Applications of Savitzky-Golay Filter for Seismic Random Noise Reduction

This article utilizes Savitzky–Golay (SG) filter to eliminate seismic random noise. This is a novel method for seismic random noise reduction in which SG filter adopts piecewise weighted polynomial via leastsquares estimation. Therefore, effective smoothing is achieved in extracting the original signal from noise environment while retaining the shape of the signal as close as possible to the original one. Although there are lots of classical methods such as Wiener filtering and wavelet denoising applied to eliminate seismic random noise, the SG filter outperforms them in approximating the true signal. SG filter will obtain a good tradeoff in waveform smoothing and valid signal preservation under suitable conditions. These are the appropriate window size and the polynomial degree. Through examples from synthetic seismic signals and field seismic data, we demonstrate the good performance of SG filter by comparing it with the Wiener filtering and wavelet denoising methods.     

川滇GPS地壳形变监测网的观测与数据处理

介绍中美合作建立的川滇ＧＰＳ地壳形变监测网的布设和观测情况。利用ＧＡＭＩＴ和ＧＬＯＢＫ软件分别对已完成的两期观测数据进行了处理，基线相对精度优于０．１ｐｐｍ。对两期观测的部分基线结果作了比较，得出了一些有益的结论     

青海省祁连县大疙瘩5.0级地震宏观考察

1983年7月27日青海省祁连县境内发生了一次有感地震,为了验证我们前两年工作中所做的结论,组织了现场考察,并对原仪器震中进行了修订。现将此次考察结果叙述如下: 1.地震参数发震时间:1983年7月27日8时21分     

Magnetic order in crocidolite asbestos

Magnetic properties of two samples of crocidolite (blue asbestos) have been examined using susceptibility and magnetization measurements, neutron diffraction, and Mössbauer spectroscopy. Both samples order magnetically at 30±1 K with a structure in which iron ions in the ribbons parallel to c are all coupled ferromagnetically but the moments of adjacent ribbons are oppositely aligned. The iron moments are oriented at angles of about 69°, 36°, 69° with the a, b, c axes, respectively. A spin flop transition of the antiferromagnetically coupled ribbons occurs in an applied field of 15 kOe at 4.2 K, and a ratio of intraribbon to interribbon exchange interactions of about 10 is inferred. Mössbauer spectra at 4.2 K are decomposed into a ferric pattern with a hyperfine field of 550 kOe, associated with M2 sites, and two ferrous patterns with hyperfine fields of 200 and 100 kOe, associated with M1 and M3 sites, respectively. Each ferrous hyperfine field is oriented perpendicular to V _zz , the principal component of the electric field gradient, which is negative for both sites: V _zz =?2.65 mm/s, η=0.1 for M1 and V _zz =?2.9 mm/s, η=0.3 for M3. As in sheet silicates, the field gradients suggest pseudo-trigonal distortions of the ferrous sites symmetry, which stabilize ⁵ A _1g orbital singlet states.     

Magnetic order in grunerite,Fe7Si8O22(OH)2A quasi-one dimensional antiferromagnet with a spin canting transition

Magnetization and neutron diffraction measurements have been made on grunerite, Fe₇Si₈O₂₂(OH)₂, a monoclinic double-chain silicate with Fe²⁺ octahedral bands. The mineral orders antiferromagnetically at 47K into a collinear structure with a second transition at 8K to a canted arrangement. The magnetic susceptibility follows a Curie-Weiss Law above 120K, with a paramagnetic Curie temeprature ?_p=67K. Magnetization measurements below 47K indicate a spin-flop or metamagnetic transition in an applied field of about 12KOe. Powder neutron diffraction measurements between 8–45K reveal that all the Fe²⁺ spins within an octahedral band are ferromagnetically coupled parallel to the b axis, with each band antiferromagnetically coupled to neighboring bands. Below 8K Fe²⁺ spins at the M1 and M4 sites are canted away from the b axis, whereas those at the M2 and M3 sites are not significantly affected. The ordered Fe²⁺ moment on the M4 site is substantially lower than those on the other sites, most likely indicating strong covalency effects, i.e. considerable spin transfer to neighboring oxygen atoms.     

