Impact of updraft on neutralized charge rate by lightning in thunderstorms: A simulation case study

The rate of neutralized charge by lightning (RNCL) is an important parameter indicating the intensity of lightning activity. The total charging rate (CR), the CR of one kind of polarity (e.g., negative) charge (CROP), and the outflow rate of charge on precipitation (ORCP) are proposed as key factors impacting RNCL, based on the principle of conservation of one kind of polarity charge in a thunderstorm. In this paper, the impacts of updraft on CR and CROP are analyzed by using a 3D cloud resolution model for a strong storm that occurred in Beijing on 6 september 2008. The results show that updraft both promotes and inhibits RNCL at the same time. (1) Updraft always has a positive influence on CR. The correlation coefficient between the updraft volume and CR can reach 0.96. Strengthening of the updraft facilitates strengthening of RNCL through this positive influence. (2) Strengthening of the updraft also promotes reinforcement of CROP. The correlation coefficient between the updraft volume and CROP is high (about 0.9), but this promotion restrains the strengthening of RNCL because the strengthening of CROP will, most of the time, inhibit the increasing of RNCL. (3) Additionally, increasing of ORCP depresses the strengthening of RNCL. In terms of magnitude, the peak of ORCP is equal to the peak of CR. Because precipitation mainly appears after the lightning activity finishes, the depression effect of ORCP on RNCL can be ignored during the active lightning period.     

建筑物高度对上行闪电触发以及传播影响的数值模拟

为了探讨建筑物高度对单个上行闪电触发以及传播的影响,设定了一个固定的背景电场,并结合自行触发的上行闪电随机放电参数化方案,进行了二维高分辨率上行闪电放电的模拟试验。结果表明:(1)上行闪电在初始阶段分支比较少;发展到离地面2 km左右后,闪电开始出现大量的分支,闪电通道开始出现明显的分叉:一部分通道继续向高电荷密度中心垂直传播,另一部分通道绕过高电荷密度中心,向外水平传播;模拟的上行闪电只能垂直传播到4 km处的负电荷中心,不能穿过0电势线向上方的正电荷区传播。(2)建筑物高度对上行闪电的触发起了关键作用,建筑物越高,越容易触发上行闪电。(3)建筑物高度对上行闪电传播具有一定的反作用,随着建筑物高度增高,模拟出的上行闪电的水平和垂直传播距离都有所减小,通道的分形维数变小,通道传播的总长度也逐渐减小。     

强对流天气监测预报预警技术进展

强对流天气预报业务包括监测、分析、预报、预警和检验等方面。对流初生识别、对流系统强度识别和对流天气类型识别等监测技术取得新进展,综合多源资料的监测技术已应用于中国气象局中央气象台业务。对流系统的触发、发展和维持机制等获得了新认识,我国不同类型强对流天气及其环境条件统计气候特征、分析规范及相应业务产品等为业务预报提供了必要基础和技术支撑。光流法、多尺度追踪技术以及应用模糊逻辑方法的临近预报技术等有明显进展,融合短时预报技术得到广泛应用,对流可分辨高分辨率数值 (集合) 预报及其后处理产品预报试验取得了显著成效,基于数值 (集合) 预报应用模糊逻辑方法的分类强对流天气短期预报技术为业务预报提供了技术支撑。强对流天气综合监测和多尺度自适应临近预报技术、多尺度分析技术以及融合短时预报技术、发展并应用模糊逻辑等方法的、基于高分辨率数值 (集合) 模式的区分不同强度等级和极端性的分类强对流天气精细化 (概率) 预报技术等是未来发展的主要方向。     

LD-Ⅱ和ADTD型闪电定位资料的对比分析

为了更全面地了解LD-Ⅱ和ADTD型闪电定位资料的准确性,利用安徽省2010年3—9月两套闪电定位系统监测到的资料,对比分析安徽省雷电活动规律,结果表明:两套资料在地闪总数、地闪时间变化、地闪空间分布、雷电流极性和强度等方面都存在较大的差异,LD-Ⅱ型闪电定位系统积累的资料时间较长,但ADTD型闪电定位系统在地闪空间分布、雷电流极性和强度的探测方面准确度更高.与雷灾资料对比发现,ADTD型闪电定位仪监测到的闪电记录距离受灾点较近、误差较小.     

南阳市1960—2013年高温日数变化特征及原因分析

根据国家气象信息中心气象资料室1960—2013年南阳市地面气象月报表的观测资料,采用线性回归、简单相关系数法、M-K突变检验和Morlet小波分析等方法,研究了南阳市高温日数的变化特征,结果表明:1960—2013年南阳市共出现788次高温日;出现高温日数最多的是2013年,为37天;1987年无高温日。南阳市高温日数6月份最多,占高温天气发生总次数的36.7%;9月最少,占总次数的2.2%。从1960—2013年高温日的逐年分布情况可以看出,54 a间高温日数整体呈下降趋势,倾向率为-1.59天/10a。南阳市年高温日数在20世纪70年代的降低是一突变,具体是从1971年开始。由南阳高温日数小波系数实部图可见,高温日数存在多重时间周期尺度上的嵌套复杂结构现象,包含了多个不同尺度的周期变化,南阳年高温日数变化存在3个明显的周期振荡,分别是10~12 a、26~28 a和50~51 a的尺度。从小波方差图中可以看出,12 a、28 a、50 a存在峰值,其中尺度50 a峰值最高,能量最大;其次是尺度12 a的。高温日数较多年比高温日数较少年6—8月500 h Pa平均环流场副高西伸脊点更偏西;高温日数较多年500 h Pa平均环流场更为平直,以纬向环流为主,不利于冷空气南下,因此多晴热天气。高温日数较少年环流场上华北地区波动幅度更大,冷空气和降水天气过程较多。1960—2013年5—9月降水量呈增加趋势,这也相应地减少了高温天气。1960—2013年5—9月南阳市日照时数一直处于下降趋势,日照时数的下降也使高温日数减少。     

