2005年3月云南倒春寒天气的成因分析   总被引：2，自引：0，他引：2  

周国莲  普贵明  李磊  高敏琪 《气象》2006,32(12):82-87

利用2005年3月3—6日的MICAPS常规资料，对天气形势和物理量场进行了详细分析，结果表明：在这次强倒春寒天气过程中，由于孟加拉湾到中南半岛一直维持强的高压环流，高压中心在高、中、低层都达到相当的强度，致使冷空气由北向南侵入滇中后受南部高压脊阻挡未能南下，而是向西侵入滇西、滇西北。这次倒春寒天气过程虽然没有南支槽配合，但高原南侧的低槽为这次降雪降雨提供了充足的水汽；500hPa上的西北气流，为这次倒春寒带来了强的冷平流；700hPa维持在丽江、昆明、蒙自的切变线是雪雨天气持续的主要动力因子。这些工作为今后此类特殊的倒春寒天气的预报提供参考依据。  相似文献   

地下水封石洞油库地质灾害危险性评估——以山东某地下水封石洞油库工程为例     

陈奇  武强  李俊彦 《中国地质灾害与防治学报》2006,17(4):138-141,148

根据地下水封石洞油库的工程特点,分析了此类工程建设场地地质灾害类型。列举了工程场地可能存在的现状地质灾害、施工期地质灾害和运营期地质灾害。认为该类工程的地质灾害危险性评估应更关注地下地质灾害,尤其是岩爆灾害。以某地下水封石洞油库实际工程为例,说明岩爆灾害宏观预测评估应针对岩性和地应力两个主要因素。探讨了地质灾害预测评估的可靠性问题,指出预测评估的可靠性基于分析思路的正确和预测指标的合理选取。  相似文献   

小型多功能生态氡室的设计与研制     

张丽娇  张松川  刘庆成 《铀矿地质》2006,22(5):311-314

本文介绍了智能型测氡仪器标定装置——HD 5型多功能生态氡室的结构及氡浓度定值的计量过程,并分析了该氡室的性能指标。  相似文献   

云南春季低温标准的研究   总被引：8，自引：4，他引：4  

段旭  王恒康  董谢琼 《气象》1998,24(9):16-20

在参考了国内许多文献针对各地农业提出的不同的低温冷害指标和经过大量的统计分析的基础上,根据实际业务需要提出了新的云南春季低温标准,并与旧标准中的“倒春寒”和晚霜冻指标进行了对比分析。  相似文献   

Isolating and identifying atmospheric ice-nucleating aerosols: a new technique     

S. M. Kreidenweis  Y. Chen  D. C. Rogers  P. J. DeMott 《Atmospheric Research》1998,46(3-4)

Laboratory studies examined two key aspects of the performance of a continuous-flow diffusion chamber (CFD) instrument that detects ice nuclei (IN) concentrations in air samples: separating IN from non-IN, and collecting IN aerosols to determine chemical composition. In the first study, submicron AgI IN particles were mixed in a sample stream with submicron non-IN salt particles, and the sample stream was processed in the CFD at −19°C and 23% supersaturation with respect to ice. Examination of the residual particles from crystals nucleated in the CFD confirmed that only AgI particles served as IN in the mixed stream. The second study applied this technique to separate and analyze IN and non-IN particles in a natural air sample. Energy-dispersive X-ray analyses (EDS) of the elemental composition of selected particles from the IN and non-IN fractions in ambient air showed chemical differences: Si and Ca were present in both, but S, Fe and K were also detected in the non-IN fraction.  相似文献   

The 10 ka multiple vent pyroclastic eruption sequence at Tongariro Volcanic Centre, Taupo Volcanic Zone, New Zealand: Part 2. Petrological insights into magma storage and transport during regional extension     

Mitsuhiro Nakagawa  Ian A Nairn  Tetsuo Kobayashi   《Journal of Volcanology and Geothermal Research》1998,86(1-4)

