共查询到19条相似文献，搜索用时 113 毫秒
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利用层析成像方法反演近地表速度模型 总被引：1，自引：0，他引：1
由于地表条件复杂和近地表速度变化显著给近地表速度模型的反演工作带来了很大的困难。层析成像方法可以较好地模拟介质横向和纵向的速度变化,能同时考虑直达波、透射波、回折波、折射波等初至波,为确定近地表速度结构提供了有效的工具。主要介绍了层析成像的方法原理,并应用此方法反演了实际地震探区的近地表速度模型,取得了良好的应用效果。 相似文献
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针对鄂尔多斯盆地南部黄土塬区复杂地表条件下的直测线二维地震资料进行了处理攻关试验,通过近地表模型静校正、折射波静校正和层析静校正等方法的对比试验,提出了更适应本地区的静校正方法。并且通过振幅补偿、叠前去噪等技术方法改善了资料品质,提高了资料的信噪比和分辨率,可为进一步落实和发现局部构造及勘探开发部署提供重要的依据。 相似文献
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巨厚砾石区表层结构调查方法研究 总被引：1，自引：0，他引：1
随着勘探程度的加深，对资料精度的要求越来越高。袁层结构调查的准确与否，直接影响资料的可靠程度如何，常规的表层结构调查方法已无法满足复杂地表勘探的需要。准噶尔盆地边缘地表形态主要以巨厚砾石区为主，通过对巨厚砾石区低降速带调查方法的研究、实践，最终确定采用小折射追踪加大炮初至解释法和深井微测井控制法，较好地解决了巨厚砾石区的低降速带调查问题，为后续的资料处理提供了精确的静校正数据，为以后该地表类型的施工及表层结构研究提供了依据。 相似文献
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黄河农场地区地下水入海通量的数值分析 总被引：4，自引：0，他引：4
在系统地调查和分析了黄河三角洲地区自然地理、地质和水文地质条件的基础上，进行了不同的水文地质试验和地下水长期观测，并尝试建立黄河三角洲典型地段－黄河农场地区的水文地质数学模型，定量分析该地区地下水入海量的变化规律及不同因素的影响程度。研究结果表明，当地的气象因素和黄河、小岛河及海洋的水位都不同程度地影响地下水的入海量，而且黄河的水位变化和气象因素是影响黄河三角洲地区地下水入海量的主要因素。另外，黄河三角洲地区地下水的入海量比地表径流入海量小得多。 相似文献
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利用2007—2010年间存档的30景Envisat ASAR数据,运用SBAS技术对黄河三角洲地区地面沉降进行全面具体监测,获取黄河三角洲地区地表形变特征场,分析了典型沉降区形变时间序列特征,结合相关资料对三角洲地区地面沉降影响因素进行了分析。研究表明,人类活动(地下水抽取、油气开采与工程建筑等)是造成地面沉降的主要因素,油田区地表形变范围与断层存在一定相关性。 相似文献
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利用Landsat TM6反演地表温度所需地表辐射率参数的估计方法 总被引：18，自引：0，他引：18
地表温度是地球资源环境动态分析的重要指标.从热红外遥感数据中反演地表温度通常需要地表比辐射率为已知.因此,地表比辐射率的估计是地表温度遥感反演的关键.陆地卫星Landsat TM有一个热波段(TM6),可以用来反演地表温度.目前共有3种算法可以用来从TM6波段数据中反演地表温度大气校正法、单窗算法和单通道算法.这3种算法都需要TM6波段范围内的地表发射率来作为地表温度反演的参数.首先简介这3种反演算法,然后重点探讨TM6的地表发射率估计方法.TM6的星下空间分辨率为120 m.在这一尺度上,大多数情况下天然地表的构成可以看成是由水面、植被和裸土三种基本类型构成.城镇像元也可看成是由建筑表面和绿化植物构成.根据这几种地表类型的地表发射率相对较稳定的特性,提出了用TM数据的可见光波段来进行TM6像元的地表发射率的估计.TM3和TM4波段可以用来确定植被叶冠在像元尺度上的覆盖度.通过这一覆盖度,就可以构建混合像元的地表热辐射构成方程,以便进行地表发射率的简单估计,从而为TM6热波段数据在农业和资源环境监测中的广泛应用,提供技术支撑.最后,用这一方法来进行华北平原山东省陵县地区的地表发射率估计和地表温度反演.分析表明,这一方法能获得较合理的地表温度反演结果. 相似文献
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《中国海洋大学学报(自然科学版)》2021,(9)
传统的走时层析方法依赖于初始速度模型,需要射线追踪计算,速度建模效率低。常规的回折波走时反演方法速度建模效率较高,但通过对走时曲线拟合获取射线参数,受地形起伏和走时误差的影响很大,速度建模精度较低。为兼顾近地表速度建模的效率与精度,本文改进了回折波走时方程,提出一种基于回折波走时方程的起伏地表速度建模方法。该方法将每一个共中心点道集按偏移距大小进行选排并分段,在每一个偏移距段内,先利用回折波走时方程逐道计算相应的回折点位置和速度,再对各个炮检对的计算结果进行最小二乘拟合及反距离加权,获得统计平均回折点位置和速度值。对每个共中心点道集均做上述处理,从而建立近地表速度模型。理论模型测试和实测资料应用验证了本文方法的正确性和实用性。 相似文献
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V. G. Trifonov 《Izvestiya Atmospheric and Oceanic Physics》2011,47(9):995-1006
The main achievements and development trends of geological investigations with the use of space facilities during the last
30 years are analyzed, including the study of the structure of the near-surface Earth crustal layer and deep lithosphere,
quest for mineral deposits, and prediction of natural hazards and effects of recent geological processes. It is shown that
some methods and techniques transformed into routine geological operations with the progress in facilities of space data acquisition
