台风路径突变诊断预报方法与1994年试用结果   总被引：3，自引：0，他引：3  

贺忠  胡斯团  张儒林 《气象》1995,21(8):7-12

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较小尺度涡旋与台风的相互作用及其对台风路径的影响   总被引：2，自引：0，他引：2  

马镜娴  刘晓东 《南京气象学院学报》1995,18(2):187-191

用一个准地转正压模式实施５组积分时间为５天的试验，研究台风环流与较小尺度涡旋之间的相互作用。结果指出，涡旋相互作用可以改变台风环流的非对称结构，进而引起台风移动偏离正常路径。  相似文献   

关于大型超大型矿床的概念问题     

沈永和 《华北地质矿产杂志》1995,10(2):236-242

关于大型超大型矿床的概念，当前还存在着不同的理解和认识，为例于国际对比和协同攻关，作者对有关问题提出：简化分级，统一名称和推行国际国内双轨制，根据成矿的普遍性和特殊性与具体地质条件相结合的原则，建议因地制宜处理好个体与群体，“有兄弟”与“独生子”、单一类型与复杂类型，贫矿与富矿，以有点，线，面的分布形式等问题。  相似文献   

2019年影响中国台风的降水预报误差及其来源研究     

何斌  喻自凤  王海平 《气象》2023,49(11):1299-1314

针对2019年影响中国的8个台风,利用面向降水对象的CRA(contiguous rain area)方法研究了欧洲中期天气预报中心确定性预报的降水误差来源,及其在不同预报时段和降水量级下的变化趋势,分析了台风路径预报误差与降水对象的CRA位置误差之间的相关性,对比计算了台风路径修正与CRA shifting方法对于改进降水预报的作用,并评估了台风降水概率分布、径向分布和非对称分布的预报误差。结果表明:总体而言,台风降水预报的主要误差来自于位置误差和形态误差;除特大量级降水以外,台风降水对象的CRA位置误差与路径误差显著相关,通过修正台风路径能改进降水预报,但其效果要逊于CRA shifting方法;预报的台风降水概率密度分布形态与观测总体上较为一致,但台风核心区内的预报降水强度均大于观测;台风登陆或靠近我国沿海前后,预报降水较观测更靠近台风中心,且略滞后于观测,预报降水的非对称性明显弱于观测。  相似文献   

The effect of the large-scale mantle flow field on the Iceland hotspot track     

Peter Mihalffy  Bernhard Steinberger  Harro Schmeling 《Tectonophysics》2008,447(1-4):5

Fluid dynamical simulations were carried out in order to investigate the effect of the large-scale mantle flow field and the depth of the plume source on the structure of the Iceland plume through time. The time-dependent location and shape of the plume in the Earth's mantle was calculated in a global model and it was refined in the upper mantle using a 3D Cartesian model box. Global flow was computed based on density heterogeneities derived from seismic tomography. Plate motion history served as a velocity boundary condition in both models. Hotspot tracks of the plume conduits and the plume head were calculated and compared to actual bathymetry of the North Atlantic. If a plume source in the lowermost mantle is assumed, the calculated surface position of the plume conduit has a southward component of motion due to southward flow in the lower mantle. Depending on tomography model, assumed plume age and buoyancy the southward component is more or less dominating. Plume models having a source at the 660 km discontinuity are only influenced by flow in the upper mantle and transition zone and hence rather yield westward hotspot motion. Many whole-mantle plume models result in a V-shaped track, which does not match the straight Greenland–Iceland–Faroe ridge. Models without strong southward motion, such as for a plume source at 660 km depth, match actual bathymetry better. Plume tracks were calculated from both plume conduits and plume heads. A plume head of 120 K anomalous temperature gives the best match between plume head track and bathymetry.  相似文献   

依连哈比尔尕山和博格达山中新生代隆升的时空分异:裂变径迹热年代学的证据   总被引：2，自引：2，他引：0  

沈传波  梅廉夫  张士万  刘麟  汤济广  周锋  严淑澜  骆吉春 《矿物岩石》2008,28(2):63-70

依连哈比尔尕山和博格达山同属于北天山构造带,它们的裂变径迹测年证据表明,依连哈比尔尕山于134 Ma～118 Ma开始隆升,中生代以来经历了5期隆升过程:134.1 Ma～118.6 Ma,68.2 Ma～65.5 Ma,37.1 Ma～36.2 Ma,23.8 Ma和9.8 Ma;博格达山于152 Ma～106 Ma开始隆升,中生代以来经历了4期隆升过程:152.3 Ma～106.3Ma.65 Ma.43.9 Ma～42.6 Ma和25 Ma.博格达山磷灰石裂变径迹年龄与样品高程具正相关性,依连哈比尔尕山磷灰石裂变径迹年龄与样品高程具负相关性.中新生代隆升年代学及隆升机制在区域小尺度上具有明显的差异.对比北天山中尺度以及整个天山大尺度上中新生代、特别是65 Ma以来的隆升和演化在时间和空间上同样具有明显的分异性.导致这种时空分异的原因一方面是印度板块与欧亚板块碰撞的远程挤压效应的动力诱导,更主要的原因可能与天山造山带不同区域深部(地幔和地壳)特定条件下的差异性活动、热一流变学性质的差异性以及不同构造边界活动的差异性有关.  相似文献   

