公元1000—2000年中国北方地区极端干旱事件序列重建与分析

利用历史文献记录重建了公元1000—2000年中国北方地区极端干旱事件序列,在此基础上分析极端干旱事件的发生特征与规律。研究得出以下结论:(1)极端干旱事件在公元1000—2000年中存在200年左右的周期波动。在15世纪中期、17世纪初期和18世纪末期存在3次极端干旱事件高发期。(2)极端干旱事件的变动与中国东部地区干湿变化相一致,在偏干的时期极端干旱事件发生次数上升,在偏湿时则下降。(3)在中世纪暖期和现代暖期,温度愈高,极端干旱事件偏多;而在小冰期,则温度偏低的时期极端干旱事件多发。(4)西风带影响下的非季风区,干湿变化与极端干旱事件的关系与华北季风区相反,这可能与所谓的“丝绸之路遥相关”和NAO(NorthAtlanticOscillation,北大西洋涛动)的影响有关。     

环境磁学及其在地理环境研究中的应用

环境磁学兴起于20世纪70年代，是一门介于地球科学、环境科学和磁学之间的边缘学科。其原理是测量土壤、岩石和沉积物等自然物质和人类活动产生的物质在人为磁场中的磁性响应，提取地理环境的信息。由于系统磁性测量技术本身的优点，高灵敏度测试仪器，以及计算机处理磁测数据，使环境磁学广泛应用于湖泊及流域古地理研究、土壤形成和分类、黄土－古土壤研究和环境污染研究等许多研究领域。近年来环境磁学有一些新的发展趋势。     

JFSAS04.##2对海南万宁降水预报的统计分析

通过对 jfsas0 4.# # 2的预报质量统计 ,从而了解它在什么时候的预报效果较佳 ,在什么时候不够理想 ,有利于提高预报准确率。     

1998年7月21～22日特大暴雨过程的中-β尺度云团特征

文中以气象卫星云图为主，分析了１９９８年７月２１～２２日由于副热带高压减弱南移，长江中下 游地区再次出现大范围暴雨过程的天气系统特征，发现：①暴雨是由 两个中-β尺度云团造成的，中-β尺度云团是发生在两个中尺度云团之间的积云区中 ，均在清晨发生，午后减弱，其生命史约为１０　ｈ左右；②云团发生在低层水汽与能量条件较 好的区域和８５０～７００　ｈＰａ低涡切变上，这里有较强的地转偏差存在，并位于６．７　μｍ水汽图 上干湿区交界的湿区一侧的环境中。     

大坝变形监测遗传神经网络模型

在简要介绍遗传神经网络的基本概念及学习步骤的基础上,分别对大坝坝顶径向水平位移、切向水平位移和大坝坝顶沉降量监测数据进行了训练和预测。结果表明,利用遗传算法特有的全局优化能力,可以较好地完成网络的学习,而且还减少了网络训练次数,缩短了网络训练时间。     

The impact of geophysical parameters on longwave radiation budget at the top and base of the atmosphere

Summary The effect of clouds on longwave radiation budget at the top and base of the atmosphere is studied by using the HIRS2/MSU-retrieved temperature and humidity fields, and cloud fields and the International Satellite Cloud Climatology Project-produced fields. Detailed studies are carried out at four selected sites: one at Equatorial Eastern Pacific (ITCZ) area, one at Libyan Desert (Libya), one at Ottawa, Montreal (Ottawa), and one at central Europe (Europe). The monthly mean differences in outgoing longwave radiation (OLR) (the ISCCP-based OLR minus the HIRS2-based OLR), ranging from –2.8 Wm^–2 at ITCZ to –15.4 Wm^–2 at Ottawa, are less than the monthly mean differences in surface downward flux, ranging from –2.7 Wm^–2 at Libya to 40.6 Wm^–2 at the ITCZ. The large differences in surface downward flux are mainly due to large differences in cloud amount and moisture in the low levels of the atmosphere.Monthly mean OLR and surface downward flux can be derived either (1) from instantaneous temperature, humidity, and cloud fields over a month period or (2) from monthly mean temperature, humidity, and cloud fields. The monthly mean OLR and surface downward flux derived from the first approach is compared with the second. The differences in OLR are small, ranging from –0.05 Wm^–2 to 6.2 Wm^–2, and the differences in surface downward flux is also small, ranging from 0.4 Wm^–2 to 6.4 Wm^–2.List of Acronyms AVHRR Advanced Very High Resolution radiometer - ERB Earth Radiation Budget - ERBE Earth Radiation Budget Experiment - FGGE First Global GARP Experiment - GARP Global Atmospheric Research Program - GCM General Circulation Model - GISS Goddard Institute for Space Studies - GLA Goddard Laboratory for Atmospheres - GMS Geostationary Meteorological Satellite - GOES Geostationary Operational Environmental Satellite - HIRS2 High Resolution Infrared Radiation Sounder/2 - ISCCP International Satellite Cloud Climatology Project - IR Infrared - MSU Microwave Sounding Unit - NFOV Narrow Field of View - NOAA National Oceanic and Atmospheric Administration - NESDIS National Environmental Satellite Data Information Service - TOVS TIROS Operational Vertical Sounder With 4 Figures     

