复杂战场电磁态势三维可视化研究

战场电磁环境的透明化及其态势可视化是一个急需解决的问题。分析复杂战场电磁环境可视化构建内容,针对不同军用电磁辐射特点,介绍体绘制和基于粒子系统的电磁态势可视化方法,实现地理环境和电磁环境的一体化显示,为指挥员提供及时、全面动态的电磁态势信息。     

Natural occurrence of reidite in the Xiuyan crater of China

The high‐pressure minerals of reidite and coesite have been identified in the moderately shock‐metamorphosed gneiss (shock stage II, 35–45 GPa) and the strongly shock‐metamorphosed gneiss (shock stage III, 45–55 GPa), respectively, from the polymict breccias of the Xiuyan crater, a simple impact structure 1.8 km in diameter in China. Reidite in the shock stage II gneiss displays lamellar textures developed in parental grains of zircon. The phase transformation of zircon to reidite likely corresponds to a martensitic mechanism. No coesite is found in the reidite‐bearing gneiss. The shock stage III gneiss contains abundant coesite, but no reidite is identified in the rock. Coesite occurs as acicular, dendritic, and spherulitic crystals characteristic of crystallization from shock‐produced silica melt. Zircon in the rock is mostly recrystallized. The postshock temperature in the shock stage III gneiss is too high for the preservation of reidite, whereas reidite survives in the shock stage II gneiss because of relatively low postshock temperature. Reidite does not occur together with coesite because of difference in shock‐induced temperature between the shock stage II gneiss and the shock stage III gneiss.     

Trends and variability of storminess in the Northeast Atlantic region, 1874–2007

This article builds on the previous studies on storminess conditions in the northeast North Atlantic–European region. The period of surface pressure data analyzed is extended from 1881–1998 to 1874–2007. The seasonality and regional differences of storminess conditions in this region are also explored in more detail. The results show that storminess conditions in this region have undergone substantial decadal or longer time scale fluctuations, with considerable seasonal and regional differences. The most notable differences are seen between winter and summer, and between the North Sea area and other parts of the region. In particular, winter storminess shows an unprecedented maximum in the early 1990s in the North Sea area and a steady upward trend in the northeastern part of the region, while it appears to have declined in the western part of the region. In summer, storminess appears to have declined in most parts of this region. In the transition seasons, the storminess trend is characterized by increases in the northern part of the region and decreases in the southeastern part, with increases in the north being larger in spring. In particular, the results also show that the earliest storminess maximum occurred in summer (around 1880), while the latest storminess maximum occurred in winter (in the early 1990s). Looking at the annual metrics alone (as in previous studies), one would conclude that the latest storminess maximum is at about the same level as the earliest storminess maximum, without realizing that this is comparing the highest winter storminess level with the highest summer storminess level in the period of record analyzed, while winter and summer storminess conditions have undergone very different long-term variability and trends. Also, storminess conditions in the NE Atlantic region are found to be significantly correlated with the simultaneous NAO index in all seasons but autumn. The higher the NAO index, the rougher the NE Atlantic storminess conditions, especially in winter and spring.     

Detection of external influence on trends of atmospheric storminess and northern oceans wave heights

The atmospheric storminess as inferred from geostrophic wind energy and ocean wave heights have increased in boreal winter over the past half century in the high-latitudes of the northern hemisphere (especially the northeast North Atlantic), and have decreased in more southerly northern latitudes. This study shows that these trend patterns contain a detectable response to anthropogenic and natural forcing combined. The effect of external influence is found to be strongest in the winter hemisphere, that is, in the northern hemisphere in January–March and in the southern hemisphere in July–September. However, the simulated response to anthropogenic and natural forcing combined, which was obtained directly from climate models in the case of geostrophic wind energy and indirectly via an empirical downscaling procedure in the case of ocean wave heights, is significantly weaker than the magnitude of the observed changes in these parameters.     

