陕西关中地区一次突发性暴雨的雷达回波特征分析

利用陕西关中地区46个自动气象站数据、NCEP/NCAR 1°×1°再分析资料、西安新一代多普勒天气雷达资料等,对2016年7月18日关中一次突发性暴雨过程进行分析。结果表明:影响此次暴雨的主要因子有西太平洋副热带高压、西北路弱冷空气、切变线、偏南和偏东风急流等。雷达图上,最强回波中心(45～55 dBz)高度在6 km以下,为低质心结构,径向速度图上零速度线呈"S"型,表示低层暖平流,风向辐合辐散和逆风区等特征均有利于短时强降水的发生。逆风区、VIL的峰值与强降水中心区、强回波中心位置有很好的对应关系。当VIL中心值在25～30 kg/m~2时,可能会出现小时雨强超过20 mm的短时强降水。这些结果对预报关中地区突发性暴雨有很好的参考意义。     

广义相当位温及其扩展应用

广义相当位温是一个包含水汽和液态水在内的新的大气热力学参量。通过简明推导和论证，进一步讨论其物理意义和扩展应用；结合耗散结构理论，提出了排熵指数的概念；根据广义相当位温自身的特点，设计了大气液态水含量指数和大气水物质含量指数等预报判据；这些参数在强对流天气和区域性暴雨分析预报中，应用效果较好。     

A land surface model incorporated with soil freeze/thaw and its application in GAME/Tibet

Land surface process is of great importance in global climate change, moisture and heat exchange in the interface of the earth and atmosphere, human impacts on the environment and eco- system, etc. Soil freeze/thaw plays an important role in cold land surface processes. In this work the diurnal freeze/thaw effects on energy partition in the context of GAME/Tibet are studied. A sophisti- cated land surface model is developed, the particular aspect of which is its physical consideration of soil freeze/thaw and vapor flux. The simultaneous water and heat transfer soil sub-model not only reflects the water flow from unfrozen zone to frozen fringe in freezing/thawing soil, but also demon- strates the change of moisture and temperature field induced by vapor flux from high temperature zone to low temperature zone, which makes the model applicable for various circumstances. The modified Picard numerical method is employed to help with the water balance and convergence of the numerical scheme. Finally, the model is applied to analyze the diurnal energy and water cycle char- acteristics over the Tibetan Plateau using the Game/Tibet datasets observed in May and July of 1998. Heat and energy transfer simulation shows that: (i) There exists a negative feedback mechanism between soil freeze/thaw and soil temperature/ground heat flux; (ii) during freezing period all three heat fluxes do not vary apparently, in spite of the fact that the negative soil temperature is higher than that not considering soil freeze; (iii) during thawing period, ground heat flux increases, and sensible heat flux decreases, but latent heat flux does not change much; and (iv) during freezing period, soil temperature decreases, though ground heat flux increases.     

The exsolution of magmatic hydrosaline chloride liquids

Hydrosaline liquid represents the most Cl-enriched volatile phase that occurs in magmas, and the exsolution of this phase has important consequences for processes of hydrothermal mineralization and for volcanic emission of Cl to the atmosphere. To understand the exsolution of hydrosaline liquids in felsic to mafic magmas, the volatile abundances and (Cl/H₂O) ratios of more than 1000 silicate melt inclusions (MI) have been compared with predicted and experimentally determined solubilities of Cl and H₂O and associated (Cl/H₂O) ratios of silicate melts that were saturated in hydrosaline chloride liquid with or without aqueous vapor in hydrothermal experiments. This approach identifies the minimum volatile contents and the values of (Cl/H₂O) at which a hydrosaline chloride liquid exsolves from any CO₂- or SO₂-poor silicate melt. Chlorine solubility is a strong function of melt composition, so it follows that Cl solubility in magmas varies with melt evolution. Computations show that the (Cl/H₂O) ratio of residual melt in evolving silicate magmas either remains constant or increases to a small extent with fractional crystallization. Consequently, the initial (Cl/H₂O) in melt that is established early during partial melting has important consequences for the exsolution of vapor, vapor plus hydrosaline liquid, or hydrosaline liquid later during the final stages of melt ascent, emplacement, and crystallization or eruption. It is demonstrated that the melt (Cl/H₂O) controls the type of volatile phase that exsolves, whereas the volatile abundances in melt control the relative timing of volatile phase exsolution (i.e., the time of earliest volatile exsolution relative to the rate of magma ascent and crystallization history).

