基于ROSE2.0的普洱地区CINRAD/CC雷达冰雹探测算法评估及参数本地化

为提高冰雹探测算法（Hail Detection Algorithm,HDA）产品的可用性,针对2015—2020年普洱地区监测到的22次冰雹个例,利用新一代雷达业务应用软件ROSE2.0对相关雷达基数据进行回放及产品分析,以命中率、虚警率、临界成功指数为指标对HDA算法在普洱地区的识别效果进行评估并给出本地化参数配置方案。结果表明:HDA算法在普洱地区命中率接近100%,但虚警现象非常普遍,使用强冰雹概率（Probability of Severe Hail,POSH）的预警效果优于任意大小冰雹概率（Probability of Hail,POH）,且冰雹尺寸越大POSH虚警的概率越低。进一步使用模拟测评法对POSH算法的适配参数进行分析,发现正确输入降雹日当天的0 ℃层和-20 ℃层高度能有效减少POSH的虚警率及提高临界成功指数;同时使算法预测的最大冰雹直径普遍偏大的情况得到控制,其中,中小冰雹直径偏离百分比减小76.07%,改善效果显著高于大冰雹。此外,增大反射率因子及POSH阈值能有效控制虚警,但也导致漏报次数快速增加,当阈值太大时命中率明显降低,为了保证较高的命中率和临界成功指数,选择Z=50 dBz或POSH=70%为阈值能明显改善HDA算法的识别效果。     

Influence of Near Real-Time Green Vegetation Fraction Data on Numerical Weather Prediction by WRF over North China

The green vegetation fraction(GVF) can greatly influence the partitioning of surface sensible and latent heat fluxes in numerical weather prediction(NWP) models. However, the multiyear averaged monthly GVF climatology—the most commonly used representation of the vegetation state in models—cannot capture the real-time vegetation state well. In this study, a near real-time(NRT) GVF dataset generated from an 8-day composite of the normalized difference vegetation index is compared with the 10-yr averaged monthly GVF provided by the WRF model. The annual variability of the GVF over North China is examined in detail. Many differences between the two GVF datasets are found over dryland, grassland, and cropland/grassland mosaic areas. Two experiments using different GVF datasets are performed to assess the impacts of GVF on forecasts of screen-level temperature and humidity. The results show that using NRT GVF can lead to a widespread reduction of 2-m temperature forecast errors from April to October.Evaluation against in-situ observations shows that the positive impact on 2-m temperature forecasts in the morning is more distinct than that in the afternoon. Our study demonstrates that NRT GVF can provide a more realistic representation of the vegetation state, which in turn helps to improve short-range forecasts in arid and semiarid regions of North China. Moreover, our study shows that the negative effect of using NRT GVF is closely related to the initial soil moisture.     

葛洲坝至胭脂坝长江干流段江豚活动规律

长江江豚是我国一级保护野生动物,也是长江生态系统的指示性物种,其种群数量恢复情况及活动规律一直备受关注。本文选择长江宜昌段江豚活动频繁的葛洲坝下游至胭脂坝江段为研究区域,于2021年6月-2022年5月采用定点目测、水上流动监测与无人机监测相结合的方法分区监测长江江豚的游泳行为,分析长江江豚的活动规律,构建了长江江豚出水头次的零膨胀泊松回归模型,识别影响长江江豚出水头次的关键因素,建立长江江豚出水头次与各因素间的相关关系。结果表明:(1)葛洲坝至胭脂坝长江干流段监测到最大江豚出水头次为19头次,长江江豚集群规模以2~3头最为常见,占比达58.1%;长江江豚主要表现出4种行为特征,各行为占比从大到小依次为:玩耍＞休息＞摄食＞抚幼。(2)长江江豚在葛洲坝下游近坝区(A区,葛洲坝至至喜长江大桥)出水头次最多,且在秋冬季节累计出水头次多于春夏季节,冬季累计出水头次最高,达252头次。(3)长江江豚出水头次与电站下泄流量呈显著负相关;浊度增大,长江江豚出水的概率减小。本文研究结果对长江江豚生态保护策略及长江十年禁渔效果评估具有重要参考价值。     

基于连续消光特征分析的岩石薄片分析系统

连续消光是指在正交偏光显微镜下,岩石薄片随载物台旋转而发生消光强弱连续变化的现象.作为人工鉴定岩石薄片的重要依据,提取后的连续消光特征可以用于实现岩石薄片的自动分析.结合数字图像处理技术与聚类划分算法,开发出一套能够分割出孔隙、颗粒轮廓,实现颗粒类别划分,并对结果做定量分析的岩石薄片分析系统.从矿物的消光特征本质出发,...     

