长江上游社会经济因子对侵蚀产沙的影响   总被引：1，自引：0，他引：1  

杜俊  师长兴  范小黎  周园园 《地理学报(英文版)》2011,21(2):359-371

In recent years,the role of human activities in changing sediment yield has become more apparent for the construction of hydraulic engineering and water conservation projec-tions in the Upper Yangtze River,but it has not been evaluated at the macro scale.Taking Sichuan Province and Chongqing City as an example,this paper studies the relationship between socio-economic factors and sediment yield in the Upper Yangtze River based on section data in 1989 and 2007.The results show that sediment yield is significantly correlated with population density and cultivated area,in which the former appears to be more closely related to sediment yield.Moreover,in the relation of sediment yield vs.population density,a critical value of population density exists,below which the sediment yield increases with the increase of population density and over which the sediment yield increases with the decrease of population density.The phenomenon essentially reflects the influence of natural factors,such as topography,precipitation and soil property,and some human activities on sediment yield.The region with a higher population density than critical value is located in the east of the study area and is characterized by plains,hills and low mountains,whereas the opposite is located in the west and characterized by middle and high mountains.In the eastern region,more people live on the lands with a low slope where regional soil erosion is slight;therefore,sediment yield is negatively related with population density.In contrast,in the western region,the population tends to aggregate in the areas with abundant soil and water resources which usually lead to a higher intensity of natural erosion,and in turn,high-intensity agricultural practices in these areas may further strengthen local soil erosion.It is also found that popu-lation tends to move from the areas with bad environment and high sediment yield to the areas with more comfortable environment and less sediment yield.The natural factors have greater influence on sediment yield of western region than that of eastern region.Generally,the natural factors play a dominant role on sediment yield in the Upper Yangtze River.  相似文献   

北极涛动对华北沙尘暴频次的影响   总被引：2，自引：0，他引：2  

毛睿  龚道溢  包景东  范一大 《地理学报(英文版)》2011,21(2):207-218

This study has investigated the influence of Arctic Oscillation (AO) on dust storm frequency in North China in spring seasons during 1961 2007.There is a significant linkage between dust storm frequency and AO;a negative (positive) AO phase is related to an in-creased (decreased) dust storm frequency in North China.This relationship is closely related to changes in the cold air activity in Mongolia.The cold air activity exerts large impacts on the dust storm frequency;the frequency of cold air activity over Mongolia not only positively cor-relates with the dust storm frequency in North China,but also shows a long-term decreasing trend that is an important reason for the long-term decreasing of dust storm frequency in North China.The AO has large influence on the frequency of cold air activity over Mongolia;a negative (positive) AO phase is highly related to an increased (decreased) frequency of cold air activity over Mongolia,which results in an increased (decreased) dust storm frequency in North China.  相似文献   

集合变分混合同化方案在快速循环同化系统中的应用研究     

张涵斌  李玉焕  陈敏  冯琎  范水勇  沈海波 《大气科学》2020,44(6):1349-1363

基于北京市气象局快速循环同化系统RMAPS-ST以及对流尺度集合预报系统RMAPS-EN,构建了En-3DVAR集合变分混合同化系统,将该系统应用到业务快速循环同化系统中并进行试验,分别在冷启动与循环启动环境下对比了混合同化系统（Hybrid）与三维变分（3DVAR）的同化预报效果。获得的结论如下:单点试验结果表明,混合同化系统分析增量的分布与集合预报离散度分布具有较好的对应关系;在冷启动和循环启动中,三维变分的分析增量都表现出各向同性的特点,混合同化分析增量均表现出一定的流依赖特征;降水个例分析表明,在冷启动环境中,Hybrid与3DVAR效果相当,而在循环启动中,Hybrid的降水预报相对于3DVAR有较明显的改进效果;批量试验检验结果表明,冷启动中,Hybrid与3DVAR的评分大致相当,而在循环启动中,Hybrid相对于3DVAR的评分有明显改进;集合离散度和背景场误差的相关性分析表明二者在循环启动环境下具有更好的相关性。  相似文献   

一次局地大暴雨过程中两个不同MCS成因分析     

钟敏  陈璇  王珊珊  范元月 《气象与环境科学》2020,43(4):28-37

  相似文献   

重大自然灾害空间信息协同服务机制研究     

范一大  王磊  李素菊 《遥感学报》2011,15(5):1053-1064

结合重大自然灾害应急管理的业务需求,分析了国外数据共享实践经验与案例,基于国家灾害管理实践工作经验,提出了中国建设重大自然灾害空间信息协同服务机制的构想。在进行职责任务划分的基础上,设立了包括指令中枢、数据中枢和信息中枢的立体化体制架构,并结合国家灾害管理业务工作的实际情况,制定了服务机制的业务关系流程,设定应急与常规相结合的运行模式,并对所需的保障配套机制进行了研究和分析。目前,重大自然灾害空间信息协同服务机制已经在国家灾害管理部门得到了一定范围的实践和检验,取得了较好的应用效果和社会经济效益。  相似文献   

德州市气象局一次网络故障分析及解决     

范佳林 《山东气象》2011,31(4):69-70

通过网络数据抓包软件对局域网中数据流的分析,对德州市气象局一次局域网网络拥堵现象进行研究分析,在首先分析局域网网络拓扑结构的基础上,判断问题的原因并找到解决问题的具体方法,快速恢复正常网络环境并做好系统日志记录。  相似文献   

构造成像中一类双曲型方程不适定问题的数值解法（Ⅱ）：逼近问题的适定…     

范尚武 《地球物理学报》1995,38(A01):31-38

地球物理中一类构造成像问题可以用双曲型偏微分方程不适定问题来描述，这时表征地质构造的地下反射波场由这类不适定问题的解来表示。作者已撰文讨论了这类不适定问题的提法并提出了数值求解这类基本问题的逼近问题。  相似文献   

当代油气勘探发展趋势：非地震多参数油气资源预测     

范兴业  刘茂强 《世界地质》1995,14(2):69-76

西文从油气勘探的发展简史及现状入手，在详细介绍非地震多参数油气资源预测方法和应用实例的基础之上，阐明了此方法较好的经济效益、社会效益以及周期短的优点，通过与常规油气勘探对比，表明其必将成为当代油气勘探的趋势。  相似文献   

当代油气勘探发展趋势─—非地震多参数油气资源预测     

范兴业  刘茂强  杨丙中  单玄龙 《世界地质》1995,(2)

本文从油气勘探的发展简史及现状人手，在详细介绍非地震多参数油气资源预测方法和应用实例的基础之上，阐明了此方法较好的经济效益、社会效益以及周期短的优点，通过与常规油气勘探对比，表明其必将成为当代油气勘探的趋势。  相似文献   

东北北部夏季旱涝形成机理的数值研究   总被引：2，自引：2，他引：2  

邹立尧  王咏青  马镜娴  张立  范水勇 《南京气象学院学报》2001,24(1):127-136

根据 1 95 8～ 1 996年黑龙江省 38个代表站历年降水量资料和同期北半球 2 .5°× 2 .5°格点 5 0 0 h Pa位势高度资料 ,分别求出了干旱和洪涝年份 7、8月的流型 ,指出东北北部盛夏旱涝的形成与东亚由冬至夏的季节转换联系密切。用北半球正压模式实施 4组积分时间为 30个模式日的数值试验 ,成功地模拟了 7、8月干旱和洪涝流型的形成和持续过程 ,并分析了与旱涝流型相应的热源强迫场的不同特征  相似文献