Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion   总被引：3，自引：0，他引：3  

Maria Wik  Ingemar Renberg 《Journal of Paleolimnology》1996,15(3):193-206

Analysis of fly-ash particles in lake sediments has become increasingly important in studies of environmental pollution and lake acidification history. Most fly-ash studies have concerned black spheroidal carbonaceous particles (SCP)(>5 m) produced from oil and coal combustion. This review paper provides a summary of this technique and its application, and focusses on our investigations in Sweden between 1979 and 1993. It consists of five parts: i) preparation and analysis methods, ii) historical trends in atmospheric deposition, iii) geographical surveys of atmospheric deposition, iv) sediment dating, and v) studies of sedimentation processes in lakes. Methods for preparation and analyses of SCP have been developed and applied to investigations using sediment, soil and snow samples. Stratigraphic trends of SCP concentrations in lake-sediment cores reflect the consumption history of fossil fuels. A characteristic temporal SCP pattern, with a marked concentration increase beginning after the 1940's and a peak in the early 1970's, has been recognized in most Swedish lakes and elsewhere in Europe. A survey of SCP concentrations in surface sediments of >100 lakes covering Sweden demonstrated that polluted areas in southern Sweden had >100 times higher SCP concentrations than clean areas in the north. The spatial distribution of SCP over Sweden is similar to the deposition pattern of long-range transported airborne pollutants, such as excess sulphate monitored by network stations. SCP also accumulate in soils, and soil analyses can be used for determining the integrated historical deposition of SCP at the local or regional scale. Finally, SCP have been used for indirect dating of sediment cores and as a marker to assess sediment distribution patterns within lake basins.  相似文献   

Avalanche Risk During Backcountry Skiing – An Analysis of Risk Factors     

Harpa Grímsdóttir  David Mcclung 《Natural Hazards》2006,39(1):127-153

Skier-triggered avalanches are the main cause of avalanche accidents in backcountry skiing. The risk of accidents during backcountry skiing was analysed statistically and related to factors such as elevation level, aspect, stability rating and the time of the year. The analysis is based on a database about terrain usage and avalanche accidents from a large heli-skiing operator in Canada, which makes it possible to study the conditional probability of accidents given the recorded pattern of terrain usage. This study shows that the historical risk of accidentally triggering an avalanche greater than size 1 depends highly on the stability rating, with the highest risk occurring during “poor” stability. The risk is greater at high elevations, and it is lower during the late season than earlier on. Skier risk does not depend as much on aspect as may be indicated from avalanche data alone. However, it is relatively high in the N–NE–E sector. These factors are not independent of each other and therefore analyses of combined factors were also performed. Questionnaires and interviews were used to gain knowledge about the terrain selection of professional mountain guides. These results indicate that when selecting terrain, guides first look at the overall shape and size of the terrain, but avalanche history of terrain and inclination are also important factors. Finally, remarks in avalanche reports were analysed, and common human factors identified.  相似文献   

极地冰雪氢氧同位素指标及其指示意义   总被引：1，自引：0，他引：1       下载免费PDF全文

张小伟  康建成  周尚哲 《极地研究》2002,14(1):73-80

本文综述了水汽来源状况、降水季节变化、火山喷发、太阳活动等气候环境因素对极地冰雪中同位素含量的可能影响及其程度 ,以及降水区域不均衡性、降水年际不均衡性、逆温层和同位素在冰雪中的扩散迁移作用等几种不稳定因素可能对冰雪同位素分析造成的干扰 ;在此基础上 ,综述了极地冰雪中δ1 8O、δD和其差值d(d =δD - 8δ1 8O)与局部或全球气温之间的一些线性关系 (包括全球尺度 ,格陵兰地区 ,南极地区等 )及它们在空间分布上的变化规律  相似文献   

