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1.
ABSTRACT

The reliable and robust monitoring of air temperature distribution is essential for urban thermal environmental analysis. In this study, a stacking ensemble model consisting of multi-linear regression (MLR), support vector regression (SVR), and random forest (RF) optimized by the SVR is proposed to interpolate the daily maximum air temperature (Tmax) during summertime in a mega urban area. A total of 10 geographic variables, including the clear-sky averaged land surface temperature and the normalized difference vegetation index, were used as input variables. The stacking model was compared to Cokriging, three individual data-driven methods, and a simple average ensemble model, all through leave-one-station-out cross validation. The stacking model showed the best performance by improving the generalizability of the individual models and mitigating the sensitivity to the extreme daily Tmax. This study demonstrates that the stacking ensemble method can improve the accuracy of spatial interpolation of environmental variables in various research fields.  相似文献   
2.
广角地震的远偏移距折射初至含有地下深层的信息,提高远偏移距折射波信噪比能够有效提高初至拾取精度,对于深部结构的层析速度建模十分有利.超虚折射干涉法基于干涉原理对远道折射波进行增强,它在炮点和检波点都非常密集的情况下效果较好.然而,在应用于台站间距较大且环境噪声较强的广角海底地震仪(OBS)观测时,该方法对折射波的增强能力不足,而且容易产生虚假波形,造成增强后的折射波信噪比仍然较低.针对这种情况,本文提出基于相邻虚拟道叠加的超虚折射干涉法,通过叠加相邻虚拟道来提高远道与近道互相关的准确度,以达到稳定增强远道折射波信噪比的目的.理论实验和实际资料测试均显示,基于相邻虚拟道叠加的超虚折射干涉法在台站间距较大和信噪比较低的情况下能够准确构建虚拟道,且增强后的波形同相轴连续程度和信噪比均较高,有利于拾取高精度的折射初至到时.本文方法也可用于增强陆上炮间距较大的广角地震数据折射波.  相似文献   
3.
共反射元弧叠加方法在火山岩成像中的应用   总被引:14,自引:5,他引:9       下载免费PDF全文
常规叠加方法假设叠加的地震道集的反射波来自地下同一个反射点,而地表观测到 的反射波场在空间上小于菲涅尔体范围是不可分辨的. 本文根据火山岩体特征,用元弧描述 火山岩的反射界面. 将来自菲涅尔体范围内的反射波沿着元弧界面求和,进而扩大叠加次数 ,达到增加反射信号能量提高地震反射波的叠加成像质量的目的. 文中给出了反射波走时参 数与地下元弧反射界面之间的联系和叠加实现的步骤. 计算结果表明,元弧叠加方法能够提 高剖面的信噪比,增加反射波同相轴的连续性.  相似文献   
4.
水库大容量气枪震源激发条件优化实验研究   总被引:3,自引:2,他引:1  
通过人工拾取震相,统计记录台站数、台站最远观测距离、接收能量等3个参数,自主研发了最优工况处理软件来研判工况激发效果,并确定棉花滩水库最优工况为水深25m,枪阵沉放深度9m,枪阵尺寸7m×7m。对定点300次激发的每10次累计叠加结果进行分析后发现,叠加1090次时激发效果快速增强,100150次时缓慢增强,160240次时快速增强,250300次时缓慢增强,即随着叠加次数的增加,激发效果增强,传播距离和记录台数也逐步增加。  相似文献   
5.
从阵列信号处理的角度对地震勘探中一些重要的信号处理方法进行了较为全面的总结,包括地震勘探中的阵列设计、常用的抗干扰技术,组合法、叠加法、速度滤波和反滤波等。为了形成关于地震勘探中信号处理的一个较为完整的理论框架,给出了地震勘探的模型和地震勘探中信号处理所面对的信号环境,讨论了地震勘探中信号处理的目的所在。  相似文献   
6.
将用于图像处理的光顺技术引用到速度谱能量团曲面的处理环节,借以提高速度谱的分辨率,为最终获得高精确解提供一全新的途径.具体思路是基于路径积分优化法--Viterbi算法所具有的自动搜寻及获取最优解的功能,将其应用于地震资料处理中的速度自动拾取,使其向前做最大"能量团"的积分向后递归计算最优解--叠加速度,但这种解的准确性往往与所定义的目标函数--速度谱的分辨率有关.演算结果表明,Viterbi算法与关顺处理技术的有机结合,不仅提高了速度提取的精度,而且实现了速度的自动拾取,可提高常规地震资料处理的效率,从而可快捷地为叠前深度偏移提供所需初始速度模型.  相似文献   
7.