Comparing melt inclusion compositions with experimentally determined (Cl/H₂O) ratios and corresponding volatile solubilities of hydrosaline liquid-saturated silicate melts suggests that some fractions of the eruptive, calc-alkaline dacitic magmas of the Bonnin and Izu arcs should have saturated in and exsolved hydrosaline liquid at pressures of 2000 bars. Application of these same melt inclusion data to the predicted volatile solubilities of Cu-, Au-, and Mo-mineralized, calc-alkaline porphyritic magmas suggests that the chemical evolution of dioritic magmas to more-evolved quartz monzonite compositions involves a dramatic reduction in Cl solubility that increases the probability of hydrosaline liquid exsolution. The prediction that quartz monzonite magmas should exsolve a hydrosaline chloride liquid, that is potentially mineralizing, is consistent with the general observation of metal-enriched, hypersaline fluid inclusions in the more felsic plutons of numerous porphyry copper systems. Moreover, comparing the volatile contents of melt inclusions from the potassic, alkaline magmas of Mt. Somma-Vesuvius with the predicted (Cl/H₂O) ratios of hydrosaline liquid-saturated melts having compositions similar to those of the volatile-rich, alkaline magmas associated with the orthomagmatic gold–tellurium deposits of Cripple Creek, Colorado, suggests that hydrosaline chloride liquid should have exsolved at Cripple Creek as the magmas evolved to phonolite compositions. This prediction is consistent with the well-documented role of Cl-enriched, mineralizing hydrothermal fluids at this major gold-mining district.     

潼关金矿区矿渣型泥石流熵权评价

在简述信息熵概念的基础上,对陕西潼关金矿区8条泥石流沟堆积的采矿废石量、沟谷纵坡降比等9个定量、定性调查指标进行了统计,求出各指标熵Hj、熵权Wj以及沟谷指标可能的概率值fij后,计算得出了潼关金矿区矿渣型泥石流潜势度信息熵的综合评价值;探讨了熵权评价与主观赋权评价的结果差异的原因及建议.     

祁连山区云光学特征的遥感反演与云水资源的分布特征分析

利用Terra和Aqua卫星上载的MODIS探测器接收资料和祁连山区及周边气象台站6 h降水量资料,应用6S辐射传输模式和Mie模式,针对2002—2005年以来的18次大范围云覆盖的祁连山区,反演了云的光学厚度、云粒子有效半径以及云液态含水量等参数,结合地理信息系统分析了其随海拔高度变化的分布特征及其与地面降雨量的关系.结果表明:祁连山区云的光学厚度、云粒子有效半径以及云液态含水量分布受地形影响具有显著的地域差异,最大值分布在海拔4 300 m以下的山区,是云水资源丰富区和易降水区;云宏观特征参数与地面6 h降水量成正相关关系,产生降水概率较大的云光学厚度在8~20之间,云粒子有效半径在6~12μm之间,云液态含水量在0.04 g·m^-3就能产生降水.祁连山区云液态含水量可高达0.15 g·m^-3,表明山区云水资源具有很大的开发潜力.     

液态二氧化碳洗井工艺应用与效果

应用液态 CO_2洗井,是清洗深井的一项洗井新技术。本文介绍液态 CO_2洗井原理、方法、工艺与注意事项,并以实例论述清洗深井的效果。     

阿尔泰可可托海3号脉花岗伟晶岩侵位机制、熔-流体演化、稀有金属富集机理及待解之谜

新疆阿尔泰可可托海3号脉以独特的实心礼帽形态、完美的同心环状结构分带和复杂的稀有金属矿化组合闻名于世,是我国最重要的稀有金属矿床之一。可可托海3号脉伟晶岩岩浆具有不均一性和高度演化特征。伟晶岩岩浆沿缓倾斜节理上侵,在周缘断裂的帮助下通过岩浆顶蚀形成实心礼帽形态。岩浆就位后经历了岩浆阶段、岩浆-热液阶段和热液阶段,分别伴随Be-Nb-Ta、Li-Be-Nb-Ta和Ta-Cs-Rb-Hf矿化。结晶分异作用和液相不混溶控制着3号脉的稀有金属富集和沉淀序列,流体交代可影响稀有金属再分配。外部带(Ⅰ～Ⅳ带)的强烈结晶分异过程和发生于Ⅳ带与Ⅴ带间的流体大规模出溶,有利于岩浆达到锂饱和浓度,开始锂的大规模沉淀。指出熔-流体演化过程的精细刻画、稀有金属成矿机理的进一步解析、岩浆成因的深入探讨、挥发分P、F、B、Li和CO₂对稀有金属成矿的影响以及缓倾斜帽沿深部找矿为未来研究方向。     

液塑限联合测定法的若干问题探讨

对液塑限联合测定法数据进行整理,采用基于EXCEL图表处理功能编制的电子表格计算法代替规范作图法,既方便又提高工效。同时对上海滨海平原区土层的液塑限试验合格品的临界相关系数平方值R2进行了探讨,并结合实践分析了上海滨海平原区土层的液塑限相关系数特点。     

地下水^32硅年龄的测定方法—液体闪烁计数法

用Fe(OH) 3共沉淀从天然水中提取纯化SiO2 ,回收率在 30 %～ 98% ,然后提取32 P ,将H3PO4溶液和PicoflourLLT混合制备计数溶液 ,用液体闪烁计数法测量32 P的放射性 ,计算32 Si的放射性浓度 ,最后确定地下水的年龄。通过对河北平原浅层地下水的32 Si年龄进行测定 ,所得的32 Si年龄为 92 9 89a± 1 7 87a,与1 4 C的校正年龄一致