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The influence of the elastic Earth properties on seasonal or shorter periodic surface deformations due to atmospheric surface pressure and terrestrial water storage variations is usually modeled by applying a local half-space model or an one dimensional spherical Earth model like PREM from which a unique set of elastic load Love numbers, or alternatively, elastic Green's functions are derived. The first model is valid only if load and observer almost coincide, the second model considers only the response of an average Earth structure. However, for surface loads with horizontal scales less than 2500 km2, as for instance, for strong localized hydrological signals associated with heavy precipitation events and river floods, the Earth elastic response becomes very sensitive to inhomogeneities in the Earth crustal structure.We derive a set of local Green's functions defined globally on a 1° × 1° grid for the 3-layer crustal structure TEA12. Local Green's functions show standard deviations of ±12% in the vertical and ±21% in the horizontal directions for distances in the range from 0.1° to 0.5°. By means of Green's function scatter plots, we analyze the dependence of the load response to various crustal rocks and layer thicknesses. The application of local Green's functions instead of a mean global Green's function introduces a variability of 0.5–1.0 mm into the hydrological loading displacements, both in vertical and in horizontal directions. Maximum changes due to the local crustal structures are from −25% to +26% in the vertical and −91% to +55% in the horizontal displacements. In addition, the horizontal displacement can change its direction significantly. The lateral deviations in surface deformation due to local crustal elastic properties are found to be much larger than the differences between various commonly used one-dimensional Earth models. 相似文献
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东昆仑造山带东段哈图沟–清水泉–沟里韧性剪切带塑性变形及动力学条件研究 总被引：1，自引：0，他引：1
东昆仑造山带东段哈图沟–清水泉–沟里韧性剪切带记录了多个旋回的造山作用,本文通过对韧性剪切带中石英c轴组构和显微构造特征测试分析,探讨东昆仑造山带东段陆块间俯冲拼合及地壳伸展减薄的形成机制。结果显示,韧性剪切带变形温度介于380~650℃之间,形成环境为中–高绿片岩相到低角闪岩相,剪切带内差异应力值介于173~509 MPa之间,应变速率介于6.93×10–14~1.43×10–8 s–1之间,主体为10–11~10–10 s–1,显示韧性剪切带变形是快速俯冲作用下的产物,越靠近东昆仑造山带东段东昆中断裂带其变形温度、差异应力值及相应的应变速率值越大,表明东昆仑造山带东段韧性剪切变形中心为东昆中断裂带。利用不同方法所计算出的韧性剪切带运动学涡度值,显示韧性剪切带早期瞬时运动学涡度(0.56~1)对应于东昆仑造山带东段东昆南与东昆仑造山带东段东昆北陆块间俯冲的初始阶段,中后期运动学涡度(0.25~0.91)应当对应于东昆南与东昆北陆块间的俯冲碰撞阶段,最晚期的C′瞬时运动学涡度(0.19~0.51)则对应于后造山的伸展阶段。通过石英c轴组构结合其宏微观构造特征,认为东昆中构造带至少经历了3个期次的构造运动,分别为加里东晚期的逆冲兼左行走滑剪切作用、晚海西–印支期的逆冲兼右行走滑剪切作用和燕山早期及之后的脆韧性–脆性的左行走滑剪切作用。 相似文献
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讨论了新一代（多普勒）天气雷达对2002年5月14日19:00至21:00影响湖南常德地区的3个对流风暴的探测情况,其中两个为超级单体,一个为飑线。观测到了与超级单体相联系的中气旋和龙卷式涡旋特征（TVS）。上述强对流系统产生了地面大风、大冰雹和龙卷等强烈天气,与雷达的探测相吻合。特别值得一提的是在中国首次探测到了三体散射（TBSS）和龙卷式涡旋特征（TVS）这两个分别指示大冰雹和龙卷的雷达回波特征,并得到了地面报告的印证。 相似文献
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地震勘探方法在深部固体矿产资源勘探中发展潜力巨大,同时也面临挑战.由于固体矿产资源地下分布呈现陡峭构造、尺度小,物性差异小的特点,常规偏移方法对小尺度矿体成像的分辨率提高有限.本文研究了一种基于稀疏促进约束的最小二乘逆时偏移方法.首先,将非均匀分布的矿体等效为随机介质,建立小尺度扰动的矿体模型;其次,改进现有最小二乘偏移方法,以稀疏模型为先验信息约束成像结果,并通过Curvelet变换压缩成像空间,经过多次迭代计算,可以提高小尺度散射体的成像分辨率;再次,对炮域记录进行随机震源编码,减少成像所需的炮集个数,通过稀疏促进约束条件,降低串扰噪声引起的成像误差.通过庐枞金属矿模型数值计算,验证本文方法可以较好的成像包含小尺度散射体的金属矿地质模型.