矿床变化与保存研究的裂变径迹新途径   总被引：3，自引：0，他引：3  

王建平  翟裕生  刘家军  柳振江  刘俊 《地球科学进展》2008,23(4):421-427

矿床形成后的变化与保存是矿床学研究与找矿勘探中一项极其重要但仍需进一步加强的基础性工作。影响矿床变化与保存的众多因素中,区域隆升与剥蚀是最为关键的因素之一。裂变径迹法是研究区域隆升与剥蚀的一种有效手段,它能为我们提供剥蚀速率以及剥蚀量的定量数据。一些产于花岗质岩体内与岩体有成因联系的矿床,其成矿深度可以通过详细的流体包裹体研究来获得。通过成矿深度与岩体剥蚀深度对比分析,能使我们更好地了解矿床形成后变化保存条件。裂变径迹法与流体包裹体研究相结合是矿床形成后变化与保存研究一种切实可行的方法。  相似文献   

Experimental effects of pressure and fluorine on apatite saturation in mafic magmas, with reference to layered intrusions and massif anorthosites   总被引：1，自引：0，他引：1  

N. Tollari  D. R. Baker  S.-J. Barnes 《Contributions to Mineralogy and Petrology》2008,156(2):161-175

Apatite is a cumulate phase in the upper parts of some mafic layered intrusions and anorthositic complexes. We investigated the effect of pressure and fluorine on apatite saturation in mafic magmas to better understand under which conditions this mineral crystallizes. Apatite saturation gives information about the formation of silicate rocks, and is of interest in explaining the formation of apatite–oxide-rich rocks (e.g. nelsonites comprising approximately, one-third apatite and two-third Fe–Ti oxide). Two models of formation are proposed for this rock type: crystal fractionation followed by accumulation of apatite and Fe–Ti oxides and liquid immiscibility. New experiments carried out with mafic compositions at 500 MPa confirm that the most important variables on phosphate saturation are SiO₂ and CaO. Fluorine addition leads to apatite saturation at lower SiO₂ and higher CaO concentrations. Comparison of our results with those of previous experimental studies on liquid–liquid immiscibility at upper-to-mid-crustal conditions allows us to investigate the relative importance of apatite saturation versus liquid–liquid immiscibility in the petrogenesis of nelsonites and similar rocks. The liquid line of descent of three natural examples studied (the Sept-Îles intrusive suite, the anorthositic Complex of the Lac-St-Jean and the Skaergaard layered intrusion) do not cross the liquid–liquid immiscibility field before they reach apatite saturation. Thus, the apatite–oxide-rich rock associated with these three intrusive suites are best explained by crystal fractionation followed by accumulation of apatite and Fe–Ti oxides.  相似文献   

Modelling the formation of fission tracks in apatite minerals using molecular dynamics simulations     

J. A. L. Rabone  A. Carter  A. J. Hurford  N. H. de Leeuw 《Physics and Chemistry of Minerals》2008,35(10):583-596

We introduce a simple method to simulate the “ion explosion spike” mechanism of fission track formation within the framework of classical molecular dynamics. The method is applied to six apatite compositions and the resulting tracks are compared with each other as well as with the damage produced by another mechanism—the “Displacement spike”. In contrast to experimentally observed tracks, the radii of simulated tracks are not dependent on their direction in the crystal. Since the simulations model accurately the elastic response of apatites, this suggests that the experimentally observed difference in track radii for tracks along different crystal directions is not entirely caused by anisotropy in the elasticity of apatite. We suggest that anisotropy in the interactions between the electric fields of fission fragments and the crystal ions is a major factor in the final radii of fission tracks. In fluorapatite, the simulations also reveal the formation of small clusters of fluorite-like material in the core of the fission track, a phenomenon which has yet to be confirmed experimentally.

J. A. L. RaboneEmail:

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伊犁盆地南缘隆升剥蚀及其盆地南部的沉积响应——利用磷灰石裂变径迹分析   总被引：2，自引：0，他引：2  

韩效忠  李胜祥  蔡煜琦  郑恩玖  陈正乐  张字龙  刘权 《岩石学报》2008,24(10)

分析了伊犁盆地南缘蚀源区14件磷灰石样品,其中南缘中西部10件,东部4件。磷灰石裂变径迹表观年龄及其与高程的关系、单颗粒年龄、封闭径迹分布特征表明,伊犁盆地南缘样品均遭受了不同程度的退火,但没有发生明显的区域性热事件。通过封闭径迹正演热史模拟得出,伊犁盆地南缘中新生代构造演化经历了三叠纪-侏罗纪晚期快速隆升,白垩纪-古近纪相对稳定和新构造快速隆升三个阶段。东西两段略有不同,西段隆升时间较早,样品所在地在早三叠世就开始强烈隆升,说明当时该处离原型盆地边界较近,而东段此时样品所在位置还可能接受沉积,直至中侏罗世末期才开始隆升剥蚀。侏罗纪原型盆地南部边界至少跨过大板煤矿,因为在该处出露中侏罗世西山窑组残留地层。相应的稳定阶段东段要滞后一些,稳定时间相对较短,西段该时段长达100Ma,而东段多在50～60Ma。新构造运动强烈活动的时间东段相对较早,局部地段在38Ma就开始隆升。盆地南缘沉积相带的发育特征和新近纪（或第四纪）内给出的电子自旋共振年龄（ESR）均说明,沉积对构造具明显的响应,盆缘快速隆升阶段其盆地内相应的沉积物较粗,相对稳定阶段对应的沉积较细或缺失。  相似文献