雷击地闪密度与雷暴日数的关系分析

根据美国卫星观测得到的我国各省区年平均总闪电资料并计算出各省区的年平均地闪密度(以下简称地闪密度);根据全国各省区220个站点的年平均雷暴日资料,按照<建筑物防雷设计规范>GB50057-94(2000年版)(以下简称<规范>)公式计算出全国各省区的地闪密度.比较两种方法得出的地闪密度,发现存在较大的差异,且不同区域差异变化很大.用单位雷暴日地闪密度概念,分析了我国各地单位雷暴日地闪密度的差异及其原因,指出单位雷暴日地闪密度能粗略反映与我国气候特征相适应的地闪密度的分布状况.进一步分析湖州市2007年人工观测和闪电定位仪观测的闪电资料,得到相同的结论.从而提出<规范>规定的地闪密度计算公式存在较大误差,应对其进行进一步的修订和完善.     

多岛屿地图上绘制气象要素等值线色块的自适应方法

结合Surfer独特的强大功能,提出一种在多岛屿地图上绘制气象要数等值线色块图的自适应方法,并将该方法应用到气象资料的自动成图领域中。针对Surfer在绘制等值线方面的各种缺陷,即不能向外白化多岛屿地图和自适应性差,给出对网格文件、白化文件、色块等级文件的制作或改进方法,再结合程序对Automation接口的调用,设计整个过程的算法框图和主要代码,以浙江省1971～2000年的气象资料为数据源,自适应地实现了在浙江省地图上的各种气象要数等值线色块图。结果表明绘制的等值线色块图具有良好的可比性,可扩展性和实用性。     

Rossby波的下游效应引发我国高影响天气的分析

对近几年和历史上著名的深槽型暴雨及台风暴雨的分析表明,欧亚高空急流中Rossby波能量频散而产生的下游发展效应,对东亚高空槽的形成与发展、登陆台风的路径与长生命史有重要的影响。如果沿急流传播的Rossby波能量使110°E附近形成深厚的低压系统或使原有西风槽发展加深,天气尺度强迫产生强上升运动则非常有利于中国东部出现暴雨过程。而当欧亚中高纬Rossby波活动的下游效应导致在40°N附近东亚地区对流层中、高层形成闭合高压,同时有西太平洋台风或热带风暴登陆中国,受大尺度环流场引导气流的影响,台风往往取西行或西北行路径。如果同时来自海上的季风涌强烈,将延长台风环流系统的生命史,产生大范围致洪暴雨。目前业务上使用的全球数值预报模式对Rossby波列的下游发展效应有一定的中期预报能力,建议在日常业务预报中关注亚洲高空急流中Rossby波能量传播过程中大形势的突变与调整。Hovmller图分析方法,是分析Rossby波列下游发展效应的一个简单、直观和有效的工具,可应用于日常业务预报分析中。     

气候场重建方法的比较——以欧洲为例

<正>1两种气候场重建方法的历史回顾温度变幅对更好地了解过去温度的演变和变化至关重要。基于古气候资料重建过去温度的变化能够深刻阐释气候的强迫作用。现有的多数重建研究均把欧洲到全球尺度的20世纪变暖置于宽泛的历史长河     

县级气象台站做好文化建设的思考

作为基层气象部门,文化建设对于一个单位强化内部管理、谋划科学发展,重塑价值体系具有重要意义。为此对基层气象台站文化建设情况开展了问卷调查,分析了基层台站气象文化建设的现状。在此基础上,探讨了气象文化的重要作用、气象文化建设的阻碍因素和气象文化建设的措施。     

2006年汛期VIC水文模型模拟结果分析

利用大尺度陆面水文模型VIC及其汇流模型模拟了2006年5-9月全国0.5°×0.5°逐日径流深和土壤相对湿度分布,对淮河流域2006年汛期(6月28日-7月5日)强降水过程期间的模拟结果进行了渍涝灾害的分析.同时对流域主要水文站逐日流量(0.5°×0.5°)过程进行了模拟,并与实况作了对比分析;并且针对淮河流域不同空间分辨率(0.5°×0.5°及0.1°×0.1°)下主要水文站点的逐日流量过程进行了比较.结果表明:VIC模型模拟的径流深和土壤相对湿度分布与降水分布是一致的,模拟土壤湿度具有可用性.利用累计降水、径流分布和土壤相对湿度及流量变化可以监测渍涝灾害的发生;VIC模型及其汇流模型在一定程度上可以反映出实际流量的变化趋势,模拟流量对降水较敏感,细网格模拟流量在量值上与实况更为接近;模拟结果误差可能跟汇流模型中流域边界的确定、参数率定、气象强迫资料等因素有关.