浅谈如何进行电线积冰的观测记录和处理

电线积冰是国务院气象主管机构指定的观测项目之一,山西省目前有18个国家基本（准）站需进行电线积冰项目的观测。因地形地貌和气候特点等原因,电线积冰现象在一些台站出现频次较少,观测人员容易忽视对电线积冰观测知识和技术的学习,在遇到该现象时不能准确客观地进行记载。为此笔者总结了电线积冰记录处理中一些比较特殊的地方,希望对观测人员业务工作有所帮助。     

2020年新疆于田MS6.4地震前地磁谐波振幅比变化特征分析

以2020年6月26日于田M_S6.4地震为例, 采用地磁谐波振幅比法, 选用距震中370 km和360 km范围内的且末台、 狮泉河台所记录到的秒值连续波形数据, 对震前地磁异常进行了提取和回溯性分析, 发现地磁谐波振幅比反映了观测点深部电阻率变化, 2020年于田M_S6.4地震前且末台和狮泉河台地磁谐波振幅比出现了较明显的异常现象。 异常特征有: ① 地磁谐波振幅比Y_ZHx和Y_ZHy主要表现为“下降—转折—恢复”的形态, 地震发生在下降型变化恢复之后上升阶段; ② 震前约2年起, 且末台和狮泉河台谐波振幅比表现长短周期变化不同步或NS向与EW向变化不同步的现象; ③ 且末台Y_ZHx(NS)和狮泉河台Y_ZHy(EW)谐波振幅比异常变化中的转折上升形态具有自较长周期向较短周期的迁移现象; ④ 狮泉河台谐波振幅比趋势性异常起始时间早于且末台, 持续时间平均2年左右, 最大异常幅度达到0.04; ⑤ 且末台Y_ZHx(NS)和狮泉河台Y_ZHy(EW)异常相比对应其他分量更为显著, 这也许震中和台站所在位置有关系; ⑥ 地震前和田大地电场(距震中约265 km)岩体裂隙优势方位角(α)也显示异常变化, 可见该地震前多地球物理探测参量的异常响应, 呈现多地球物理量耦合, 增加了异常可信度。     

2017年11月23日重庆武隆5.0级地震前地磁谐波振幅比异常研究

近年来,地磁谐波振幅比方法在国内得到较广泛的应用,并成为一种较为有效的地震预测方法。本文利用谐波振幅比方法,对2017年11月23日重庆武隆5.0级地震震中附近台站的地磁三分量数据进行计算,并分析了各台站10~60min周期谐波振幅比值异常特征。研究发现,异常台站几乎均位于震源机制解的拉张区(P波向下的区域),具有象限分布特征;异常台站NS向谐波振幅比值变化存在分层现象,短周期(浅部)的变化与长周期(深部)变化成相反相位,从电磁学机理看,浅部与深部之间存在EW向的面电流;近震中台站的异常低点时间存在由长周期(深部)向短周期(浅部)迁移的现象。     

Preliminary Study of the Ability of Large-scale Deformation Observed by Lunar Based InSAR—Taking Vertical Displacement of Solid Earth Tide as an Example

Based on the principle of InSAR (Interferometirc Synthetic Aperture Radar) characterized by large-scale, continuity, permanency and dynamic, we took vertical displacement of solid Earth tide as an example to simulate the large-scale deformation observed by lunar based InSAR for the first time in the study and the observation ability was analyzed. Solid Earth tide has a feature of a large-space distribution range and the lunar based InSAR exhibits a feature of an ultra-wide swath imaging. According to these features, a simplified observation geometry model was established and a mid-low latitudes area with 50 degrees span in both longitude and latitude was selected as the simulation area. Then the revisit time intervals of the lunar based SAR for the selected area and the tidal vertical displacements at the points scanned by the radar were calculated. The time differentials were further computed to get the relative vertical deformation of the solid Earth tide. The simulation results show that the revisit period of the lunar based radar is about 24.8 hours and the maximum vertical displacement in 30 days is up to 30 cm. Since the designed accuracy of the lunar based InSAR reaches several centimeters, the observing of the vertical displacement of the solid Earth tide by using the lunar based InSAR is feasible in theory as the maximum magnitude of the vertical displacement is 1 order of magnitude larger than the designed accuracy. Theoretically ,solid Earth tide is observable by using lunar based InSAR in a sizable area.We can also use the observation data to study the temporal and spatial variation characteristics when observation time lasts two revisit periods or more. On the other hand,the result of the study also provides references for the parameter designing of other observations using the lunar based InSAR, especially for observing large-scale geodynamic phenomena.     