西安市城市资源压力与城市化水平的灰色关联分析

统计结果显示西安城市化水平的提高也伴随着城市资源压力的加大,为了找出它们之间定量的数字特征关系,运用综合评价法对西安市近15年的城市化水平进行了测度.同时,使用资源压力指数法对西安市城市资源压力进行了定量评价,最后,用灰色关联分析方法对城市资源压力指数与城市化水平的各相关因子之间的关系进行研究.结果表明,城市资源压力与最能体现城市化发展水平的"城市现代化水平"因子之间存在着极强的关联,针对这一现状,提出了缓解城市资源压力和协调加快城市化发展进程之间矛盾的几点建议.     

Geological settings and metallogenesis of high-grade iron deposits in China

The predominant types of high-grade iron deposits in China include skarn, sedimentary metamorphic(banded ironformation, BIF-type), continental/submarine volcanic-hosted and magmatic Fe-Ti-Voxide deposits. Based on a comprehensive review of current studies on these deposits, this paper suggests that the oxygen concentration in atmosphere played an important role for the formation of BIFs, whereas the tectonic setting and deep magmatic differentiation processes are more important for the other types. Notably, both high temperature and high pressure experiments and melt inclusion studies indicate that during the differentiation, high temperature magmas could develop iron-rich magma via liquid immiscibility but not pure oxide melt("iron ore magma"). Fe-P melt could be generated directly by liquid immiscibility under hydrous and oxidized condition. The formation of high-grade iron deposits is mostly associated with the processes related to multiple stages of superimposition, e.g., desiliconization and iron enrichment, removal of impurity, and remobilization and re-precipitation of iron. According to the temporal evolution, the high-grade iron deposit could be divided into multi-episode superimposition type(temporally discontinuous mineralization) and multi-stage superimposition type(temporally continuous mineralization). The former is represented by the sedimentary metamorphic iron deposit, and the latter includes those related to magmatic-hydrothermal fluids(e.g., skarn,volcanic-hosted and magmatic types).     

天津市滨海地区地面沉降灾害风险评估与区划

文章对1985~2006年累计地面沉降量及近几年地面沉降速率进行分析和叠加评价,完成天津市滨海地区地面沉降灾害危险性分区图;以人口密度和单位面积GDP为指标进行易损性分析;从每km²水准测量km数和地下水压采量占开采量百分比两方面考虑防灾减灾能力;在此基础上,借助GIS空间分析方法,将危险性分区图、易损性分区图和防灾减灾能力分区图进行叠加分析,完成天津市滨海地区地面沉降灾害风险区划图,分为低风险区、较低风险区、中等风险区、较高风险区、高风险区5等。     

巴楚-伽师6.8级地震地质灾害及未来地震地质灾害

2003年2月24日新疆巴楚—伽师交界地区发生了MS6.8地震。地震的发生除了对建筑物及构筑物与水利、交通、电力、电信设施造成了不同程度的破坏外,在地震烈度Ⅶ度以上(包括Ⅶ度)地区产生了不同程度的地震地质灾害。地震地质灾害主要为场地砂土液化、地裂缝与河流陡岸滑塌等类型。随后在新疆巴楚—伽师6.8级地震灾区开展了地震小区划工作,对Ⅶ、Ⅷ、Ⅸ度区进行了场地工程地质条件勘测与综合评价,判定该地区未来可能产生的主要地震地质灾害为场地砂土液化、河流陡岸滑塌。     

云南澜沧老厂银铜铅锌矿床地质特征及成因研究

云南澜沧老厂银铜铅锌多金属矿床为我国西南三江地区著名的多金属矿床,对该矿床的成矿地质背景、矿床地质特征、围岩蚀变特征以及矿床分带特征进行了详细的论述,对众说纷纭的矿床成因进行了总结。     

湘中南二叠系孤峰组硅质岩的成因属性及其地球动力学指示意义

华南二叠系底部的硅质岩及同一层位对应于华南重要的地幔强活动期和成矿期，有非常重要的动力学指示意义。研究表明，孤峰组剖面的岩性可划分为三段：泥页岩段、厚层状硅质岩段和薄层状硅质岩段。沿剖面自下而上，Al2O3、K2O和TiO2含量逐渐降低，MnO、TFe等组分逐渐升高；稀土元素显示出一定的铈负异常，∑REE偏低，且向上∑REE逐渐减少而HREE／LREE逐渐增高；一些热水沉积诊断性微量元素如As、Sb、Hg等也显示出一定程度的异常。这些特征均表明硅质岩的成岩过程中包含有正常沉积和热水沉积的共同作用，且自下而上热水沉积作用逐渐增强的趋势。这种成岩作用的演化特征，代表了下扬子地台拉张裂陷盆地对晚古生代伸展背景的沉积响应，对于探讨裂谷盆地阶段性发育的动力学特征有一定的指示意义。