不同标度震级关系和台基影响问题探讨

利用近年中国数字地震台网观测报告中的中国及邻区地震目录资料,取能够同时计算面波震级MS和近震震级ML的地震,拟合出2种震级之间的关系,发现与过去使用30余年的换算公式存在系统差别。考虑现代化地震数字观测系统有动态范围大、频带宽、台站多、覆盖区域广、测定精度高的特点,由此拟合的关系应当更可靠。考虑不同误差因素统计面波震级MS和近震震级ML的关系表明,2种震级之间换算和不换算的差别并不大,因此建议MS和ML震级之间不换算为宜。分析地震台站的场地响应发现:一些基岩台的放大因子在1附近,场地响应不随频率变化;处于沉积土层的台站,放大因子在低频段大于1,高频段小于1;还有一些台站在某个频段范围大于1,或者小于1。另外,沉积土层台站的单台震级和台网平均震级差也随周期增大,呈现由负到正的增长趋势。看来并不存在固定的台站校正系数,因此不能把台站校正作为提高震级测定精度的方法。     

GPS sidereal filtering: coordinate- and carrier-phase-level strategies

Multipath error is considered one of the major errors affecting GPS observations. One can benefit from the repetition of satellite geometry approximately every sidereal day, and apply filtering to help minimize this error. For GPS data at 1 s interval processed using a double-difference strategy, using the day-to-day coordinate or carrier-phase residual autocorrelation determined with a 10-h window leads to the steadiest estimates of the error-repeat lag, although a window as short as 2 h can produce an acceptable value with > 97% of the optimal lag’s correlation. We conclude that although the lag may vary with time, such variation is marginal and there is little advantage in using a satellite-specific or other time-varying lag in double-difference processing. We filter the GPS data either by stacking a number of days of processed coordinate residuals using the optimum “sidereal” lag (23 h 55 m 54 s), and removing these stacked residuals from the day in question (coordinate space), or by a similar method using double-difference carrier-phase residuals (observational space). Either method results in more consistent and homogeneous set of coordinates throughout the dataset compared with unfiltered processing. Coordinate stacking reduces geometry-related repeating errors (mainly multipath) better than carrier-phase residual stacking, although the latter takes less processing time to achieve final filtered coordinates. Thus, the optimal stacking method will depend on whether coordinate precision or computational time is the over-riding criterion.     

采样过程和模数转换对记录的影响及“真实地面运动”获取——地震学上用的数字信号处理的基本原理和实例(讲座3)

通过采样过程和模数转换对记录影响的分析,讨论了数字地震仪记录的动态范围,以及如何使用谱分析方法去除仪器对最终记录的影响,以便获取“真实地面运动”的近似。     

GPS技术在金川露天矿边坡变形监测中的应用

本文结合金川露天矿边坡变形GPS监测研究,主要论述监测基点的选择,基点WGS-84坐标的确定,变形监测网的布设,GPS数据采集、处理和质量,坐标转换的实施等,给出反演推出的若干四等三角点及其它控制点的变形数据,这些数据和造成变形的物理成因符合得很好,最后概括出GPS技术应用于变形观测的若干优点。     

Model Simulations on the Variability of Particulate MSA to Non-Sea-Salt Sulfate Ratio in the Marine Environment

A box model was constructed to investigate connections between the particulate MSA to non-sea-salt sulfate ratio, R, and DMS chemistry in a clean marine boundary layer. The simulations demonstrated that R varies widely with particle size, which must be taken into account when interpreting field measurements or comparing them with each other. In addition to DMS gas-phase chemistry, R in the submicron size range was shown to be sensitive to the factors dictating sulfate production via cloud processing, to the removal of SO₂ from the boundary layer by dry deposition and sea-salt oxidation, to the entrainment of SO₂ from the free troposphere, to the relative concentration of sub- and supermicron particles, and to meteorology. Three potential explanations for the increase of R toward high-latitudes during the summer were found: larger MSA yields from DMS oxidation at high latitudes, larger DMSO yields from DMS oxidation followed by the conversion of DMSO to MSA at high latitudes, or lower ambient H₂O₂ concentrations at high latitudes leading to less efficient sulfate production in clouds. Possible reasons for the large seasonal amplitude of R at mid and high latitudes include seasonal changes in the partitioning of DMS oxidation to the OH and NO₃ initiated pathways, seasonal changes in the concentration of species participating the DMS-OH reaction pathway, or the existence of a SO₂ source other than DMS oxidation in the marine boundary layer. Even small anthropogenic perturbations were shown to have a potential to alter the MSA to non-sea-salt sulfate ratio.     