副高强度短时期演变的诊断分析

一、前言 西太平洋副热带高压(以下简称副高)是影响我国夏季天气的主要天气系统之一。六十年代以来,我国气象工作者探索了它的活动规律,取得了许多研究成果。本文是对于具有一定特点的两次副高个例作的诊断分析。这两次不同日期的副高,它们在500毫巴图上看起来很相类似,似乎都强盛,但是它们的短时期演变却显然不同。其中1971年5     

集合数值预报在洪水预报中的应用进展

水文集合预报是近几年正在形成和发展的水文预报分支,其发展大致可分为两个阶段:第1阶段是1970年至20世纪末进行的长期径流预报,第2阶段从21世纪开始,主要学习气象数值预报中集合预报的概念在短期水文集合预报中的应用。目前,除了单一预报中心的集合预报系统在水文集合预报中应用外,多个预报中心的集合预报大集合也逐渐被应用于流域水文预报,甚至一些小流域的洪水预报。如利用TIGGE(THORPEX Interactive Grand Global Ensemble)集合预报驱动形成的大气-水文-水力的串联系统进行早期的洪水预警研究,将全球集合预报作为洪水模型输入的有限区域模式的初始条件和侧边界条件的研究。这些均表明,基于水文集合预报的洪水预报增加了预报附加值,并能够延长预警提前时间。以欧洲中期天气预报中心的欧洲洪水预警系统(EFAS)和美国NOAA的先进水文预报系统(AHPS)为代表,实现了集合预报在洪水中的实时业务预报,但仍存在数据处理和计算量大,以及如何基于集合水文预报做决策等问题。对于水文集合预报的前处理和后处理的各种技术已处于探索和验证阶段,如何更好地理解基于概率预报的洪水预警决策仍存在许多困难和挑战。     

西北区域气象计量检定实验室量值比对分析

为验证西北区域各省（区）气象计量检定机构的检定能力,2014年宁夏气象计量检定所作为主导实验室组织开展温度、湿度、气压3个要素量值比对工作。比对采用圆环形路线,比对样品选用自动气象站传感器。参比实验室按照规定的比对方案对比对样品进行比对实验及不确定度评定,主导实验室对比对数据进行汇总分析,采用归一化偏差方法分析评价比对结果。比对结果：温度与气压实验室比对结果满意,湿度实验室比对结果较满意。参比样品的比对数据真实,结果可信,较为客观地反映了西北区域各参比实验室的检定/校准水平及气象计量标准装置的现状,有效识别了参加量值比对实验室存在的问题,对促进实验室检定能力的提高具有重要意义。     

Climate-growth relationships of subalpine fir (Abies fargesii) across the altitudinal range in the Shennongjia Mountains, central China

Dendroecological techniques were employed to explore the growth response of subalpine fir (Abies fargesii) to climatic conditions across its altitudinal range in both the north and south aspects in the Shennongjia Mountains, central China. Correlation function analyses indicated that temperatures in current summer were significantly negatively correlated with fir radial growth at the lower limits, while temperatures in previous autumn and in current spring showed significantly positive correlations with fir radial growth at the mid- and high-elevations in both aspects. Radial growth of the subalpine fir was significantly and positively influenced by precipitation in previous autumn and in current spring at the lower elevations and by precipitation in current spring at the mid-elevations, while precipitation had no significant effects on its radial growth at the upper elevations. Moving correlation functions showed that temperatures in early spring of the current year (i.e., February-April) had a relatively stable effect on tree growth over time at the mid- and upper-elevations in both aspects. Thus, the growth of the subalpine fir responded differently to climatic conditions along the altitudinal gradient, showing that the importance of temperatures for the fir radial growth increased while the importance of precipitation decreased with increasing altitude in both aspects in the Shennongjia Mountains, central China.