渭干河流域"2002·7"特大洪水分析   总被引：6，自引：0，他引：6  

黄健  毛炜峄  李燕  王顺德 《冰川冻土》2003,25(2):204-210

渭干河是塔里木河流域第六大源流, 位于天山西部南麓, 渭干河干流起点有新疆最大的流域性控制工程--克孜尔水库. 2002年7月下旬天山中西部山区出现大暴雨(雪)过程, 渭干河流域山区降水持续时间长达30 h以上, 山区降水量50 mm左右, 导致5条支流和渭干河干流出现有水文记录以来的最大洪峰, 流量超过警戒流量和危险流量的2～3.5倍, 暴雨(雪)过程结束之后, 融雪型洪峰长时间居高不下. 洪水过程中, 各支流以及暴雨与融雪等多种洪峰遭遇现象很明显. 克孜尔水库入库洪峰流量达3 660 m3*s-1, 经水库调洪错峰, 出库峰值流量为1 000 m3*s-1, 削峰率72.7%.  相似文献   

南通地区暴雪的天气条件对比分析   总被引：11，自引：0，他引：11  

陈佩君  徐云 《气象》2003,29(12):45-47

通过对20世纪50年代以来南通地区的四次暴雪过程的分析，试从环流形势的配置、强度及物理量场特征上，找出具有共性的暴雪的指标，以供预报参考。  相似文献   

南京"2003.2.10"寒潮降温降雨(雪)天气过程初步分析     

苏晓燕  张贵明  徐卫丽 《山西气象》2003,(3):5-7,11

对2003年2月10日至11日发生在南京的一次寒潮降温降雨(雪)的主要影响系统，如阻塞高压、高空槽、横槽、中低层暖式切变线、地面冷锋以及地面暖低压倒槽等进行了描述和分析，并对某些物理量进行了分析。分析得出：这次寒潮降温降雨(雪)天气是在高空500hPa乌拉尔山阻塞高压崩溃、巴尔喀什湖至准噶尔盆地的横槽转竖，冷空气从西北路径东移南下，中低层冷槽与暖式切变线接合以及地面冷锋切入暖低压倒槽等天气系统的作用下发生的，并归纳出此类天气预报的指示系统，对于做好寒潮天气预报具有指导作用。  相似文献   

一次降雪过程的中尺度模式(MM5)站点预报试验     

高俊寿  崔建国  梁清萍  蔡广丽 《山西气象》2003,(4):11-12,18

本文利用中尺度数值预报模式(MM5)进行业务预报试验。对2002年12月6日前后一次降水过程进行应用分析，重点对阳泉市站点预报进行对比检验，得出该模式在站点有无降雪、降雪量级及降雪起报、结束时间等方面具有重要参考价值的结论，对于进一步开发降水预报精细产品有重要意义。  相似文献   

青藏高原冬季积雪异常对东,南亚夏季风影响的初步数值模拟研究   总被引：10，自引：2，他引：10  

范广洲  罗四维 《高原气象》1997,16(2):140-142

利用一个耦合了简化的简单生物圈模式的大气环流谱模式（ＳＳｉＢ－ＧＣＭ），初步探讨了青藏高原冬季积雪异常对东、南亚夏季季风环流和降水的影响及其机理。结果表明，高原地区积雪增加将使随后地夏季东、南来季风明显减弱，主要表现为东、南亚季风区降水减少，索马里急流、印度季风的印度西南气流弱弱。另外，还提出欧亚大陆雪盖与整个高原雪盖和高原东部雪盖对东、南亚夏季风影响的敏感问题。与欧亚大陆雪盖相比，高原雪盖是影响  相似文献   

人工增雪对冬麦冻害的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

高子毅  贾昭茂 《气象》1997,23(9):27-30

自１９７８年以来，在新疆北部沿天山一带对冬季层状云飞机播撒碘化银、干冰等冷云催化剂进行人工增雪作业，对１８个非播云年和１７个播云年的冬麦冻害做了对比，在播云期内冬小麦年平均冻害面积减少８０％以上。对３个主要因素（麦种改良、冬季气温升高和人工增雪）进行了分析，结果表明，人工播云是一个主要的因素。  相似文献   

气球携带碘化银焰弹技术研究   总被引：1，自引：1，他引：1       下载免费PDF全文

秦长学 《气象》1997,23(11):11-13

主要介绍在北京地区开展气球携带碘化银焰弹雨雪作业的作业技术，经济效益等问题。通过各种增雨雪技术比较，认敢球携带碘化银焰弹增雨雪作业在北方干旱地区的抗旱工作中或作为收音机增雨雪作业的补充手段具有应用价值  相似文献