9608号台风登陆北上总能量变化及渤海高压维持

首先分析了属于台风与西风槽的相互作用型的９６０８号台风在其登陆泊台风核心区总能量及其组成部分的变化。结果指出,决定总能量再度增长的主要是潜热能,而此时潜热能的增长是同台风东侧低层偏南急流有密度关系。台风的东北象限内潜热能增长最盛,特大暴雨区恰也在这个象限。其次利用对流层高层散度风场与旋转风场的配置,从散度风动勇与旋转风动能之间的转换关系,半定量地估计台风东侧黄海、渤海、日本海高压上空反气旋环流的增     

Ages of sediment-hosted Himalayan Pb–Zn–Cu–Ag polymetallic deposits in the Lanping basin,China: Re–Os geochronology of molybdenite and Sm–Nd dating of calcite

The Lanping basin is a significant Pb–Zn–Cu–Ag mineralization belt of the Sanjiang Tethyan metallogenic province in China. Over 100 thrust-controlled, sediment-hosted, Himalayan base metal deposits have been discovered in this basin, including the largest sandstone-hosted Pb–Zn deposit in the world (Jinding), and several Cu ± Ag ± Co deposits (Baiyangping, Baiyangchang and Jinman). These deposits, with total reserves of over 16.0 Mt Pb + Zn, 0.6 Mt Cu, and 7000 t Ag, are mainly hosted in Meso-Cenozoic mottled clastic rocks, and strictly controlled by two Cenozoic thrust systems developed in the western and eastern segments of the Lanping basin.To define the metallogenic history of the study area, we dated nine calcite samples associated with copper sulfides from the Jinman Cu deposit by the Sm–Nd method and five molybdenite samples from the Liancheng Cu–Mo deposit by the Re–Os method. The calcite Sm–Nd age for the Jinman deposit (58 ± 5 Ma) and the molybdenite Re–Os age for the Liancheng deposit (48 ± 2 Ma), together with previously published chronological data, demonstrate (1) the Cu–Ag mineralization in the western Lanping basin mainly occurred in three episodes (i.e., ∼56–54, 51–48, and 31–29 Ma), corresponding to the main- and late-collisional stages of the Indo–Asian orogeny; and (2) the Pb–Zn–Ag (±Cu) mineralization in the eastern Lanping basin lacked precise and direct dating, however, the apatite fission track ages of several representative deposits (21 ± 4 Ma to 32 ± 5 Ma) may offer some constraints on the mineralization age.     

An Experimental Study on A Trapezoidal Pendulum Wave Energy Converter in Regular Waves

Experimental studies were conducted on a trapezoidal pendulum wave energy converter in regular waves. To obtain the incident wave height, the analytical method (AM) was used to separate the incident and reflected waves propagating in a wave flume by analysing wave records measured at two locations. The response amplitude operator (RAO), primary conversion efficiency and the total conversion efficiency of the wave energy converter were studied; furthermore, the power take-off damping coefficients corresponding to the load resistances in the experiment were also obtained. The findings demonstrate that the natural period for a pendulum wave energy converter is relatively large. A lower load resistance gives rise to a larger damping coefficient. The model shows relatively higher wave energy conversion efficiency in the range of 1.0?1.2 s for the incident wave period. The maximum primary conversion efficiency achieved was 55.5%, and the maximum overall conversion efficiency was 39.4%.     

不同截止高度角下BDS-3SPP精度分析

针对卫星可见数与历元可用率较低情况下的BDS-3定位性能,本文基于MEGX跟踪站BDS-3与GPS实测数据,分析了不同高度角（10°、20°、30°、40°）下BDS-3卫星B1I、B1C、B2a、B3I,以及GPS系统L1频率的单点定位（SPP）精度。研究发现,BDS-3平均卫星可见数与卫星空间几何构型优于GPS,且随着高度角的增加呈线性变化。BDS-3的4个频率的SPP精度随着高度角的增加呈先增加后降低的趋势,高度角为20°时,定位精度最高,高度角达到40°时,定位精度最低,且历元可用率也最低;但B1I和B3I历元可用率仍大于90%,而B1C和B2a历元可用率大于70%;不论是SPP定位精度还是历元可用率,均优于GPS系统L1频率。     

黑龙江省耕地非农化的空间格局与重心曲线分析

为了揭示耕地非农化的空间格局与重心曲线,为耕地资源保护和利用政策制定提供决策支撑,该文以黑龙江省1980、1990、2000、2010、2015年土地利用数据为基础,运用GIS空间分析方法,引入重心模型分析黑龙江省耕地非农化的空间格局及重心曲线。研究结果表明:1980—2015年黑龙江省耕地非农化发展不平衡,4个时期耕地非农化面积呈波动增长的趋势;耕地非农化等级空间分布特征明显,等级较高的城市集中分布在西部地区;耕地非农化速度等级的重心曲线在空间分布上,具有从中心向边缘延伸的特点;耕地非农化围绕中心地区进行,其空间扩散路径在图形上呈现出一个回旋状。