Aircraft observations of electrical conductivity in warm clouds

Aircraft observations of electrical conductivity and cloud microphsical, dynamical and other electrical parameters were made in warm stratocumulus and cumulus clouds forming during the summer monsoon seasons (June-September) of 1983 and 1985 in the Deccan Plateau region, India. A Gerdien type cylindrical condenser was used for the measurement of electrical conductivity. The variations in the electrical conductivity are observed to be closely associated with the updrafts and downdrafts in the cloud, liquid water content, cloud droplet charge and coro-na discharge current. The value of electrical conductivity in warm clouds is found to be in the order of 10-12 ohm-1 m-1 which is two orders higher than that observed in clear-air at cloud-base levels in some regions by other investigators.Classical static electricity concepts predict reduced conductivity values inside clouds. Cloud electrical conductivi-ty measurements, particularly in warm clouds are few and the results are contradictory. The recently identified mech-anism of vertical mixing in clouds lends support to coovective charge separation mechanism with inherent larger than clear-air values for cloud electrical conductivity and therefore consistent with the measurements reported herein.     

在预警系统中识别多重事件的贝叶斯方法

2011年日本东北地震（MW9.0）发生之后出现了大量余震,使得在主震后的第一个月内发布了70次预警信息。在这些警报中,有不可忽视的部分（63%）都是虚报,其中最大的预期地震烈度被高估了至少两个烈度或更大。这些错误大部分可归因于多个同时发生的余震,而这些余震通常发生在主震之后较短时间及较长距离内。基于考虑在任何给定时间内出现一个以上事件几率的贝叶斯公式,我们提出了一种适用于区分多个同时发生地震的新颖似然函数,其中使用的是振幅信息。同时,我们还使用了序贯蒙特卡罗探试法,这种方法的复杂性随事件个数呈线性增长关系。我们还进一步实施了质点滤波,并用东北地震后的余震记录在经验上验证了其性能。初步的实例研究表明,这个方法在对发生时间相近的多个地震事件进行区分时能达到预期的效果。     

中国陆台的构造及其发展

作者本文中叙述了中国陆台自前武纪至中生代与新生代期间的发展,根据该区地质历史的基础,作者提出关于中国陆台的界限及陆台内部大山脉构造之新的见解。中国陆台实质上最近才认出的亚洲大陆上的一个新的构造单元,至今在地质学文献中还末经阐明。中国地质家在其本国疆域内认出四块不大的地盾构造:山     

塞浦路斯特罗多斯型洋壳最上部500米剖面(CY—1钻孔)中的不透明矿物、磁性及其蚀变作用的研究

引 言 近十年来为了鉴别大洋盆地中线性磁异常模式的起源,对洋壳磁化强度的研究显示了极大的兴趣。目前了解洋壳(尤其在深部)可以通过几种方法,如在推测为构造断崖的附近进行海底拖曳打捞、通过大洋基底钻探或通过考察蛇绿岩剖面等。 拖曳打捞和钻探均可从原地洋壳的各个层位获得样品,但是在钻探大洋基底时,大多数钻孔的穿透小于100米,一些深孔也小于600米,这个深度与推测的洋壳喷出岩1.5     

太古宙地壳基底的铀富集与上冲断层

在巴西巴伊亚州卡蒂特(Caetite)东北部的拉戈阿罗尔(Lagoa Roal)地区,堆积U_3O_8100,000公吨的铀矿床,产在横切太古宙基底片麻岩的韧性剪切带中。片麻岩的年龄为26亿—30亿年,变质相为角闪岩相到麻粒岩相。一般认为这种岩石形成在接近地壳基底的地方。比起上地壳,其铀的亏损特别明显。在拉戈阿罗尔的东部和西     

前寒武纪大气圈的氧和条带状铁建造:一种延滞海洋模式

序言由于新的证据不断地积累,日益明显,支持地球早期大气圈存在自由氧的论点必须给予认真考虑。对自由氧是否存在的争论比较少了。然而,这种氧的含量水平及其供应来源则成了注意的焦点。在地球历史的最早期就存在氧的光解作用,在氧的光合作用出现以前,要求人们重新考虑有关生命起源及其早期演化的条件。在这种情况下,作为原始有机物质来源于大气     

Forms of Iron in the Phosphorites of Abu—Tartur Area,Egypt

The Campanian-Maastrichtian phosphatic deposits in Egypt,called the Duwi Forma-tion,comprise a part of the extensive Middle East to North African phosphogenic province of Late Cretaceous to Paleogene age.The province holds the greatest accumulation of phosphorites in the geological history,possibly in excess of 70 billion metric tons.The phosphate resources in Egypt alone exceed 3 billion metric tons.Two-third of these three billions occur only in the Abu-Tartur area.Among the phosphorite deposits in Egypt,the phosphorites of the Abu-Tartur area are characterized by high contents of iron ranging from 3% to 7% with an average of 5%.The detailed mineralogical and geochemical studies on the Abu-Tartur phosphorites revealed that iron is found in the form of pyrite,ankerite,clay minerals,microinclusions,and iron oxide.Pyrite,which is the major fraction,occurs as filling cement and partial to complete teplacement of phosphatic grains and confined to the fresh phosphorites while iron oxide occurs as cryp-tocrystalline aggregates of red to brown particles and is confined to the weathered outcrops.Ex-clusive relations between pyrite in the fresh phosphorite samples inside the Abu-Tartur mine and iron oxide in the equivalent horizon of the weathered exposure indicated that iron oxide was formed by the oxidation of pyrite as a result of weathering.All of these forms harm the quality of ore,manufacturing processes,and the produced phosphoric acid and fertilizers.