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131.
Subsurface old drainage detection and paleoenvironment analysis using spaceborne radar images in Alxa Plateau 总被引:2,自引:0,他引:2
For geological and environmental research in an arid area, a unique advantage of radar remote sensing is that radar wave can penetrate a certain layer of dry sand (a few centimeters to meters thick) to reach the buried bedrock. The penetration capability is able to reveal the subsurface geological structure and old drainage paths. Based on the analysis of SIR-A, SIR-B, SIR-C, Radarsat ScanSAR, Landsat MSS and Landsat TM images acquired on different dates and the investigations made in several field trips in Alxa Plateau of Inner Mongolia, a number of old river valley and lake basins buried by wind-blown sand were recognized. Two parallel old drainage systems in the north and middle of the study area are delineated. The study suggests that the moving sand belts mainly follow the old drainage courses. This study also establishes a preliminary drainage evolution model for an area of about 300 000 km2 since the Tertiary, and finds that the Alxa Plateau was once an area with many rivers and lakes with a warm and humid climate. The relief reversion caused by neotectonic movement since "Qinghai-Tibet movement" is also analyzed. 相似文献
132.
This paper proposes a rain considered geophysical model function (GMF), to be noted as GMF plus Rain. GMF plus Rain is based on the basic raidative transfer model with attenuation and scattering effects of rain on radar signal considered. Combined with the NSCAT2 GMF and the rain correction model, the GMF plus Rain model is used to retrieve the ocean wind vectors from the collocated QuikSCAT and SSM/I rain rate data for typhoon Melor. The resulting wind speed estimates of typhoon Melor show improved agreement with the wind fields derived from the best track analysis of Japan Meteorological Agency (JMA). The results imply that compared with the GMF model, the GMF plus Rain model can improve the precision of wind retrieval under the rain condition. Then, a new general algorithm of locating the eye of typhoon through the normalized radar cross section (NRCS) is proposed. The implementation of this algorithm in the ten QuikSCAT observations of typhoon Melor suggests that this algorithm is effective. 相似文献
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134.
基于嫦娥一号数字高程模型(DEM)数据,利用地形信息参数来描述月表撞击坑的边缘轮廓特征,采用Hough变换检测方法提取了月表撞击坑。将该方法应用于克拉维乌斯(Klavius)撞击坑的周围区域,在DEM数据500 m空间分辨率下,不考虑退化严重的撞击坑时,检测百分比D=90%,分支系数B=0.30,质量百分比Q=71%,在考虑退化严重的撞击坑时,D=71%,B=0.30,Q=58%;研究表明该算法对没有退化或轻微退化的撞击坑有很好检测效果。与基于影像数据月表撞击坑自动检测的研究进行比较,本文给出的算法具有更高的检测精度,同时虚假检测较少。证明该方法用于月表撞击坑的自动检测是可行的。 相似文献
135.
海洋沉积物中氧化亚铁的分析测定 总被引:2,自引:0,他引:2
海洋沉积物试样用H2O2-HAc浸取,用以除去干扰测定FeO的锰化合物和硫化珠,并以H2SO3-Na2SO3混合溶液破坏过乘的H2O2,不需过滤分离,即可用HF-H2SO4分解试样,K2Cr2O7标准溶液滴定FeO。方法经海洋沉积物国家标准物质分析验证,结果与参考值相符,RSD为6.33%。 相似文献
136.
利用NCEP/NCAR再分析资料、Hadley中心海温资料及CMAP降水资料等,通过亚澳季风联合指数挑选异常年份,对东亚夏季风和澳洲冬季风强度反相变化特征进行研究。结果表明,当东亚夏季风偏强、澳洲冬季风偏弱时,南北半球中低纬地区都出现了复杂的异常环流系统。在热带地区对流层低层,西北太平洋为异常反气旋式环流系统所控制,与南太平洋赤道辐合带的异常反气旋环流在赤道地区发生耦合,形成赤道异常东风,而在南北印度洋上则存在两个异常气旋式环流系统。在这两对异常环流之间的海洋性大陆地区,出现赤道以南为反气旋环流而赤道以北为气旋式环流。在东亚季风区,东南沿海的东侧海洋上存在反气旋异常,中国东南地区受异常反气旋西南侧的东南风影响。此外,澳洲北部受异常西风影响。这就形成了东亚夏季风偏强、澳洲冬季风偏弱的情形,从而东亚夏季风和澳洲冬季风活动出现了强弱互补的变化特征。当东亚夏季风偏弱、澳洲冬季风偏强时,南北半球的环流特征则出现与上述相反的环流特征。总体而言,当东亚夏季风偏强、澳洲冬季风偏弱时,东亚—澳洲季风区在南北半球呈现出不同的气候异常分布特征,即北半球降水北少南多、气温北高南低,南半球降水西多东少、气温西高东低。 相似文献
137.
Repeating airgun sources are eco-friendly sources for monitoring the changes in the physical properties of subsurface mediums, but their signals decay quickly and are buried in the noises soon after traveling short distances. Stacking waveforms from different airgun shots recorded by a single seismic station (shot stacking) is the most popular technique to detect weak signals from noisy backgrounds, and has been widely used to process the data of Fixed Airgun Signal Transmission Stations (FASTS) in China. However, shot stacking sacrifices the time resolution in monitoring to recover a qualified airgun signal by stacking many shots at distance stations, and also suffers from persistent local noises. In this paper, we carried out several small-aperture seismic array experiments around the Binchuan FAST Station (BCFASTS) in Yunnan Province,China, and applied the array technique to improve airgun signal detection. The results show that seismic array processing combining with shot stacking can suppress seismic noises more efficiently, and provide better signal-to-noise ratio (SNR) and coherent airgun signals with less airgun shots. This work suggests that the array technique is a feasible and promising tool in FAST to increase the time resolution and reduce noise interference on routine monitoring. 相似文献
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139.
塔里木盆地塔中Ⅰ号构造带在构造样式、活动强度等方面表现出明显的分段性,但分段变形的运动学特征与成因仍不够明确,需要开展进一步研究。本文利用二维、三维地震资料,通过精细构造解析、运动学参数统计、活动期次厘定等手段,研究了塔中Ⅰ号构造带的几何学、运动学特征,分析其分段变形机制,并讨论了分段控制因素。研究表明:以中古15井与中古21井位置为界,塔中Ⅰ号构造带构造样式、运动学特征主要呈三段的特点,西段主要活动机制是断裂短距离滑动逆冲和地层旋转变形,同一层位的落差/垂直断距(H/h)值最大;中段为断裂沿走向滑动,H/h值约为1;东段为断裂长距离滑动逆冲和强烈褶皱,H/h值介于二者之间。活动机制的差异导致各段构造样式分别为基底卷入逆冲断裂控制的断层传播褶皱、走滑断裂发育的断控坡折、逆冲断裂强烈活动控制的断块褶皱,且活动强度呈现东段最大、西段次之、中段较小的特点。两大造山带分期活动是塔中Ⅰ号构造带分段变形的发育背景,基底结构与先存断裂是造成分段的主控因素,NE向走滑断裂调节塔中Ⅰ号构造带差异逆冲变形,并作为伴生断裂发育。 相似文献
140.