Observational and model studies of synoptic current fluctuations in the Bohai Strait on the Chinese continental shelf

Ocean Dynamics - Three winter storms struck the Bohai and Yellow seas in succession during February 16–25, 2017. Periodic fluctuations of sea level, currents, temperature, and salinity were...     

The importance of aspect for modelling the hydrological response in a glacier catchment in Central Asia

Understanding how explicit consideration of topographic information influences hydrological model performance and upscaling in glacier dominated catchments remains underexplored. In this study, the Urumqi glacier no. 1 catchment in northwest China, with 52% of the area covered by glaciers, was selected as study site. A conceptual glacier‐hydrological model was developed and tested to systematically, simultaneously, and robustly reproduce the hydrograph, separate the discharge into contributions from glacier and nonglacier parts of the catchment, and establish estimates of the annual glacier mass balance, the annual equilibrium line altitude, and the daily catchment snow water equivalent. This was done by extending and adapting a recently proposed landscape‐based semidistributed conceptual hydrological model (FLEX‐Topo) to represent glacier and snowmelt processes. The adapted model, FLEX^G, allows to explicitly account for the influence of topography, that is, elevation and aspect, on the distribution of temperature and precipitation and thus on melt dynamics. It is shown that the model can not only reproduce long‐term runoff observations but also variations in glacier and snow cover. Furthermore, FLEX^G was successfully transferred and up‐scaled to a larger catchment exclusively by adjusting the areal proportions of elevation and aspect without the need for further calibration. This underlines the value of topographic information to meaningfully represent the dominant hydrological processes in the region and is further exacerbated by comparing the model to a model formulation that does not account for differences in aspect (FLEX^G,nA) and which, in spite of satisfactorily reproducing the observed hydrograph, does not capture the influence of spatial variability of snow and ice, which as a consequence reduces model transferability. This highlights the importance of accounting for topography and landscape heterogeneity in conceptual hydrological models in mountainous and snow‐, and glacier‐dominated regions.     

Development of the Multipurpose Timing Instrument Based on BDS

With the increasingly high requirement of clock source accuracy for seismic data servers and equipment, the development of a multipurpose timing system is urgently needed in the seismic industry. We have developed low-cost timing equipment according to the actual earthquake industry situation. This set of timing equipment can provide a unified solution to the different environment and different earthquake instruments with different timing precision demands.     

大跨桥梁结构损伤诊断与安全评估的多尺度有限元模拟研究

探讨了以结构损伤诊断与安全评估为目标的大跨桥梁结构多尺度有限元模拟的策略与方案。在有限元模型误差来源分析的基础上,提出了大跨桥梁结构模型误差的分层次修正方法。通过对润扬长江大桥斜拉桥的有限元建模和模型修正过程,提出了大跨斜拉桥结构以损伤诊断与安全评估为目标的多尺度有限元模拟方法。研究表明,大跨桥梁结构的多尺度有限元模拟必须建立在模型误差分析的基础上,并采用模型误差的分层次修正方法才能较好的满足多尺度有限元模拟的技术要求。     

利用ADSL modem的路由功能组建小型局域网

概述了琼中基准地震台利用ADSL modem的路由功能组建小型局域网的情况,这种局域网运行稳定,便于维护和管理,很适合地震台站的工作管理模式。     

长周期地震动三维有限元数值模拟方法

采用数值方法对长周期地震动进行模拟已成为当前强地面运动预测的研究方向之一。本文提出了一种有限元并行计算的高效地震动数值模拟方法,可以同时考虑震源、传播途径和场地条件对地震动的影响,并根据昆明地区未来可能发生的设定地震对昆明市的影响地震动进行了预测。这一方法可以应用于国内已探测的发震活断层进行地震危害性评价工作。     

基于阈值方法原理的江淮地区降水特性研究

利用江淮地区20个代表站点雨量计连续30年(1980—2009年)的逐日降水资料,基于阈值方法原理对该地区降水特性进行了研究,主要讨论了月平均日降水量与阈值为0.1,1.0,5.0,10.0,24.0,48.0mm/d时降水日数占该月天数比例之间的关系。研究结果表明:各站点及江淮整体月平均日降水量与超过某一阈值降水日数占该月天数的比例之间存在着高度的线性相关关系,相关性随着阈值的不同而变化,在阈值为24.0mm/d时相关性最好,相关系数普遍超过0.97。低阈值时存在着非线性相关。阈值方法具有很多方面的应用,例如能更好地理解降水的形成机制;寻求更好的估测降水的算法;发展更优的数值预报模式的参数化方案;检验各种数值预报模式降水产品等。     

安全射界图技术在人工影响天气指挥系统中的应用

为了进一步提高人工影响天气作业的安全性,利用雷达回波外推TREC、TITAN技术和安全射界图技术,生成人工影响天气预警产品、建议产品。利用雷达外推30min、60min产品与作业点最大射程的位置关系,输出作业预警产品。利用当前回波与作业点的位置关系,生成对空射击的仰角、方位角信息,利用安全射界技术进行筛选,生成实时、客观的作业建议产品,以此进行决策指挥,避免了人工决策安全射区可能出现的误差,达到了安全、高效作业的目的。     

几种降水集成预报方法的对比分析

采用多数表决集成法、评分权重集成法、多元回归集成法对承德市两来系统形成的降水进行晴雨和分级集成预报试验.结果表明:在每种单一的数值预报方法TS值均较高,总体预报质量相差不大的情况下,多数表决集中集成法可大幅度提高预报准确率;如果几种数值预报对于降水分级预报的预报准确率相差较大时,可采用评分权重集成法来提高总体预报质量;在样本足够的条件下,细化的预报结果多元回归集成法是晴雨预报和分级降水预报中比较可行的集成方法之一.     

揭阳市高温天气的气候背景特征及其成因

对1966～2006年揭阳市日极端最高气温大于等于35℃的高温天气进行统计分析,得出了高温灾害天气的气候特征,并概括出造成揭阳市高温灾害天气的成因以及环流形势.结果表明:揭阳市高温天气具有明显的时间变化,20世纪90年代以前是偏少期,1990～1997年为平均线附近平稳变化期,1998以来为明显偏多期,而且强度也是呈明显上升的趋势,这与全球气候变暖和城市热岛效应的大背景有密切的关系.同时也与区域大气环流异常有关,造成揭阳市高温天气的主要天气系统是西太平洋副热带高压和热带气旋西北气流的增温作用,前者容易造成持续性的高温天气,后者则容易造成极端最高气温.