基于VAD技术的迭代法在实测多普勒速度缺测区域的填补研究

多普勒天气雷达径向速度场缺测区域的存在是影响速度二次产品算法精确度的重要因素,在实际风场为线性分布的假设条件下,文中详细介绍了一种基于VAD技术的迭代填补技术.在合理考虑迭代约束条件的情况下,应用实测多普勒速度数据,根据缺测区域类型随机制造非连续累积10°-180°缺口的缺测区域和连续累积10°-180°缺口的缺测区域...     

电线积冰物理过程与数值模拟研究进展

电线积冰对人们的日常生活、电力系统、通信系统等造成了巨大的影响,人们越来越关注电线积冰的形成条件及物理过程,包括气象条件、气流动力学、液滴运动轨迹以及热力学过程。通过外场观测、室内实验和数值模拟研究的不断开展,揭示出电线积冰质量增长过程决定于云降水粒子谱分布、碰撞效率、黏性率、冻结率、碰撞速度和角度等微物理参数,这些参数又受控于降水率、云雾含水量、温度、湿度、风向、风速等宏观气象条件。通过数值模式已可进行电线积冰量和积冰持续时间的定量研究和预测,进而在开发垂冰模式和形态模式等方面也取得了新的进展。在总结过去60多年来电线积冰物理机制和数值模拟研究主要成果的基础上,对开展进一步的深入研究进行了展望。     

淮北地区一次连续性暴雨的成因分析

利用各种常规资料,分析了2005年7月7-10日发生在淮北大面积连续暴雨、大暴雨天气过程的环流背景、发生机制及成因.本次大面积连续性暴雨的天气形势为两槽一脊型,旺盛的水汽在冷空气促发下形成了强烈的上升运动,中低层有很强的切变和暖湿平流,从而不断生成中尺度对流云团.此次移动性暴雨过程的前期由不断向东移动发展的MCS造成,后期降水则由低涡切变线产生的中尺度低涡引起.冷空气不断补充南下,副高西伸至淮河以南地区,冷暖空气在淮北地区交汇,且切变线稳定少动,是此次连续性强降水产生的主要因素.     

基于MODIS资料的贵州植被叶面积指数的时空变化及其对气候的响应

利用2000～2006年MODIS(Moderate Resolution Imaging Spectroradiometer)卫星遥感观测的植被叶面积指数月平均资料以及相应时段的月平均气温、降水的观测资料对贵州植被的时空变化进行了分析.结果表明贵州2000～2006年植被分布受水热条件控制表现出对气候因子不同的响应关系,其中对降水的响应关系比气温明显,特别是冬季和春季,而植被在夏季和秋季的分布主要受气温的制约,与降水的关系并不明显.从季节和年际尺度的时间变化角度而言,植被对气温的响应比对降水明显,季节变化和年际变化的相关系数分别为0.89和0.73(分别通过99.9%和95%信度检验).     

气象条件对高速公路路面抗滑性能影响的试验

对高速公路路面抗滑性能与温度、路面状况及使用融雪剂等不同条件的关系进行测试和分析,测试在实验室条件下和实际路面上分别进行。测试及分析结果表明:路面抗滑性能因气温和路面状况不同而有很大差异,尤其是冬季的冰雪和低温天气,对路面抗滑性能的不利影响最为显著。此外,气象条件与路面实际抗滑性能的关系还与其标准抗滑性能有关。     

Integration of InVEST-habitat quality model with landscape pattern indexes to assess mountain plant biodiversity change: A case study of Bailongjiang watershed in Gansu Province

Journal of Geographical Sciences - Mountains in western China, hosted rich biodiversity and millions of people and inhabitant with vital ecosystem services, had experienced the most serious...     

Barchans of Minqin: Morphometry

The barchans on the border of Minqin oasis, China, were surveyed. Our data reconfirmed that the height of slipface is proportional to the width of horns and the baseline can be roughly described by parts of an ellipse and a parabola. We attempted to study dune geomorphology using the theory of differential geometry. The geometrical characteristics of the brink can be quantitatively determined by its curvature and torsion.     

合肥盆地钻井地层的同位素测年与地层划分

合肥盆地内部中、新界地层大面积被第四系覆盖，其地层的时代与划分主要依赖已有的6口深井地层资料。由于缺乏可靠的化石记录，这6口深井地层时代与划分一直存在着很大的分歧，制约了对该盆地的油气勘探与远景评价。本文利用这6口深井泥岩类岩屑中自生伊利石，在其结晶度分析基础上，进行了K-Ar同位素测年，成功地获得了不同深度上的地层形成时代。据此地层年龄，文中对这6口深井所钻遇的地层进行了重新的划分。     

Land degradation in the source region of the Yellow River, northeast Qinghai-Xizang Plateau: classification and evaluation

Land degradation imposes a great threat to the world. It is not merely an environmental issue, but also a social and economic problem. Land desertification is among the main aspects of environment changes in the source region of the Yellow River. Previous studies focused on water resource utilization and soil erosion, but land degradation in the source region of the Yellow River even the whole Qinghai-Xizang Plateau received little attention. Based on the data obtained by field investigation and TM satellite images of 2000, this study provides the classification and evaluation information of the land degradation in the source region of the Yellow River. There are six types of land degradation in this region: water erosion in the northern mountains around the Gonghe Basin, sandy desertification in the Gonghe Basin and Upland Plain Area, aridization in the lower reaches, salinization in the Gonghe Basin, vegetation degradation in the intramontance basin and freezing and thawing erosion in the high mountains. The total degraded area is 34,429.6 km², making up 37.5% of the land in the study area. Finally, land degradation in the source region of the Yellow River was evaluated according to changes in the physical structure and chemical component of soils, land productivity, secondary soil salt and water conditions.     

A Review on the Global Stratotype Section and Point of the Permian-Triassic Boundary

1 Introduction The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary (PTB) has been ratified by IUGS in 2001 (Yin et al., 2001). It is defined at the base of the Hindeodus parvus horizon, i.e. the base of Bed 27c of Meishan Section D, Changxing County, Zhejiang Province, South China. The PTB is important because it is not only an erathem boundary but also a great turning point of geological history symbolized by profound global changes and the strongest …