水库大容量气枪震源激发条件优化实验研究   总被引:1,自引:0,他引:1  
Through manual pickup of seismic phases,the number of recording stations,the farthest observation distance of station and received energy are determined,then optimal operating condition processing software is developed to evaluate the excitation effect of operating conditions. The optimal operating conditions in the Mianhuatan Reservoir are determined using this software. They are: optimal water depth 25 m,airgun array sink depth 9m and airgun array size 7m × 7m. At the same time,accumulative stacking results for every 10 times are analyzed for 300 fixed-point excitations. It is concluded that the excitation effect shows a rapidly rising trend at 10 to 90 times stacking,a slowly rising trend at 100 to 150 times stacking,a rapidly rising trend at 160 to 240 times stacking,and a slowly rising trend at 250 to 300 times stacking. As the number of stacking increases,the propagation distance and the number of recording stations also increase gradually.  相似文献   
8.
可控震源的激发过程精确可控、可重复性高。本文评估了重复激发形成的多道记录的信号增强方法,包括叠加方法和有效信号直接分离方法。相比线性叠加,加权叠加充分利用了有效信号的一致性,能进一步压制噪声,提高叠加记录的信噪比。相比时间域相位加权叠加,Semblance加权叠加更加稳定。时频域相位加权叠加能在时频域压制随机分散分布的噪声信号,叠加信号更加清晰。本文中,采用标准SVD分离获得的信号同线性叠加结果类似。本文利用密集分布的临时台阵评价地学长江计划安徽实验中低频可控震源在庐江第2激发点的激发效果。对比不同的处理流程发现,先互相关检测信号再进行时频域相位加权叠加能够取得最佳的处理效果,通过200多次重复激发,可以在50km范围内提取到较清晰的有效信号。  相似文献   
9.
利用测高卫星的冻结轨道特征计算了正常点轨迹,利用三次B样条函数和Stacking技术内插计算了T/P、ERS-1/2和Geosat测高数据在正常点的平均海面高,改善了测高数据的精度和分辨率.最后,利用正常点上的平均海面高反演了多种分辨率的海域重力异常,其中所反演的海域重力异常的标准差为mGal级.  相似文献   
10.
Holocene deposits exhibit distinct, predictable and chronologically constrained facies patterns that are quite useful as appropriate modern analogs for interpreting the ancient record. In this study, we examined the sedimentary response of the Po Plain coastal system to short-term (millennial-scale) relative fluctuations of sea level through high-resolution sequence-stratigraphic analysis of the Holocene succession.Meters-thick parasequences form the building blocks of stratigraphic architecture. Above the Younger Dryas paleosol, a prominent stratigraphic marker that demarcates the transgressive surface, Early Holocene parasequences (#s 1–3) record alternating periods of rapid flooding and gradual shoaling, and are stacked in a retrogradational pattern that mostly reflects stepped, post-glacial eustatic rise. Conversely, Middle to Late Holocene parasequences (#s 4–8) record a complex, pattern of coastal progradation and delta upbuilding that took place following sea-level stabilization at highstand, starting at about 7 cal ky BP. The prominent transgressive surface at the base of parasequence 1 correlates with the period of rapid, global sea-level rise at the onset of the Holocene (MWP-1B), whereas flooding surfaces associated with parasequences 2 and 3 apparently reflect minor Early Holocene eustatic jumps reported in the literature. Changes in shoreline trajectory, parasequence architecture and lithofacies distribution during the following eustatic highstand had, instead, an overwhelming autogenic component, mostly driven by river avulsions, delta lobe switching, local subsidence and sediment compaction. We document a ∼1000-year delayed response of the coastal depositional system to marine incursion, farther inland from the maximum landward position of the shoreline. A dramatic reduction in sediment flux due to fluvial avulsion resulted in marine inundation in back-barrier position, whereas coastal progradation was simultaneously taking place basinwards.We demonstrate that the landward equivalents of marine flooding surfaces (parasequence boundaries) may be defined by brackish and freshwater fossil assemblages, and traced for tens of kilometers into the non-marine realm. This makes millennial-scale parasequences, whether auto- or allogenic in origin, much more powerful than systems tracts for mapping detailed extents and volumes of sediment bodies.The Holocene parasequences of the Po coastal plain, with strong age control and a detailed understanding of sea-level variation, may provide insight into the driving mechanisms and predictability of successions characterized by similar depositional styles, but with poor age constraint, resulting in more robust interpretations of the ancient record.  相似文献   
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