and processing, while new opportunities and techniques were successful. The results of space-geological investigations that
have promoted solution of important geological tasks are presented. 相似文献
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The solar radiation coming to the Earth’s ellipsoid is considered without taking into account the atmosphere on the basis of the astronomical ephemerides for the time interval from 3000 BC to 3000 AD. Using the regression equations between the Earth’s insolation and near-surface air temperature, the insolation annual and semiannual climatic norms of near-surface air temperature for the Earth as a whole and the hemispheres are calculated in intervals of 30 years for the period from 2930 BC to 2930 AD with 100 and 900- to 1000-year time steps. The analysis shows that the annual insolation rates of the near-surface air temperature of the Earth and the hemispheres decrease at all intervals. The semiannual insolation rates of the near-surface air temperature increase in winter and decrease in summer. This means that the seasonal difference decreases. The annual and semiannual rates of insolation near-surface air temperature of the Earth increase in the equatorial and decrease in the polar regions; the latitudinal contrast increases. The interlatitudinal gradient is higher in the Southern Hemisphere. It practically does not change in winter and increases in summer, most strongly in the Southern Hemisphere. 相似文献
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R.R. Rao M.S. Girish Kumar M. Ravichandran V.V. Gopalakrishna P. Thadathil 《Deep Sea Research Part I: Oceanographic Research Papers》2008,55(8):1009-1020
During winter, south of the Indo-Sri Lanka Channel (ISLC), the observed sea-surface temperature (SST) distribution shows a distinct mini-cold pool (MCP) with relatively cooler waters (SST<28 °C). All the available satellite and in-situ measurements are utilized to characterize and explain the mechanisms that govern the evolution of the observed MCP. During December–January, the northeasterly surface winds blow through the ISLC manifesting a patch of strong winds in the south with peak intensity of about 10 m/s, enhance surface turbulent heat losses and drive near-surface vertical mixing resulting in the observed cooling. The vertical temperature profiles in this region also show cooling and deepening of the near-surface isothermal layer from November to January. This cooling occurs episodically on an intra-seasonal time scale with a typical periodicity of 8–15 days and is stronger when the surface winds intensify, surface net heat losses are larger and the near-surface circulation is more pronounced. The cooling episodes varied in number, intensity, duration and spatial extent in each winter during 1998–2006. The cooler surface waters from this MCP flow initially southwestward and are then topographically steered northwestward by the Maldives Island Chain. The resultant near-surface circulation also appears to strengthen the amplitude of the near-surface thermal inversions observed in the SouthEastern Arabian Sea (SEAS). 相似文献
