初值及物理过程对\

利用国防科技大学全球中期数值天气预报模式（YinHe Global Spetral model,YHGS）产品驱动WRF对2018年7月4日华中地区暴雨过程进行模拟,并与ERA-interim资料作初始场模拟结果对比,评估YHGS模式产品在此次暴雨过程预报中的应用能力。结果表明：（1）WRF-YHGS对2018年7月4日华中地区暴雨过程有一定的预报能力,其模拟的大尺度环流形势、水汽收支量变化趋势与WRF-ERA有着很好的一致性,YHGS模式产品驱动中尺度数值预报是可行的。（2）WRF-YHGS模拟效果较WRF-ERA差,但大雨量级WRF-ERA湿偏差较大,两组试验各物理量模拟结果存在一定差距,且随着积分时间的增加差异逐渐增大。（3）WRF-YHGS、WRF-ERA模拟结果的差异主要来自YHGS与ERA初始场中差异较大的次天气尺度运动和YHGS全球模式预报场误差两个方面。

     

简单热带海气耦合模型中不同扰动形式的作用

在局地热平衡情况下,将物理量先用韦伯函数展开,然后去掉相应分量的滤波方 法,讨论了简单热带海气耦合模型中不同形式扰动的作用和贡献,结果表明,在热带海气耦合 系统中,大气准定常 Ｒｏｓｓｂｙ波和海洋 Ｒｏｓｓｂｙ波对于耦合系统贡献较大,它们决定着耦合系统 与耦合扰动的性质,而大气准定常Ｋｅｌｖｉｎ波和海洋Ｋｅｌｖｉｎ波对于耦合系统贡献相对较小．     

Elasticity soltion of rupture model of shallow earthquake

Based on the theory of elastic mechanics, and using the typical rupture model of shallow earthquake, the authors considered the shallow earthquake as a plane mechanical problem, which was constructed the corresponding mechanical model. By the stress components' formulas of the semi-infinite model acted by the finite even shearing force, the main stress is deduced. It is clear that the sector on the right of the center section is squeezed zone, where the maximum principal stress points at the "source of stress", and that on the left is tensile zone, where the minimum principal stress points to the "source of stress".     

Scaling of response spectrum and duration for aftershocks

Aftershocks have the potential to cause collapse of a structure that has been already damaged by the preceding main shock. Seismic safety of a structure should therefore be ascertained through a damage analysis using the anticipated main shock and few larger-aftershock motions. Simulation of aftershock motions needs characterization of the seismic hazard due to aftershocks, and therefore it will be useful to develop a conditional scaling model that can predict the response spectrum of an anticipated aftershock motion consistent with the design spectrum of the main shock motion anticipated at the same station. In this study an attempt is made to develop a conditional scaling model for the pseudo spectral velocity spectrum via linear regression analysis on the aftershock and main shock recordings for the 1999 Chi–Chi earthquake. It is shown that it may be possible to obtain a simpler and approximate version of the conditional model from an unconditional model. Damage-causing potential of a ground motion also depends on its strong motion duration (SMD) and therefore a conditional scaling model is developed for SMD of the aftershock motion in several narrow frequency-bands. The model is developed for the larger-aftershock motions and it is shown that a reasonable replacement of such a model may be obtainable directly from an unconditional model. Finally, a simple weighted averaging scheme is proposed to obtain the composite SMD from the SMDs for different frequency bands by using the pseudo spectral acceleration spectrum of the motion.     

Crustal Growth by Magmatic Accretion Constrained by Metamorphic P-T Paths and Thermal Models of the Kohistan Arc, NW Himalayas

Magmatic accretion is potentially an important mechanism inthe growth of the continental crust and the formation of granulites.In this study, the thermal evolution of a magmatic arc in responseto magmatic accretion is modeled using numerical solutions ofthe one-dimensional heat conduction equation. The initial andboundary conditions used in the model are constrained by geologicalobservations made in the Kohistan area, NW Himalayas. Takingconsideration of the preferred intrusion locations for basalticmagmas, we consider two plausible modes of magmatic accretion:the first involves the repeated intrusion of basalt at mid-crustaldepths (‘intraplate model’), and the second evaluatesthe simultaneous intrusion of basalt and picrite at mid-crustaldepths and the base of the crust respectively (‘double-platemodel’). The results of the double-plate model accountfor both the inferred metamorphic P–T paths of the Kohistanmafic granulites and the continental geotherm determined frompeak P–T conditions observed for granulite terranes. Thedouble-plate model may be applicable as a key growth processfor the production of thick mafic lower crust in magmatic arcs. KEY WORDS: thermal model; magmatic underplating; P–T path; granulite; lower crust     

基于地质记录用时域组合模型预测气候变化趋势的初步研究

用时域分析组合模型建立了１００万年来６０°Ｎ６月份太阳辐射量时间序列、宝鸡黄土粒度时间序列、渭南夏季风指数时间序列的动态模型．研究结果表明,时域分析组合模型较好地提取了时间序列的信息,得到的几个显著周期Ｔ＝１３３,１００,８９,４１,２３,１９ｋａ,与地球轨道三要素的变化周期接近．用组合模型拟合实测数据,精度是高的;用其预测未来气候替代性指标时间序列的变化情况,发现未来气候有向干冷方向发展的趋势．时域分析组合模型为研究气候变化趋势提供了一种定量分析、预测的方法．     

