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91.
青藏高原是全球气候变化影响的敏感区域。在全球气候变暖的背景下,其水文气候过程发生了显著的变化,直接影响到区域水资源演化。然而,目前对该区域水文气候过程的时空演变规律仍认识不足。本文以青藏高原气象站点降水观测数据为基准,结合水汽通量资料,对13种不同源降水数据集质量进行对比分析;并选用质量较好的IGSNRR数据集识别了青藏高原降水季节分配特征的空间分布格局。结果表明,青藏高原东南、西南以及西北边缘地区降水集中度和集中期较小,夏季降水占全年降水比例不足50%;随着逐渐向高原腹地推进,降水集中度和集中期逐渐增大,雨季逐渐缩短且推迟,雨季降水占全年降水比例逐渐增大。降水季节分配的空间分布格局与水汽运移方向保持一致,即主要是由西风和印度洋季风的影响所致。基于此,识别出西风的影响区域主要位于高原35°N以北,印度洋季风的影响区域主要位于高原约30°N以南,而高原中部(30°N~35°N)降水受到西风和印度洋季风的共同影响。该结果有助于进一步理解和认识青藏高原水文气候过程空间差异性。 相似文献
92.
新近沉积层是北京地区典型的浅部相对软弱土层,土层力学指标变异性较大.依据北京地区大量实际工程的勘察资料,采用土层分布随机场模型,对北京地区新近沉积典型地层的抗剪强度指标的空间概率特征进行统计分析,北京地区新近沉积土层的自相关距离一般为3~4 m,是比较合适的取样间距. 相似文献
93.
Based on instability theory and some former studies, the Simple Ocean Data Assimilation (SODA) data are analyzed to further study the difference between the propagation of the ENSO-related oceanic anomaly in the off-equatorial North Pacific Ocean before and after 1976. The investigation shows that after 1976 in the off-equatorial North Pacific Ocean, there is a larger area where the necessary conditions for baroclinic and/or barotropic instability are satisfied, which may help oceanic anomaly signals propagating in the form of Rossby waves to absorb energy from the mean currents so that they can grow and intensify. The baroclinic energy conversion rate in the North Pacific after 1976 is much higher than before 1976, which indicates that the baroclinic instability has intensified since 1976. Prom another perspective, the instability analysis gives an explanation of the phenomena that the ENSO-related oceanic anomaly signal in the North Pacific has intensified since 1976. 相似文献
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煤系岩石工程地质性质指标变异性研究 总被引:2,自引:0,他引:2
对山东金山矿区3煤覆岩及底板工程地质性质类型的物理力学性质指标的变异性进行了研究,用K-S法进行的概率分布类型拟合检验表明,各指标基本服从正态分布;另外,还对煤系岩石物理力学性质指标的关联性及各向异性特征进行了初步分析,为煤矿工程地质可靠度研究提供了依据。 相似文献
95.
Ya Luo Shengtian Yang Changsen Zhao Xiaoyan Liu Changming Liu Linna Wu Haigen Zhao Yichi Zhang 《地理学报(英文版)》2014,24(5):802-814
In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that: 1) Land use changed significantly in the period 1998-2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998.2) Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including (a) low-coverage grassland to medium-coverage grassland, (b) medium-coverage grassland to high-coverage grassland, (c) farmland to other woodland, and (d) farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3) The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relatively stable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China. 相似文献
96.
塔里木盆地北缘绿洲土壤含盐量和电导率空间变异性研究——以渭干河-库车河三角洲绿洲为例 总被引:7,自引:2,他引:7
土壤(及地下水)中水溶性盐的分析,是研究盐渍土盐分动态监测与预报技术的重要基础工作之一,对于及时掌握盐渍化程度与分布,合理制定土地利用政策与生态改良措施,实现区域可持续发展等方面具有重要作用.针对目前塔里木盆地北缘地区广泛存在的土壤盐渍化问题,基于GIS和地统计学方法,研究了渭-库绿洲盐渍化土壤特征(含盐量和电导率)的空间变异性.研究结果表明:渭-库绿洲表层土壤含盐量的空间依赖性比电导率强,表层土壤电导率和含盐量具有较强的空间相关性,变异强度中等,通过Moran's I系数分析,表明2个土壤特征均呈现一定强度的空间自相关关系,在此基础上做出了空间等值线分布趋势图,并进行了趋势分析.本研究为土壤特征变量空间变异分析与评价提供了普适性较强的实现方法,为构建盐渍土定量监测模型提供了一定科学依据. 相似文献
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