GPS测站坐标非线性变化研究方法的比较与分析

以GPS测站残差时间序列为研究对象,采用自回归滑动平均模型（ARMA）的两种建模方法（Box-Jenkins方法和Pandit-Wu方法）和三角函数法对其进行建模拟合与分析比较。通过实验发现Pandit-Wu方法拟合效果最好,Box-Jenkins方法次之,三角函数法最差,但是通过不同的测站残差数据实验比较也发现三角函数法能更加直观地体现出非线性变化的规律,有利于进一步分析非线性变化规律的性质与机制,因此,同样具有深入研究的价值。     

微波消解-多接收电感耦合等离子体质谱高精度测定锶钕同位素组成

应用多接收器电感耦合等离子体质谱仪(MC-ICP-MS)测定地质样品中锶、钕同位素组成时,化学前处理流程冗长、复杂,且容易出现样品未完全溶解的现象。本文采用微波消解法消解样品,在保证消解效果的前提下有效地缩短了溶样时间,在此基础上研究了锶、钕化学分离和质谱测试流程,重点考察了树脂柱的回收率和记忆效应。结果表明:树脂经10次使用后的锶、钕流程空白均低于1.0 ng,但回收率明显下降,分别由原来的98%和90%降到20%和50%,若待测样品中锶、钕含量较低,所接收的锶、钕则达不到质谱仪测试范围,因此建议锶特效树脂使用次数不超过5次,AG50W-X8稀土柱和Ln树脂使用次数不超过10次。整套流程应用于国际地质标准样品(BCR-2、W-2a、BHVO-2、AGV-2)的锶、钕分离,MC-ICP-MS所得的87Sr/86Sr、143Nd/144Nd测定值与文献报道值一致,仪器的内精度2SE(n=50)和方法的外精度2SD(n=6)均优于0.0015%,表明该流程可以满足地质样品中锶、钕同位素高精度测定的要求。     

北斗电离层模型改正精度分析

电离层误差是影响单频用户机定位精度的主要误差源。卫星导航系统播发电离层模型改正参数供用户使用,模型改正精度会对定位结果产生直接影响。北斗卫星导航系统根据连续监测站实测数据,计算并发播地理坐标系下8参数Klobuchar电离层模型参数,且每2 h更新一次。为了科学评估北斗电离层模型改正效果,文中基于北斗最新观测数据,首先,以CODE提供的GIM模型作为比对基准,详细分析了不同纬度地区、不同时间段内的电离层模型改正精度;其次,分别按照以下定位模式进行计算:1)北斗单频不加电离层改正,2)北斗单频+北斗K8模型,3)北斗单频+GPS K8模型,并分析了电离层改正残差对定位结果影响大小。结果表明,北斗电离层模型改正精度在北半球优于南半球,中纬度地区改正效果最好,其改正残差RMS均值在0.6 m左右,往低纬和高纬度地区呈递减趋势;北京地区北斗单频+北斗K8模型定位精度优于GPS K8模型。     

http://www.sciencedirect.com/science/article/pii/S1674987112001247

The Sinai Peninsula has been recognized as a subplate of the African Plate located at the triple junction of the Gulf of Suez rift, the Dead Sea Transform fault, and the Red Sea rift. The upper and lower crustal structures of this tectonically active, rapidly developing region are yet poorly understood because of many limitations. For this reason, a set of P- and S-wave travel times recorded at 14 seismic stations belonging to the Egyptian National Seismographic Network (ENSN) from 111 local and regional events are analyzed to investigate the crustal structures and the locations of the seismogenic zones beneath central and southern Sinai. Because the velocity model used for routine earthquake location by ENSN is one-dimensional, the travel-time residuals will show lateral heterogeneity of the velocity structures and unmodeled vertical structures. Seismic activity is strong along the eastern and southern borders of the study area but low to moderate along the northern boundary and the Gulf of Suez to the west. The crustal V_p/V_s ratio is 1.74 from shallow (depth ≤ 10 km) earthquakes and 1.76 from deeper (depth > 10 km) crustal events. The majority of the regional and local travel-time residuals are positive relative to the Preliminary Reference Earth Model (PREM), implying that the seismic stations are located above widely distributed, tectonically-induced low-velocity zones. These low-velocity zones are mostly related to the local crustal faults affecting the sedimentary section and the basement complex as well as the rifting processes prevailing in the northern Red Sea region and the ascending of hot mantle materials along crustal fractures. The delineation of these low-velocity zones and the locations of big crustal earthquakes enable the identification of areas prone to intense seismotectonic activities, which should be excluded from major future development projects and large constructions in central and southern Sinai.     

Stability of P Saturated Water Treatment Residuals under Different Levels of Dissolved Oxygen

Water treatment residuals (WTRs) are effective phosphorus (P) immobilizers that have been used in constructed wetlands (CWs). In CWs, dissolved oxygen (DO) levels vary from location to location and fluctuate over time. Therefore, this work accessed the stability of P saturated ferric and alum water treatment residuals (FARs) under low (<1 mg/L), medium (2–4 mg/L), and high (5–8 mg/L) DO levels. In the experiments, which had a 40‐day duration, three stages of P release from the P saturated FARs were observed: an initial rapid P desorption stage, followed by a P re‐adsorption stage, and a P desorption balance stage. The strongest bonding between P and FARs occurred at the low DO level. A limited amount of Fe and Al was released from the P saturated FARs. Interestingly, the P in the FARs tended to transform from the Al bound P to the Fe bound P, and this transformation was stronger at lower DO levels. However, no more than 1.12% of the total P in the P saturated FARs was desorbed under any of these DO levels. Therefore, FARs can be considered as a safe P adsorption medium for CWs.     

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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.