高原低涡移出高原的观测事实分析

应用天气学、统计学原理,结合TRMM资料,分析了1998—2004年5—9月移出高原的低涡的活动特征。结果指出:6—8月是高原低涡移出高原影响中国东部天气的主要时段,它与高原低涡在高原上的活动特征及西南低涡移出高原特征均不同;移出高原的高原低涡的涡源主要在曲麻莱附近、德格附近,这与高原上产生低涡的涡源不同;移出高原的高原低涡的移动路径多数是随低槽的活动而向东、向东南移动,这与高原低涡在高原上多数是沿切变线移向东北不同,高原低涡移出高原后,不仅影响中国的范围广,还可能影响到朝鲜半岛、日本;高原低涡移出高原后涡的强度、性质会有变化,在高原以东活动时间长(≥36 h)的高原低涡,移出高原前多数为暖性低涡,移出高原后多数为斜压性低涡,低涡加强、多数可产生暴雨、大暴雨;高原低涡移出高原后移到海洋上,往往因下垫面不同而变化,出海后都有降水加强、多数位势高度下降的现象;移出高原后的高原低涡因东面海上热带气旋活动而少动,与其南面热带气旋活动相向而行,因季风低压少动而少动的现象。     

历史时期中国重大自然灾害时空分异特征(英文)

Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the hazard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China.     

On the timing of the East Asian summer monsoon maximum during the Holocene—Does the speleothem oxygen isotope record reflect monsoon rainfall variability?

The evolution of the East Asian summer monsoon(EASM) during the Holocene has long been of significant interest.Knowledge of past EASM variability not only increases our understanding of monsoon dynamics on a long timescale,but it also provides an environmental and climatic background for research into Chinese cultural development.However,the timing of the EASM maximum remains controversial.The popular concept of an "early Holocene maximum" is mainly based on speleothemδ~(18)O(δ~(18)O_c) records from caves in southern China;however,the interpretation of δ~(18)O_C as a reliable proxy for EASM intensity is being increasingly challenged.The present paper is a critical review of the climatic significance of the δ~(18)O_C record from China.Firstly,we suggest that precipitation in northern China is an appropriate index of EASM intensity,the variation of which clearly indicates a mid-Holocene monsoon maximum.Secondly,an interregional comparison demonstrates that the precipitation record in northern China is quite different from that in southern China on a range of timescales,and is inconsistent with the spatial similarity exhibited by speleothem oxygen isotope records.Furthermore,both modeling and observational data show that the δ~(18)O_C records from southern China indeed reflect changes in precipitation δ~(18)O(δ~(18)O_P) rather than precipitation amount,and therefore that their use as an EASM proxy is inappropriate.Finally,we address several significant monsoon-related issues-including the driving mechanism of the EASM on an orbital timescale,the climatic significance of speleothem oxygen isotopes,and the relationship between atmospheric circulation and precipitation in monsoonal regions.     

湖北恩施地区土壤-植物系统中Se元素的 地球化学特征

在对恩施地区典型农业活动区——芭蕉、长平和鱼塘坝三地土壤中Se元素含量进行调查的基础上,通过与富Se土壤质量标准进行对比,发现除长平地区外,其余两地分别属于富Se和高Se地区,并通过土壤理化性质、形态分析和土壤中所生长的植物进行比较,初步研究了Se在土壤-植物体系中迁移转化的规律。结果表明：整体来看,鱼塘坝地区属于超富Se地区,植物中Se的含量也最高,长平地区属于非富Se地区,芭蕉地区则属于中等富Se地区;植物对Se的吸收受一定的土壤理化性质的影响,不同类型的植物对Se的吸收富集相差较大;形态分析研究表明,鱼塘坝地区土壤中生物可利用的Se含量较高,而芭蕉地区土壤中残渣态Se的比例较高,表现为Se的生物可利用性低于鱼塘坝地区。     

塔里木盆地巴楚—麦盖提地区石炭系混合沉积研究*

通过岩心、薄片观察,从岩石学特征入手,结合测井资料,对塔里木盆地巴楚—麦盖提地区石炭系的陆源碎屑—碳酸盐混积岩和混积层系进行了研究。根据混积强度将混积岩划分为混积型碎屑岩、混积型碳酸盐岩和高度混积岩。巴楚组下泥岩段和中泥岩段发育混积型碎屑岩,巴楚组生屑灰岩段、中泥岩段和小海子组发育混积型碳酸盐岩,卡拉沙依组上泥岩段、巴楚组下泥岩段及巴什托局部地区的中泥岩段发育高度混积岩。高度混积岩出现在海退期沉积的碎屑岩段,代表了陆源碎屑—碳酸盐强烈混合的过渡性沉积环境。研究区石炭系可识别出4个三级层序,混积层系主要发育在海侵体系域早期和高位体系域晚期,以间断混合和相缘混合为主。研究认为混积强度是评价混合沉积环境性质的主要参数,并将其划分为4级。下泥岩段存在混积强度达3级以上的混积界面,能用于地层对比。最后,结合混合沉积特征讨论了构造运动和海平面变化对研究区石炭系层序组以上的混合沉积的控制作用。     