相似文献5.
利用NOAA卫星AVHRR资料分析云的性质 总被引：13，自引：0，他引：13
文章利用NOAA卫星AVHRR的通道3（3.55～3.93 μm）、通道4（10.3～11.3 μm）和通道5（11.5～12.5 μm）所在波长上的亮温（BT3,BT4,BT5）以及它们之间的亮温差（BTD34,BTD45）,分析云的性质。分析表明:对于密蔽的云和无云区,通道间亮温差有极小值,在密实的云区BTD34可出现负值;当存在半透明云时,通道间亮温差大;云与背景地面之间温差点聚图的振幅越大,通道间亮温差越大。 相似文献
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本文选用2018年12月至2019年12月共计32景Sentinel-1升轨影像数据,基于PSI技术对贵阳市进行了形变信息提取.结果显示,监测区内共发现较大形变区24处,其中沉降区21处,抬升区3处.通过统计学方法,证明了地铁沿线并无明显形变,对形变区进行分析发现,24处形变区均与城市化建设有关,与地铁施工运行并无关系... 相似文献
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Ch. Venkateswara Rao K.M.M. Rao P. Shasidhar Reddy Girish Pujar 《International Journal of Applied Earth Observation and Geoinformation》2008,10(2):165-1
The Resourcesat-I satellite is equipped with different types of sensors with varied characteristics. For the effective utilization of the available multi-sensor, multi-temporal, multi-spectral and multi-radiometric data from these sensors, fusion of digital image data has become a valuable technique. Image fusion enhances the information content and helps in better discrimination of various land cover types. The Resourcesat-1 has equipped with three sensors, AWiFS, LISS-III and LISS-IV, which are having identical spectral resolutions, with different spatial, radiometric and temporal resolutions. The spatial resolutions ratio of the data set for merging are required to be maximum of 1:6, where as the data sets (AWiFS and LISS-III) that are used in the current study are having the ratio of 1:2.5 approximately. A novel merging technique is designed, which retains the multi-spectral response of the input data in the output data. The merged data set provides the higher spatial and radiometric resolutions. In order to evaluate the fusion merits quantitatively, all the data sets are digitally classified and studied the output classes for homogeneity and clear discrimination. A comprehensive comparative study is carried out between the fused image and the LISS-III image based on the contingency matrix and the scatter plots, which demonstrates the strength of fused image for discriminating the object classes at 23.5 m spatial and 10-bit radiometric resolutions. The merged data set gives the improved classification accuracy. 相似文献
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本文尝试结合非相干散射雷达和GPS TEC观测数据提取等离子体层总电子含量(PTEC).我们首先描述所用的技术方法,然后具体利用了Millstone Hill台站的观测数据研究该地区上空等离子体层总电子含量(PTEC)的变化情况.我们采用变化标高的Chapman函数对非相干散射雷达测得的电子浓度剖面数据进行拟合,然后通过对剖面积分得到100 km到1000 km高度范围的电离层总电子含量.GPS提供的TEC数据为高度达20200 km的总电子含量,两者之差可近似看成等离子体层的电子含量.本文分别选取太阳活动高年(2000, 2002年)和太阳活动低年(2005,2008年)Millstone Hill台站的静日数据进行研究.结果表明,等离子体层电子含量及其所占GPS TEC的比例具有明显的周日变化.PTEC含量在白天高于夜间,而所占GPS TEC的百分比,夜间明显高于白天.太阳活动高年所选月份等离子体层电子含量在4~14 TECU (1TECU=1016el/m2) 范围内变化,夜间所占比例可达60%左右.太阳活动低年所选月份等离子体层电子含量在3~7 TECU范围内变化,所占比例夜间最高可达80%左右.我们所得到的结果与前人基于其它观测手段所得结果在变化趋势上一致,在量级上也大致相当.因此,这从一个侧面证明了我们所用方法的可靠性.非相干散射雷达能够探测包括F2层峰值以下及以上高度的电子浓度,利用这一设备所观测得到的资料来推算电离层电子含量将比前人基于电离层垂测仪观测资料进行的推算更具真实性,由此得到的等离子体层电子含量也将更为接近真实情况. 相似文献