阿尔金走滑断裂带昌马段的电性结构样式及构造意义

阿尔金断裂带东段走滑速率沿断裂走向方向存在明显的流失现象,有关阿尔金断裂带的影响范围及走滑速率变化的机制需要有更多的深部结构证据来提供支撑.本文以阿尔金断裂带昌马段为窗口,获取了4条横穿阿尔金断裂带及相邻地区的大地电磁测深剖面.二维电性剖面显示在阿尔金断裂带北侧中上地壳以连续的高阻体为主,而南侧祁连山内部的深部电性结构在横向上有较为复杂的变化.这一点与区域构造背景相对应,即北侧的塔里木盆地东缘依然具有较好的整体性,南侧的祁连山是青藏高原北缘生长的最前端,变形强烈.在断裂带的结构特征上,阿尔金断裂带沿走向方向的切割深度在昌马盆地西侧发生了显著的降低,与阿尔金断裂带相对应的电性边界在这里向南偏移了约15 km,对应F18断裂,并与昌马盆地相接.祁连山北部的断裂带,包括昌马断裂、旱峡—大黄沟断裂总体呈现出低角度南倾的样式,切过高阻异常体的顶部.虽然昌马盆地可以起到连接断裂带的阶区的作用,将部分阿尔金断裂的走滑分量转移到盆地南侧的昌马断裂上,但是昌马断裂的走滑速率从西向东是增加的,东侧的走滑速率甚至大于阿尔金断裂沿走向方向的流失分量.我们认为在青藏高原北部主要断裂带的活动还是受印度—欧亚板块碰撞引起的远程挤压效应的影响,包括阿尔金断裂以及祁连山内部系列断层都处于斜向挤压应力环境.在这种基本构造模式下,阿尔金断裂、断裂F18、昌马盆地、昌马断裂构成了一个局部的走滑速率分解-转换-吸收体系,对局部应力状态产生影响.     

Effects of ultrasonic cleaning on the amino acid geochemistry of foraminifera tests

Although investigations into amino acid geochemistry of foraminifera have included the use of ultrasonic cleaners as part of their cleaning procedure, there apparently has been no attempt to determine what effects this procedure may have on the observed chemical changes. This paper presents the results of a time study showing the effects of cleaning on ten protein amino acids and the non-protein alloisoleucine. The data suggest that there are three loosely defined groups which all ultimately undergo an exponential decrease in concentration, but which vary within the initial 45 min of treatment: Group I, stable; Group II, constantly decreasing; Group III, showing slight increases. The observed effects suggest that studies based on amino acid enantiomeric ratios probably are the least affected by procedural errors introduced by ultrasonification.     

陕西旬阳地区志留系铅锌矿矿集区特征及其成因初探

通过十多年的勘查及研究，在陕西旬阳—白河一带的志留系中新发现了大型铅锌矿矿集区。该矿集区东西长约100km，南北宽10—50km。区内有中志留统双河镇组和下志留统梅子垭组两个含矿层位及泗人沟—南沙沟、红土坡—韩氏沟—小沟、西营—黄石板三个成矿带。在成矿带内已发现20余处铅锌(铜)矿床(点)，资源丰富，找矿潜力较大。该矿床成因为细碎屑岩沉积—改造型铅锌矿床。