边界层辐合线发展成飑线的数值试验

利用高分辨率η坐标模式，以一个实际飑线个例的常规资料为初值，通过嵌入一定强度的边界中层尺度辐合线，进行了边界层辐合线型飑线激发的数值试验，结果表明，飑线实例的大尺度环境场提供了累积的有效浮力能，小尺度积云对流则通过对流翻腾提供高层水汽凝结潜热加热和低层降温冷却，而中尺度幅合线通过提供带状辐合上升运动，起着胚胎和组织积云对流的作用，这样大、中、小三种尺度相互作用导致了边界层中尺度辐合线发展成为飑线。     

利用风廓线雷达资料分析大理机场飑线天气过程的风垂直变化特征

飑线天气现象是航空气象中危险和复杂的天气现象之一,2018年大理机场出现两次飑线天气过程,利用风廓线雷达资料和航空气象地面观测资料,分析两次飑线天气过程的风垂直变化特征。结果表明:(1)在飑线天气过程开始前2～4 h,从底层到高层均出现明显的上升运动,飑现象开始前后,上升运动和下沉运动同时存在,为大气中垂直热交换过程提供了有利条件;(2)飑线天气过程存在垂直风的水平切变及垂直切变,反映了强烈的对流发展,发展到离地高度5000 m以上;(3)飑线天气过程存在径向速度突变增大、谱宽变宽和单波束径向速度折叠现象,说明本场出现的是风雨交加的强对流天气;(4)高空到地面存在湍流运动,能量交换频繁,气流紊乱。     

TRAMS_RUC_1 km模式初始场和侧边界方案的改进研究

本文从垂直分辨率、时间更新频率和要素完整性三个方面，对水平网格距为1 km的华南区域短时临近预报模式（TRAMS_RUC_1 km: Tropical Region Assimilation Model for South China Sea_The Rapid Update Cycle_1 km）中的初始场和侧边界方案进行改进研究。首先选择一次华南飑线个例进行敏感性试验，研究结果表明:（1）提高初始场和侧边界的垂直分辨率以后，模式对飑线内部中小尺度对流系统引起的强降水中心的模拟结果明显更加接近实况，而增加中低层的垂直分辨率对预报的改进起到了主要作用。（2）将模式侧边界时间更新频率从6 h一次提高到1 h一次以后，模式侧边界要素场的逐小时剧烈变化信息可以比较完整的保留下来。在使用高时间分辨率的侧边界条件进行模拟时，粤西沿海地区的水汽辐合明显加强，这对原来模式预报飑线移速偏慢现象会有改善作用。（3）当模式侧边界条件具有较高的时空分辨率时，进一步补充垂直速度和云微物理变量的侧边界条件对于飑线模拟结果的影响并不明显。总的来说，提高初始场和侧边界的垂直分辨率以及增加侧边界更新的时间分辨率，对于区域高分辨率模式对这次华南飑线预报效果的改进具有重要意义，而忽略垂直速度和云微物理量的侧边界条件则是一种可以接受的简化。在个例研究的基础上，利用改进后的初、边界条件进行为期一个月（2019年4月份）的批量试验，评估结果表明新方案对于逐小时降水空间分布和日变化特征的模拟均有明显改善。     

Les monchiquites de Tchircotché, vallée de la haute Bénoué (Nord du Cameroun)

Dykes of monchiquites of Cainozoic age (37.5±2.3 Ma) are intrusive in Cretaceous sandstones in the Tchircotché area, Upper Benue valley (northern Cameroon). The differentiation of the monchiquites is explained by crystal fractionation of olivine, clinopyroxene, magnetite, ilmenite and apatite. A studied rock has low Sr-isotope ratio $\text{(0.703}\text{69±10)}$, which is similar to those of the alkali basalts of the Cameroon Line. Therefore the continental crust appears to have no significant role in the genesis of the monchiquites.     

Gas permeability evolution of cataclasite and fault gouge in triaxial compression and implications for changes in fault-zone permeability structure through the earthquake cycle

We report the results of permeability measurements of fault gouge and tonalitic cataclasite from the fault zone of the Median Tectonic Line, Ohshika, central Japan, carried out during triaxial compression tests. The experiments revealed marked effects of deformation on the permeability of the specimens. Permeability of fault gouge decreases rapidly by about two orders of magnitude during initial loading and continues to decrease slowly during further inelastic deformation. The drop in permeability during initial loading is much smaller for cataclasite than for gouge, followed by abrupt increase upon failure, and the overall change in permeability correlates well with change in volumetric strain, i.e., initial, nearly elastic contraction followed by dilatancy upon the initiation of inelastic deformation towards specimen failure. If cemented cataclasite suffers deformation prior to or during an earthquake, a cataclasite zone may change into a conduit for fluid flow. Fault gouge zones, however, are unlikely to switch to very permeable zones upon the initiation of fault slip. Thus, overall permeability structure of a fault may change abruptly prior to or during earthquakes and during the interseismic period. Fault gouge and cataclasite have internal angles of friction of about 36° and 45°, respectively, as is typical for brittle rocks.     

供电线路勘测内外业一体化系统的开发和应用

供电线路勘测是属于普通工程测量,结合计算机技术制图技术和电子测绘仪器的特点,作者开发了一套适合市县一级的供电线路勘测系统,以AutoCad为绘图平台,VBA5.0为开发语言,符合测绘习惯,提高了工作效率。     

一次飑线型的多普勒雷达资料特征分析

此次飑线型弓形回波发生在高空前倾槽天气形势下,低层浅薄的水汽辐合及高空中等强度垂直切变为飑线发生发展提供了有利条件。飑线弓形回波北端具有明显的气旋性特征,飑线型弓形回波由许多小弓形回波组成,在弓形回波后部有后侧入流急流存在,弓形回波顶点中空有明显的涡旋式辐合,与弓形回波顶点相对应地面出现灾害性大风和小冰雹。飑线型弓形回波受高空WNW偏移引导气流右侧30°移动,平均移速60km/h。将2部雷达资料相结合,可以提前1h发布强对流天气预警。     

Erratum: the 2.27 day period of WR-134 (HD 191765)

The original temporal analysis of a 12 night spectral timeseries of WR-134 has been found to be flawed and a re-analysis shows that the line profile variations are indeed periodic. When combined with a 4 night timeseries taken 45 days earlier, a period near 2.27 d is found in periodograms of the Heii 5412 line centroid,rms line width, and line skew variations. When the emission line residuals are ordered as a function of phase, a sinuous feature appears to snake about the line center with an amplitude of ± 500 km s^–1. This is 20 larger than the line centroid amplitude; the calculation of which is heavily weighted by static portions of the line profile. In addition to the snake, emission residuals appear that move away from line center on unbound trajectories and are thought to result from the interaction of a periodic driver with the unstable flow of the radiation driven wind. The nature of the periodic driver is a topic for discussion.     

山洞电源、信号线路改造与接地网建设相关技术探讨

本文对铁岭地震台在山洞电源，信号线路改造与接地网建设中遇到的问题及解决的办法做简要介绍，依据洞室固有条件，结合《规范》要求，探讨了监测环境建设施工经验。