The six eruption episodes of the 10 ka Pahoka–Mangamate (PM) sequence (see companion paper) occurred over a ?200–400-year period from a 15-km-long zone of multiple vents within the Tongariro Volcanic Centre (TgVC), located at the southern end of the Taupo Volcanic Zone (TVZ). Most TgVC eruptives are plagioclase-dominant pyroxene andesites and dacites, with strongly porphyritic textures indicating their derivation from magmas that ascended slowly and stagnated at shallow depths. In contrast, the PM pyroclastic eruptives show petrographic features (presence of phenocrystic and groundmass hornblende, and the coexistence of olivine and augite without plagioclase during crystallisation of phenocrysts and microphenocrysts) which suggest that their crystallisation occurred at depth. Depths exceeding 8 km are indicated for the dacitic magmas, and >20 km for the andesitic and basaltic andesitic magmas. Other petrographic features (aphyric nature, lack of reaction rims around hornblende, and the common occurrence of skeletal microphenocrystic to groundmass olivine in the andesites and basaltic andesites) suggest the PM magmas ascended rapidly immediately prior to their eruption, without any significant stagnation at shallow depths in the crust. The PM eruptives show three distinct linear trends in many oxide–oxide diagrams, suggesting geochemical division of the six episodes into three chronologically-sequential groups, early, middle and late. Disequilibrium features on a variety of scales (banded pumice, heterogeneous glassy matrix and presence of reversely zoned phenocrysts) suggest that each group contains the mixing products of two end-member magmas. Both of these end-member magmas are clearly different in each of the three groups, showing that the PM magma system was completely renewed at least three times during the eruption sequence. Minor compositional diversity within the eruptives of each group also allows the PM magmas to be distinguished in terms of their source vents. Because petrography suggests that the PM magmas did not stagnate at shallow levels during their ascent, the minor diversity in magmas from different vents indicates that magmas ascended from depth through separate conduits/dikes to erupt at different vents either simultaneously or sequentially. These unique modes of magma transport and eruption support the inferred simultaneous or sequential tapping of small separate magma bodies by regional rifting in the southern Taupo Volcanic Zone during the PM eruption sequence (see companion paper).  相似文献   

江西德兴银山火山岩-次火山岩 带状岩浆房初步研究     

叶松  莫宣学 《地球科学》1998,23(3):88

银山地区火山岩－次火山岩由流纹岩、流纹英安斑岩、英安质熔岩、英安斑岩和粗面安山斑岩组成,喷发和侵入存在着反序特征．通过各种物理化学方法确定了岩浆房中存在的化学成分和温度、密度、粘度梯度．建立了以英安质岩浆为主,顶部有一层富ＳｉＯ２、富Ｋ的流纹质岩浆,底部为少量粗面安山质岩浆的带状岩浆房．岩浆演化及带状岩浆房的形成是分离结晶、同化混染、岩浆对流和边界层机制共同作用的结果．  相似文献   

The role of modelling in geochemical engineering—a (re)view     

P. F. M. van Gaans 《Journal of Geochemical Exploration》1998,62(1-3)

Modelling is an indispensable tool in geochemical engineering in predicting the outcome of our intended interferences in geochemical systems. Because such systems are highly complex, investigation by means of designed experiment can only apply to subsystems and processes. Models too can only capture a partial, simplified image of the true system. Conceptual models play a vital role. Advantages of the use of models are, a.o., better testing of our understanding of geochemical processes, better formulation of this understanding, and better prediction of the outcome of our conjectures. Examples from hydrogeochemistry are discussed to demonstrate this.  相似文献   

A Note on Extension Variances in IR²     

Joël Chaduf  Chris Moran  Michel Goulard 《Mathematical Geology》1998,30(6):575-587

Matheron (1971) proposed an approximation of the extension variance in IR. We propose in this note an extension of this formula in IR ² , based on a MacLaurin formula. Its application is shown in an example, the estimation of the maximum depressional storage of a soil surface.  相似文献   

地质资料图文光盘存储检索系统简介     

刘金梅 《安徽地质》1998,(2)

有史以来,地质资料以纸质载体存储,以原始手工操作检索。为改变这一现状,地矿部推广的“地质资料图文光盘存储检索系统”,可实现地质资料管理现代化  相似文献