基于准三维有限元方法建立的地震活动模型

基于有限元方法,参照细胞自动机模型,建立了一个地震活动演化的动力学模型.在这个模型中,根据边界条件和单元介质参数的分布,利用有限元方法确定各单元的应力增长速率.每个单元设定初始应力和摩擦因数,利用破裂准则可得到单元破裂所需时间.当单元破裂后,将破裂单元作为内部边界,利用有限元方法计算由于这个单元破裂对系统其他单元造成的应力调整.根据上述规则,建立一个由30×40个节点组成,在定常位移速率边界条件作用下的地震活动模型,探讨了区域应力场的动态演化、地震活动图像和各种参数变化对地震活动的影响.结果表明该模型在研究地震活动方面有一定优势并具有实用价值.     

雷暴探测研究的进展

基于达州市2015年10月-2016年9月的闪电定位和探空观测资料,以850 hPa与500 hPa温差、大气可降水量、K指数、对流有效位能、对流抑制和抬升指数作为雷暴预警因子,利用投影寻踪动态聚类方法对该时段内的雷暴个例构建了预警模型。结果表明：（1）模型预报结果定量评估的临界成功指数为72.00%,该模型对个例达到了识别和预警效果;（2）该预警模型与常规预警方法相比,具有识别率高,计算简便,客观性强等特点,可为雷暴预警提供了一种新的客观预报方法。

     

速度传感反馈地震计的参数稳定性分析

从理论上定量分析机械摆和环路滤波等开环诸参数变化对速度传感反馈地震计闭环参数的影响.研究指出,在环路设计中可半自由选取的开环阻尼取值对参数稳定性有重要影响.过大或过小的开环阻尼取值均可能造成参数稳定性急剧变差,影响地震计在只标不调的状况下长期连续稳定工作.     

Compositional Zoning of the Bishop Tuff

Compositional data for >400 pumice clasts, organized accordingto eruptive sequence, crystal content, and texture, providenew perspectives on eruption and pre-eruptive evolution of the>600 km³ of zoned rhyolitic magma ejected as the Bishop Tuffduring formation of Long Valley caldera. Proportions and compositionsof different pumice types are given for each ignimbrite packageand for the intercalated plinian pumice-fall layers that eruptedsynchronously. Although withdrawal of the zoned magma was lesssystematic than previously realized, the overall sequence displaystrends toward greater proportions of less evolved pumice, morecrystals (0·5–24 wt %), and higher FeTi-oxide temperatures(714–818°C). No significant hiatus took place duringthe 6 day eruption of the Bishop Tuff, nearly all of which issuedfrom an integrated, zoned, unitary reservoir. Shortly beforeeruption, however, the zoned melt-dominant portion of the chamberwas invaded by batches of disparate lower-silica rhyolite magma,poorer in crystals than most of the resident magma but slightlyhotter and richer in Ba, Sr, and Ti. Interaction with residentmagma at the deepest levels tapped promoted growth of Ti-richrims on quartz, Ba-rich rims on sanidine, and entrapment ofnear-rim melt inclusions relatively enriched in Ba and CO₂.Varied amounts of mingling, even in higher parts of the chamber,led to the dark gray and swirly crystal-poor pumices sparselypresent in all ash-flow packages. As shown by FeTi-oxide geothermometry,the zoned rhyolitic chamber was hottest where crystal-richest,rendering any model of solidification fronts at the walls orroof unlikely. The main compositional gradient (75–195ppm Rb; 0·8–2·2 ppm Ta; 71–154 ppmZr; 0·40–1·73% FeO*) existed in the melt,prior to crystallization of the phenocryst suite observed, whichincluded zircon as much as 100 kyr older than the eruption.The compositions of crystals, though themselves largely unzoned,generally reflect magma temperature and the bulk compositionalgradient, implying both that few crystals settled or were transportedfar and that the observed crystals contributed little to establishingthat gradient. Upward increases in aqueous gas and dissolvedwater, combined with the adiabatic gradient (for the 5 km depthrange tapped) and the roofward decline in liquidus temperatureof the zoned melt, prevented significant crystallization againstthe roof, consistent with dominance of crystal-poor magma earlyin the eruption and lack of any roof-rind fragments among theBishop ejecta, before or after onset of caldera collapse. Amodel of secular incremental zoning is advanced wherein numerousbatches of crystal-poor melt were released from a mush zone(many kilometers thick) that floored the accumulating rhyoliticmelt-rich body. Each batch rose to its own appropriate levelin the melt-buoyancy gradient, which was self-sustaining againstwholesale convective re-homogenization, while the thick mushzone below buffered it against disruption by the deeper (non-rhyolitic)recharge that augmented the mush zone and thermally sustainedthe whole magma chamber. Crystal–melt fractionation wasthe dominant zoning process, but it took place not principallyin the shallow melt-rich body but mostly in the pluton-scalemush zone before and during batchwise melt extraction. KEY WORDS: Bishop Tuff; ignimbrite; magma zonation; mush model; rhyolite