南海海洋地磁固定观测站建设初步研究

为填补我国海洋地磁固定观测的空白,支撑科学研究、防灾减灾、海洋资源开发,维护国家的海洋权益和履行我国在南海海域负有的国际责任,急需在南海建设岛礁和海底地磁固定观测站。通过初步分析国外海洋地磁观测站案例、南海岛礁基础设施现状以及海底观测网计划实施情况,认为南海海洋地磁固定观测站建设的条件已经成熟。文中给出了合理空间布局、分步实施、因地制宜及智能化观测的建议。     

DZN3型自动土壤水分观测仪故障处理及日常维护

作为全国重要水稻生产基地的湖南,因夏秋多旱的气候特征,水稻种植经常受干旱影响而减产。为做好气象为农服务工作,湖南省气象局从2010年开始,在全省建设了60个自动土壤水分观测站,显著改进了土壤水分观测手段和方法,提升了现代农业气象业务和干旱监测服务水平。本文简要介绍了DZN3型自动土壤水分观测仪的工作原理和系统结构,在总结省、市、县三级维护保障实践基础上,重点阐述了DZN3型自动土壤水分观测仪常见故障的分析及排查,对台站日常巡查维护及有关注意事项提出了建议。为气象部门基层台站业务人员提高维护维修时效,降低故障发生概率,提供借鉴与参考。     

地球磁场偶极子和非偶极子分量变化特征及其相关的地球深部过程

通过分析１９００年以来每５ａ地球磁场各阶球谐系数的相关系数发现,地球磁场偶极子分量的ρ值在１９０５-１９７０年基本保持不变,１９７０-１９８５年下降,１９８５-１９９５年又上升,呈Ｖ字型变化。而非偶极子分量的　值则具有周期性变化,在１９１５年、１９４５年和１９８０年出现峰值,在１９３５年和１９６５年则处于低谷,变化周期约为３０ａ。通过分析地球磁场非偶极子分量　值周期变化与日长周期变化的相关性,得出两点新的认识：１．非偶极子分量的周期性变化与核幔边界耦合过程相关,而偶极子分量的变化对应外核的深部过程;２．外核顶部流体具有周期性的变化,其变化周期与日长及非偶极子分量的变化周期一致。     

Nonlinear and multifractal approaches of the geomagnetic field

Recent nonlinear dynamics techniques have been developed to analyse chaotic time series data. We first summarize the procedure which gives an appropriate reconstruction of the unknown dynamics from scalar measurements in a pseudophase space. It permits, firstly, the representation of the trajectories of the dynamical system—they define an attractor when the system is dissipative—by preserving its topological properties. We then present the invariant measures and ergodic quantities such as the multifractal spectrum and Lyapunov exponents which can be estimated on the reconstructed attractor. The multifractal analysis provides us with a characterization of the scaling energy of the process whereas the Lyapunov exponent gives another statistical measure of the stability of the dynamics. The estimation of these quantities was tested on synthetic data. The nonlinear and multifractal analyses were finally applied to the hourly mean values of the magnetic field recorded at the Eskdalemuir (ESK) observatory over 79 years (692,520 data measurements for each component). The estimations of a 5-dimensional pseudo-phase space and a positive Lyapunov exponent confirm the possibility of low-dimensional deterministic chaos in the magnetic field observations at ESK observatory. The correlation between the solar activity (the Wolf number), the unstable nature of the magnetic field, and the singularity spectrum points out the forcing of the solar cycles on the dynamics of the magnetic field at ESK observatory.     

The Most Geomagnetically Disturbed 24 Hours

Geomagnetically disturbed periods, characterized by the maximum average 24-hour global disturbances are considered. Gumbel's first asymptotic distribution of extreme values is used to predict the occurrence of major magnetic storm periods. A geomagnetic storm similar to the one recorded on March 13 - 14, 1998, would be expected to occur within the next 13 solar cycles. The present analysis corroborates the substantial increase of the level of magnetic disturbances from solar cycle to solar cycle.     

1998年初北京地区震磁监测

为了加强北京地区地震活动性的监视预报,１９９８年１－２月开展了北京测网与临时台相互配合的地磁加强观测。根据压磁理论与地震应磁效应,应用同步差值,图像演化,快谱幅比等多种方法,分析处理了大量地磁资料,研究了地磁时空变化,探讨了可能存在的震磁前兆消息。