitivity of the NNPV model parameters is analyzed, and the result shows that the nonstationary coefficient α and the nonlinear coefficient m are main parameters affecting the tertiary creep stage.     

Effects of different soil and water conservation measures on hydrological extremes and flood processes in the Yanhe River,Loess Plateau,China

The runoff and sediment load of the Loess Plateau have changed significantly due to the implementation of soil and water conservation measures since the 1970s. However, the effects of soil and water conservation measures on hydrological extremes have rarely been considered. In this study, we investigated the variations in hydrological extremes and flood processes during different periods in the Yanhe River Basin (a tributary of the Loess Plateau) based on the daily mean runoff and 117 flood event data from 1956 to 2013. The study periods were divided into reference period (1956–1969), engineering measures period (1970–1995), and biological control measures period (1996–2013) according to the change points of the annual streamflow and the actual human activity in the basin. The results of the hydrological high extremes (HF1_max, HF3_max, HF7_max) exhibit a decreasing trend (P?<?0.01), whereas the hydrological low extremes (HBF1_min, HBF3_min, HBF7_min) show an increasing trend during 1956–2013. Compared with the hydrological extremes during the reference period, the hydrological high extremes increased during the engineering measures period at low (<?15%) and high frequency (>?80%), whereas decreased during the biological control measures period at almost all frequencies. The hydrological low extremes generally increased during both the engineering measures and biological control measures periods, particularly during the latter period. At the flood event scale, most flood event indices in connection with the runoff and sediment during the engineering measures period were significantly higher than those during the biological control measures period. The above results indicate that the ability to withstand hydrological extremes for the biological control measures was greater than that for the engineering measures in the studied basin. This work reveals the effects of different soil and water conservation measures on hydrological extremes in a typical basin of the Loess Plateau and hence can provide a useful reference for regional soil erosion control and disaster prevention policy-making.

     

某钼-铀矿床矿化特征及成因类型探讨

矿床产于中元古代地层中。矿区内酸性脉岩发育,常密集成带,矿床受穿过脉岩带的构造破碎带控制。矿化岩石主要为构造碎裂岩和角砾岩,其原岩为长英质脉岩、变石英砂岩、变安山岩、板岩及粉砂岩等。矿化以裂隙充填为主,对围岩化学成分的选择性不大。围岩蚀变有:绢云母化、硅化、钾长石化、黑云母化、黄铁矿化、赤铁矿化及水合多水高岭石化等。铀矿物主要为沥青铀矿、铀黑、铀石,其次有钛铀矿、水铀矾,含铀矿物有锐钛矿、金红石、赤铁矿、水合多水高岭石和褐铁矿等;其它金属矿物主要有辉钼矿、黄铁矿、方铅矿和黄铜矿。矿石具脉状、角砾状、块状和浸染状构造,沥青铀矿具胶状结构。矿床中钼的储量远大于铀,铀矿体产于钼矿体之中或其边部。通过室内、外研究,可以认为本矿床为与中酸性小侵入体有关的中-低温热液成因的钼-铀型复合矿床。     

中天山天湖东铁钼矿含矿片麻状花岗岩年代学、地球化学和锆石Hf同位素-对于中天山早古生代构造演化的启示

以中天山东段的天湖东铁钼矿含矿花岗岩为例,在LA-ICP-MS锆石U-Pb年代学测定其为早古生代花岗岩（（445.3±4.6） Ma）基础上,通过岩相学、地球化学及锆石原位Hf同位素组成等多方面研究,探讨该岩体的成岩作用及其构造背景。天湖东含矿片麻状花岗岩的主要矿物为斜长石、石英、钾长石,并含少量黑云母和角闪石等。全岩地球化学分析结果表明,该片麻状花岗岩高硅、弱富铝、富钙、富钠而贫钾,ASI值为0.68~0.82,属于准铝质钙碱性花岗岩,总体上富集大离子亲石元素（LILE）Rb、Ba等和轻稀土元素La、Ce、Nd等,而亏损高场强元素Nb、Ta、Ti、Yb等,轻重稀土分异明显,轻稀土分异较为明显,而重稀土分异不明显,表现出典型岛弧岩浆岩的地球化学特征。锆石的ε_Hf(445 Ma)值为-6.31~-1.77,二阶段Hf模式年龄（T_DM2）为1.538~1.825 Ga,表明该花岗岩的源区主要为壳源物质。综合分析上述资料,认为天湖东铁钼矿片麻状花岗岩是由俯冲过程中地壳物质重熔的产物。结合前人的研究和本课题组的新近研究成果认为,在早古生代时,中天山为岩浆弧构造环境,形成一系列的钙碱性岩浆岩,而该岩浆弧的形成可能是受到介于吐哈陆块和塔里木板块之间的古天山大洋在早古生代时期向南俯冲而形成的。     

朝鲜半岛古元古代摩天岭群的碎屑锆石U-Pb年龄及其地质意义

克拉通内部活动带变质沉积建造蕴藏了早期超大陆形成中地体聚-散动力学过程的重要信息,碎屑锆石年代学则是揭示这种信息的最佳工具之一。针对华北(中-朝)克拉通最具代表性的古元古代活动带(辽-吉-朝活动带)中巨量沉积建造精细表征方面的空白区域,本文开展了朝鲜半岛检德地区摩天岭群的碎屑锆石年代学研究。SIMS U-Pb定年结果显示,北大川组变火山碎屑岩样品的锆石年龄谱记录了约2.53Ga的主要年龄峰值和约2.19Ga的最年轻峰值,说明北大川组开始沉积的时代应该晚于2.2Ga。南大川组变沉积岩样品碎屑锆石记录的最年轻峰值年龄为约2.02Ga,说明南大川组的沉积时代应该不早于2.02Ga;其锆石年龄谱记录了一个主要年龄峰值区域(2.02~2.18Ga)、一个次要年龄峰值(约2.46Ga)和一些2.78~3.30 Ga的古老年龄,指示其物质源区主要为同区古元古代地质体和邻近地体上的太古宙变质基底。区域对比表明,摩天岭群与中国境内辽吉活动带中的辽河群及集安群/老岭群具有基本一致的碎屑锆石年龄谱,说明它们不仅是同一时代的产物,而且分享类似的物质源区。这些时代一致、物源相近的沉积建造可以为甄别古元古代辽-吉-朝活动带的大地构造属性提供重要参考。与沉积年龄相近的碎屑锆石占据主导的碎屑锆石年龄谱反映了汇聚板块边缘各类盆地的典型特征,而相悖于大部分碎屑锆石年龄远大于地层沉积年龄的裂谷型盆地。     

朝鲜半岛平南盆地中元古代岩浆事件

朝鲜平南盆地翁津地区发育中元古代黄海群和同时期(称之为瓮津期)花岗岩,花岗岩体侵入于黄海群。本文采用锆石原位微区U-Pb定年技术,对黄海群中的酸性火山岩及花岗岩进行了年龄测试。获得的数据表明,黄海群中下部层位及上部层位的酸性火山岩分别在1235±5Ma和1203±7Ma喷发,由此说明黄海群的沉积时代应为中元古代,而不是传统上认为的古元古代;两个翁津期花岗岩体(翁津和黄衣山岩体)的侵位年龄分别为1251±22Ma和1248±13Ma,为中元古代花岗质岩浆活动的产物。上述1251~1203Ma年龄的获得,表明朝鲜半岛发育中元古代岩浆作用,从而明确朝鲜黄海裂谷与华北东缘裂谷在时间上具有同期性,同时也表明中国华北与朝鲜在中元古代具有类似的发展历史。