广西大明山景区气候特点及气象指数研究

运用大明山景区3个自动站2008~2014年的资料,分析景区的气候特点,结果显示6至8月是景区降雨最密集的时段,天坪站具有明显的多雨趋势,5至9月是人体感觉最舒适的季节。大明山景区适宜旅游的天数占73%,9月和10月是大明山旅游景区最适宜旅游的月份。大明山穿衣指数春秋跨度大,春季为一至四级,秋季为二至五级;夏冬季穿衣指数跨度小,夏季为五级,冬季为一级。同月份大明山景区和南宁城区穿衣指数等级相差2~3个等级。对大明山雾凇指数的研究表明,景区雾凇主要出现在12月和1月,得出雾凇出现时气温、风速、相对湿度等气象要素的基本特征,并设计了雾凇指数,为进一步完善大明山旅游气象服务提供参考。     

基于DBBC＋Mark5B记录系统的脉冲星观测

2009年11月,云南天文台射电天文研究团组采用40m射电望远镜以及基于DBBC（Digital Base Band Conveter）和Mark5B的VLBI记录系统对PSRJ08354510和PSRJ0332＋5434进行了观测。观测选用S波段右旋圆极化信号,起始频率为2206．99MHz,总带宽为32MHz。对数据进行相干消色散和平均后,得到PSRJ0332＋5434的单脉冲图像和两颗脉冲星的平均脉冲轮廓。由平均轮廓的展宽随时间的变化关系,对脉冲星的视周期作了一定修正后,得到信噪比更高的平均轮廓图。最后对轮廓的信噪比随时间的变化作了初步分析,由此可了解整个系统在观测时的稳定性。     

Nonradial eruption of a kinking filament observed from STEREO

On 5 April 2008, a filament at the periphery of an active region was observed by the Extreme Ultraviolet Imager telescope aboard the STEREO-A spacecraft, which showed up as a prominence eruption in the field-of-view from STEREO-B. The filament at STEREO-A 304 Å was first lengthened toward a region with weak overlying magnetic field so evolved as a large-scale one consisting of bright and dark threads twisting with each other, and then the portion below the weak field underwent an eruption. Meanwhile, the corresponding STEREO-B 304 Å prominence threads exhibited a kinking structure and tilting motion, with its center deflecting from the radial direction. By using three-dimension (3D) reconstruction technology, we obtain the 3D topology for the kinked prominence when its apex arrived at 1.4 radii, from which a clockwise rotation of about 90° is found in the course of the eruption. By comparing the 3D structure with the magnetic-field configuration computed by using the Potential-Field Source-Surface (PFSS) model, it is suggested that the filament erupted against the rather weaker than stronger overlying magnetic field, which make it appear to tilt toward one side.     

虚拟天文台数据访问系统(VO-DAS)任务调度设计与实现

为解决异地、异构、海量天文数据无缝透明地统一访问,中国虚拟天文台(China-VO)研究小组自主设计并开发了一套解决方案——虚拟天文台数据访问系统(VO-DAS)。着重从执行流程、设计模式、Session机制、生命周期、资源销毁、异常处理等模块详细阐述了该系统的任务调度设计。为了验证该系统的可行性和性能,最后描述了多个天文科学范例。     

The evolution of the z distribution of normal neutron stars in the Galaxy

Under the two initial 1‐D one parameter velocity distribution forms (one is normal, the other is exponential), the z direction scale height evolution of normal neutron stars in the Galaxy is studied by numerical simulation. We do statistics for the cases at different time segments, also do statistics for the cumulative cases made of each time segment. The results show in the cumulative cases the evolution curves of the scale heights are smoother than in the each time segment, i.e., the cumulation improve the signal‐to‐noise ratio. Certainly the evolution cases are different at different Galactic disk locations, which also have very large difference from the average cases in the whole disk. In the initial stages of z evolution of normal neutron stars, after the beginning transient states, the cumulative scale heights increase linearly with time, and the cumulative scale height increasing rates have linear relationship with the initial velocity distribution parameters, which have larger fluctuation in the vicinity of the Sun than in the whole disk. We utilize the linear relationship of the cumulative scale height increasing rates vs. the initial velocity distribution parameters in the vicinity of the Sun to make comparison with the observation near the Sun. The results show if there is no magnetic decay, then the deserved initial velocity parameters are obvious lower than the present well known results from some authors; whereas if introducing magnetic decay, for the 1‐D normal case we can make consistence among concerning results using magnetic decay time values which are supported by some authors, while for the 1‐D exponential case the results show the lackness of young pulsar samples in the larger z in the vicinity of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)