Projection of drought hazards in China during twenty-first century

Theoretical and Applied Climatology - Drought is occurring with increased frequency under climate warming. To understand the behavior of drought and its variation in the future, current and future...     

Sinkhole hazard assessment in Minnesota using a decision tree model

An understanding of what influences sinkhole formation and the ability to accurately predict sinkhole hazards is critical to environmental management efforts in the karst lands of southeastern Minnesota. Based on the distribution of distances to the nearest sinkhole, sinkhole density, bedrock geology and depth to bedrock in southeastern Minnesota and northwestern Iowa, a decision tree model has been developed to construct maps of sinkhole probability in Minnesota. The decision tree model was converted as cartographic models and implemented in ArcGIS to create a preliminary sinkhole probability map in Goodhue, Wabasha, Olmsted, Fillmore, and Mower Counties. This model quantifies bedrock geology, depth to bedrock, sinkhole density, and neighborhood effects in southeastern Minnesota but excludes potential controlling factors such as structural control, topographic settings, human activities and land-use. The sinkhole probability map needs to be verified and updated as more sinkholes are mapped and more information about sinkhole formation is obtained.     

Spatial operations in a GIS-based karst feature database

This paper presents the spatial implementation of the karst feature database (KFD) of Minnesota in a GIS environment. ESRI’s ArcInfo and ArcView GIS packages were used to analyze and manipulate the spatial operations of the KFD of Minnesota. Spatial operations were classified into three data manipulation categories: single layer operation, multiple layer operation, and other spatial transformation in the KFD. Most of the spatial operations discussed in this paper can be conducted using ArcInfo, ArcView, and ArcGIS. A set of strategies and rules were proposed and used to build the spatial operational module in the KFD to make the spatial operations more efficient and topographically correct.     

M—γ尺度G—Chen坐标系中气候模式的研制（续完）

（上接本刊 2000年第 4期第 30页） 4土壤系统模式的建立及其参数化 　　覆盖地球陆地表面较薄的土壤覆盖物是一种性质变化很大的多孔物质。它的固相是由岩石风化成的无机物和伴有栖居于土壤的动植物有机产物所组成。这些物质的质地范围可从粗砂到细粘土，构成土壤层的物质随土壤剖面上下位置的不同而有很大区别。太原地区的土壤大致为壤土 (轻粘土 )，为讨论处理方便起见，我们略去了土质上下层之间的微小变化。 　　下面我们建立描述土壤热量和水分交换的运动方程，大气和土壤的质能交换主要是通过这两种过程实现…     

云南地区强震前中小地震活跃—平静的定量计算

以累计频度定量计算方法 ,讨论了云南地区 1970年以来 ,各个强震孕震区的地震活动非线性度ZL值的时间进程曲线 ,系统计算了Ms≥ 6 3级强震前的ZL值曲线 ,结果表明 :强震前地震活动非线性度ZL值异常表现出的地震孕震区的地震平静—活跃或活跃—平静过程至少出现一次 ,且震例中的 83 %开始出现平静(活跃 )的时间为强震前 1～ 2 12 年 ,强震前半年左右结束出现活跃 (平静 )。     

压缩恢复法在井间层析成像中的应用

本文将“压缩恢复法”应用到钻孔电磁波勘探中,并通过建立两个数字化图像模型予以计算机实现。与非压缩法比较,可以看出“压缩恢复法”有一定效果。     

初探地震活动的时间分维特征

本文运用分维的概念和方法,对我国部分强震前地震活动时间分维,前震震群活动时间分维,7级以上大地震的余震活动时间分维和小震群活动时间分维进行了计算。初步结果表明,同一类型的地震活动(如强震前较大时空范围内地震活动、强震的余震、前震震群、小震群等类型)的时间分维十分相近,而不同类型地震活动的时间分维存在着差异,一般说来,强震前的地震活动比较普遍地存在降维现象,表现出临近强震时,震源及附近地区地震活动时间结构的有序性增强。这为地震预报开辟了一个新的途径。     

胶东两大成因系列金矿石英包裹体氢氧同位素及成矿流体组分地球化学研究

胶东金的成矿作用是在以前寒武纪绿岩带为初始矿源层背景上演化的。与各时代地质热事件相匹配的成矿作用形成了区域两大内生成因系列热液金矿——元古宙变生热液金矿及中生代大气降水热液金矿。成矿流体与围岩相互作用过程中的δD、δ~(18)O演化规律及成矿流体化学组分一方面揭示了这两种矿床成因的差异,另一方面又反映了它们存在着某些内在的成因联系。     

Characteristics and possible formation mechanisms of severe storms in the outer rainbands of Typhoon Mujiga (1522)

To better understand how severe storms form and evolve in the outer rainbands of typhoons, in this study, we investigate the evolutionary characteristics and possible formation mechanisms for severe storms in the rainbands of Typhoon Mujigae, which occurred during 2–5 October 2015, based on the NCEP–NCAR reanalysis data, conventional observations, and Doppler radar data. For the rainbands far from the inner core (eye and eyewall) of Mujigae (distance of approximately 70–800 km), wind speed first increased with the radius expanding from the inner core, and then decreased as the radius continued to expand. The Rankine Vortex Model was used to explore such variations in wind speed. The areas of strong stormy rainbands were mainly located in the northeast quadrant of Mujigae, and overlapped with the areas of high winds within approximately 300–550 km away from the inner core, where the strong winds were conducive to the development of strong storms. A severe convective cell in the rainbands developed into waterspout at approximately 500 km to the northeast of the inner core, when Mujigae was strengthening before it made landfall. Two severe convective cells in the rainbands developed into two tornadoes at approximately 350 km to the northeast of the inner core after Mujigae made landfall. The radar echo bands enhanced to 60 dBZ when mesocyclones occurred in the rainbands and induced tornadoes. The radar echoes gradually weakened after the mesocyclones weakened. The tops of parent clouds of the mesocyclones elevated at first, and then suddenly dropped about 20 min before the tornadoes appeared. Thereby, the cloud top variation has the potential to be used as an early warning of tornado occurrence.