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利用渤海湾北岸祥云岛岸基站2017—2018年观测数据和两座梯度测风塔2011—2013年观测资料分别分析了当地海陆风和湍流强度特征,并重点对不同天气系统所致大风条件下的湍流强度特点做了剖析。结果表明:渤海湾北岸海陆风特征明显,昼夜风向主要由SSW向ENE转变,夏季昼夜风向转换尤为显著。整体而言,风速和湍流强度随高度增大分别呈增大、减小趋势,且近海面层湍流强度小于近地层湍流强度。湍流强度具有显著的季节性特征,夏季大、冬季小、春秋季变化不明显,且近海面层湍流强度相对近地层变化平缓。近海面层70 m及以下湍流强度在偏东大风条件下反而比近地层湍流强度大,雷雨大风期间近海面层和近地层均出现湍流强度随高度增大而增大、风速随高度增大而减小的特殊情况,台风靠近风塔时各层风速显著增大、湍流强度变化不明显,但台风中心到达时湍流强度迅速增至峰值,二者时间一致并早于风速最小值出现时间约1 h。近海面层和近地层有8%～10%样本的湍流强度超出了IEC-61400设计标准,建议渤海湾北岸风力发电风机抗湍流参数调整至0. 43～0. 49。 相似文献
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An acoustic current meter attached to a servo-hydraulic surface-following device was used to obtain near-surface velocity measurements beneath breaking and near breaking surface gravity waves shoaling on a 1:40 beach. The data are compared to velocities predicted by two adaptations of linear theory: superposition and stretching. For unbroken and near breaking waves, the predictions are in close agreement with the measurements. For breaking and broken waves, near surface crest velocity measurements are influenced by air entrainment; trough velocities are relatively well predicted. The problems associated with the acoustic measurement of near-surface velocities are highlighted. 相似文献
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在南海北部利用地球化学方法作为油气勘探的一种辅助手段。在6个航次中采集了沉积物、底层海水及海面大气样品，测定了近50种化探指标，并采用稳健统计方法进行了数据处理和异常圈定。化探结果在油气藏上方发现了清晰的、具不同指标组合的综合化探异常，与邻近空构造形成鲜明的对照。圈闭顶部的块状异常和圈闭周绿的环状、半环状异常是下伏油气藏的良好指示，而剖面上呈锯齿状、平面上呈线状的异常则与断裂带有关。实践表明，建立已知油气藏上方的化探异常模式及解剖已知空构造上方的地球化学特征对于指导本区或邻区的化探异常评价是十分必要的。 相似文献
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An in situ resistivity profiler was developed to measure with minimal disruption, the near-surface porosity of shallow-water marine sands. Results from a siliciclastic site off NW Florida and two Bahamian carbonate sites (an ooid shoal and coral reef sand flat) suggest the following general features. First, there is a 5- to 15-mm thick zone of elevated porosity adjacent to the sediment-water interface. Porosity in this layer was from 0.05 to 0.25 (decimal porosity) greater than the subjacent values, and would be difficult to resolve using traditional measurement techniques. Second, average porosity at >10-mm depth was 0.38 /spl plusmn/ 0.01 at the siliciclastic site, 0.39 /spl plusmn/ 0.01 at the ooid shoal site, and 0.49 /spl plusmn/ 0.02 at the coral reef sand flat site; consistent with literature values. Third, individual profiles exhibited 0.05-0.15 fluctuations about the mean, with vertical length scales of 5-15 mm. These fluctuations may be the result of grain packing heterogeneities caused by hydrodynamic sorting during deposition and subsequent physical and biological mixing or could be artifacts caused by disruption of the grain framework. Fourth, ripple troughs at the siliciclastic sand site had a significantly higher near-surface porosity compared to ripple crests, due most likely to the presence of detrital material in the troughs. 相似文献