基于数字图像分割法的跨孔雷达走时层析成像

跨孔雷达走时层析成像主要利用雷达波的走时进行反演,走时提取的正确与否将直接影响到层析成像的效果。数字图像分割法基于凸集投影（POCS）方法,使用能量比彩色图像分割技术准确提取走时。数字图像分割法提取走时首先应用在折射地震波的数据处理中。笔者首次将数字图像分割法提取走时的方法应用到跨孔雷达走时层析成像中,使用迭代线性反演算法重建了雷达波速度场。反演过程中,使用最小二乘QR分解法（LSQR）求解线性方程组,利用弯曲射线追踪技术构建雅可比矩阵,走时的计算值则由多模板快速推进算法（MSFM）得到。为了验证数字图像分割法在走时层析成像中的效果,使用一组合成数据及一组实测数据分别对比了基于数字图像分割法和基于传统能量比法获得的层析成像反演结果。对比结果表明,使用数字图像分割法得到的层析成像结果更为精确,误差更小,能为判断地下雷达波速度场提供更为有力的帮助。     

利用定尺度小波变换比方法测量远震极远震P和PKIKP震相到时

许多起始缓慢的震相的到时不易测量准确, 人眼测量的到时往往偏后. 本文对定尺度Morlet小波变换比方法加以改善和简化之后, 测量了50条远震和极远震记录的初至震相P和PKIKP的到时. 在对结果的合理性和误差进行分析讨论的基础上, 肯定了该方法的有效性.       

Interpretation of magnetic anomalies of dikes using correlation factors

The magnetic anomaly due to a buried dike consists of the sum of two easily separated elementary functions. These functions, which have simple symmetry, are called even and odd functions. The correlation factors (r _0,1 for the even andr _0,2 for the odd function) between least-squares residual anomalies from even and odd functions are computed. Correlation values are used to determine the depth to the top and the half-width of the dike. The method also includes the determination of the index parameter and the amplitude coefficient. The validity of the method is tested against a theoretical and a field example where the parameters of the latter were determined by other investigators in comparing the results.     

利用局部高空间分辨率大气数据计算GRACE大气去混频模型

在计算GRACE重力场反演中的大气去混频模型时,针对ECMWFop或ERA-Interim大气数据空间水平分辨率不足的问题,提出了一种局部区域高空间水平分辨率大气数据与全球大气数据合理拼接融合的方法。利用欧洲局部区域的大气数据与ERA-Interim大气数据融合计算了一组改进的大气去混频模型,从谱域、空域及星间距离变率残差角度分析了改进大气去混频模型的质量。结果表明改进大气去混频模型相对于常规大气去混频模型的质量提高最大比例为1.87%,与AOD1BRL05相对于RL04的提高比例2.27%相当,验证了高空间水平分辨率大气数据确实有助于提高大气去混频模型质量的结论,为改进GRACE提取局部区域特定质量变化信号提供了一种方法。     

Application of the discordant outlier detection and separation system in the geosciences

Basically, two main types of statistical methods – robust and outlier-based – are available for handling experimental data; we document here the application of the outlier-based method. Due to the unavailability of a suitable software system for statistically correct application of the outlier-based method, a new computer program, DODESSYS (Discordant Outlier DEtection and Separation SYStem), was written for the application of 33 discordancy test variants to experimental data, constituting contaminated or uncontaminated normal statistical samples. We illustrate the application of the discordant outlier-based scheme by five specific examples; three include univariate data for which this procedure was specifically designed and two are for bivariate data for which this methodology can be easily adopted. We thus report new statistical information on two reference materials (granite G-2 and sediment IAEA-417), bryozoan species from eastern Oman, a new improved Na/K geothermometric equation, and a more significant correlation with water depth of the abundance of meiofauna from the Gulf of Mexico. Recently, two sets of multi-dimensional discrimination diagrams for basic as well as acid rocks have been proposed from statistically correct methodology of natural logarithm-transformation of element ratios; the diagrams also require that these ratios should be normally distributed. We present numerous examples of application of these new diagrams for inferring tectonic setting of Archaean to Recent rocks, both before and after testing the datasets for discordant outliers. We recommend that outlying observations should always be evaluated for their discordancy.     

基于图形界面的波形相关法拾取远震相对走时残差

利用图形界面操作集成两种波形相关法(多道互相关和自适应叠加)拾取远震走时残差,在该软件包中地震学研究者通过轻松点击鼠标等基本操作即可实现数据的预处理、地震波形的质量控制、走时残差结果的显示及对比分析等操作,提高远震震相走时残差的拾取效率和准确度.     

地震定位方法适用性分析

选取辽宁区域三种不同类型的六次地震事件,运用单纯型、Hyposat、HYP2000三种定位方法对其进行重新定位,产出的结果进行对比分析。结果表明,Hyposat方法在定位这三种类型的地震时,残差范围最小最为稳定,定位网内地震时震中差也相对比较小,较适用于内陆地震和矿震的地震定位。     

北京地震台地震走时表的研制

长期地震观测发现,北京地震台实际地震记录的震相走时与全球地震走时表IASP91之间存在走时偏差。结合北京地震台及周边地下40km精细速度结构的研究成果和AK135模型,构建其地震走时表的计算模型。通过对该地震台2003--2008年NCDSN地震观测实际走时比对,对模型结构进行修正,最终建立北京地震台地震走时表。     

近50 a博斯腾湖逐年水量收支估算与水平衡分析

据博斯腾湖流域1958-2010年期间主要河流开都河、黄水沟、清水河、孔雀河的逐年流量资料,结合焉耆盆地降水、蒸发要素的同期观测资料,对大湖区的逐年水量收支进行计算,并依据水量平衡原理对博湖大湖区残差水量进行了逐年分析。结果表明：（1）1958-2010年期间年均入湖水量14.34×10⁸ m³/a,其中入湖河水约占95%;年均输出水量13.96×10⁸ m³/a,其中大湖区输入孔雀河水量约占43%,湖面蒸发耗水量占57%;湖区年均蓄水量71.57±3.92×10⁸ m³10⁸ m³/a,湖水年均水位为1 047.01±0.94 m;（2）极端水文年度水量平衡分析指出：1986年为最枯年份,入湖河水是多年平均值的62%,而出湖河水量是多年平均值的153%,导致年内湖区水位下降0.94 m;2002年最丰年份入湖河水是多年平均值的2.6倍,致使年内水位上升0.80 m;（3）残差水量逐年“正负”变化指出,湖水与地下水之间存在互补关系,过去53 a间湖水补给地下水的年均水量为0.87×10⁸ m³/a。