西准噶尔达尔布特蛇绿岩带萨尔托海岩体深部结构、构造特征:地质与地球物理证据

西准噶尔地区分布多条蛇绿混杂岩带,地表地质已有大量研究成果,但蛇绿岩深部结构构造研究相对薄弱,一定程度上制约了该地区地质构造演化的深入认识.为此,本文选取达尔布特蛇绿混杂岩带萨尔托海段开展了大比例尺地质填图配套地面重力、磁法和可控源音频大地电磁测深(CSAMT)等综合测量,获得了该蛇绿岩体地表分布、接触关系以及深部的磁性、密度结构和电性特征,精细刻画了蛇绿岩的深部结构与构造,并进一步分析了其侵位机制和动力学过程.萨尔托海蛇绿岩具有低重力、高磁性和变化范围较宽的电阻率值,岩体整体以构造岩块状产出,表现出挤压逆冲、走滑剪切、破碎蚀变等变形变质.本文及前人研究成果表明,萨尔托海岩体是在近东西向挤压兼走滑应力作用下以斜向楔冲形式构造就位,并进一步受到后期左行走滑和岩浆作用的叠加改造.结合区域构造演化,西准噶尔蛇绿岩的构造侵位与晚石炭世板块汇聚背景下残余洋盆的收缩有关,持续的挤压兼走滑应力使残余洋盆下伏基底蛇绿岩沿断裂构造侵位于上覆沉积地层.     

Energy spectra and relative abundances of ions of C,O, and Fe at 1 AU during the quiet sun

The ion composition of fluxes of charged particles in interplanetary space with energies ∼0.03–10 MeV/nucleon are studied during quiet periods in the 23rd solar-activity cycle using data from the ACE spacecraft. Apart from the activity minimum, the Fe/O ratio during such periods corresponds to either the relative abundances of ions in particle fluxes accelerated in solar flares or the mean abundances of elements in the solar corona. At the cycle minimum, this ratio takes on values characteristic for the solar wind. These results indicate that the background fluxes of low-energy particles in the phases of the growth, maximum, and decay of the solar cycle include significant contributions from both coronal particles accelerated to suprathermal energies and particles accelerated in small impulsive solar flares. The particle fluxes from such flares are distinguished by an enhanced abundance of iron ions.     

粘结式锚杆在爆炸动载下轴向应力分布研究

通过物理模型试验,研究在爆炸动载作用下临近工作面支护锚杆的应力状态。根据相似条件和简化假设,采用集中装药进行工程掏槽爆破模拟,利用粘贴在锚杆上的应变片测得近区端锚和全锚锚杆的轴向应变波。测试结果表明,爆破引起锚杆振动时间约为6 ms,经过9 ms的缓降期锚杆变形趋于稳定值;动载期间端锚锚杆在杆体中部锚固段测得峰值应力比杆体尾部自由段的值大,但相差不大,动载过后尾部的残余应力较大;全锚锚杆在杆体尾部测得的峰值应力和残余应力都远大于杆体中部测得值。利用无限体内一点受法向集中力作用的位移势函数,推导锚固体及周围岩体的轴向应力分布,并计算一定预应力在锚固区产生的附加轴向应力,结合动应力的作用分析锚杆的受力状态     

边界层过程对"98·7"长江流域暴雨预报影响的数值试验研究

通过ETA模式对"98@7"长江流域暴雨过程的数值试验研究,讨论了行星边界层过程对暴雨数值预报的影响,结果表明边界层过程在这次暴雨预报中有重要作用.具体结论为:(1)降水大范围落区是受大尺度流场所决定的,但边界层过程对暴雨预报具有重要的作用;(2)不考虑边界层过程会影响对天气系统的正确预报,包括影响大气低层的运动场、水汽及大气不稳定度,从而影响暴雨的预报;(3)从时间层次上看,由于地表通量有着显著的日变化,边界层过程的作用不仅与暴雨本身发生发展及消亡的阶段有关,也与各阶段的时间(白天或夜间)有联系;(4)在空间范围内,边界层过程对大气的影响是通过大气流场重新分布来影响降水的环境条件,故地表通量分布和低层流场的相互配置作用十分重要.长江南北的情况有所不同,长江流域南侧区是地表通量的大值区,也是长江流域雨区水汽和不稳定能量的源区,它对长江流域的暴雨可能有着更为重要的作用.