A CASE STUDY OF FRONTAL CYCLOGENESIS AND ITS SENSITIVITY TO COASTAL INITIAL CONDITIONS

In this study,the predictability and physical processes leading to the rapid frontal cyclogenesis,that took place in the east coast of the U.S.during 3—4 October 1987,are examined using a nested-grid.mesoscale model with a fine-mesh grid size of 25km.It is shown that the model reproducesreasonably well the cyclogenesis in a coastal baroclinic zone.its subsequent deepening and movementas well as the pertinent precipitation.It is found that the frontal cyclogenesis occurs in a favorablelarge-scale environment with pronounced thermal advection in the lower troposphere and markedpotential vorticity(PV)concentration aloft associated with the tropopause depression.The transportof warm and moist air from the marine boundary layer by the low-level in-shore flow provides thenecessary energy source for the observed heavy precipitation and a variety of weather phenomenareported in the cold sector.Several 24-h sensitivity simulations are performed to examine the relative importance of diabaticheating,adiabatic dynamics and various initial conditions in the frontal cyclogenesis.It is found thatlatent heat release,even though quite intense,accounts for only 25% of the cyclone's total deepeningin this case:the weak impact seems due to the occurrence of latent heating in the cold sector and theupward lifting of the dynamical tropopause by diabatic updrafts.Vorticity budgets show that the low-level thermal advection dominates the incipient stage,whereas the vorticity advection determines therapid deepening rate at the mature stage.The results reveal that the predictability of the presentstorm is closely related to the vertical coupling between the surface cyclone and the upper-level PVcore,which is in turn determined by initial offshore perturbations in the lower troposphere.     

断层模型在火山区形变和重力反演中的应用

利用腾冲火山区1998～2002年的垂直形变和重力测量资料，应用多元Mogi模型对测区的等效岩浆房位置及大小进行了反演计算，得出了最佳拟合值。但当对形变和重力资料联合分析时却发现：实测重力数据比用球形Mogi模型计算所得的值要大得多。为了对此进行合理的解释，提出了断层模型。当岩浆沿断层上升时，充填了断层中原先存在的大量空隙．因而可以只对重力产生影响．而不对形变产生影响。为此沿断层积分得出上升岩浆所产生的重力异常，其结果与实测重力资料拟合得较好。同时断层模型也对负的岩浆源(即岩浆的流失)作出了较为合理的解释。     

ADI BAROTROPIC OCEAN MODEL FOR SIMULATON OF KUROSHIO INTRUSION INTO CHINA SOUTHEASTERN WATERS

In this numerical model for simulating the Kuroshio intrusion into the East and South China Seas,vertically averaged marine hydrodynamic equations governing ocean currents and long-period waves areapproximated by a set of two-time-level semi-implicit finite difference equations. The major terms in-cluding the local acceleration, sea-surface slope, Coriolis force and the bottom friction are approxi-mated with the Crank-Nicholson scheme, which is of second order accuracy. The advection terms are app-roximated with the Leith scheme. The difference equations are split into two sets of alternating directionimplicit quations, each of which has a tridiagonal matrix and can be easily solved. The model reproduces a major Kuroshio intrusion north of Luzon Island, one north of Taiwan Island, andone west of the Tokara Strait. The model shows a current system running from the Luzon Strait to the coastof Vietnam and Hainan Island, through the Taiwan Strait and then into the Tsushima Strait. The summerand winter monso     

典型强震动加速度仪一致性检验

针对两种典型强震动加速度仪,ETNA与MR2002,利用汶川地震强余震流动观测进行了两仪器的一致性检验.通过架设在同一仪器墩上的2种强震动加速度仪在5次余震事件中所获取加速度记录的波形、峰值、傅里叶振幅谱及反应谱的对比分析可知,ETNA仪器记录的峰值加速度与MR2002仪器记录的峰值加速度间的最大相对误差达23.6％,且南北向峰值加速度差异大于东西向和竖向,竖向明显小于两水平向;反应谱及傅里叶谱变化趋势基本相同,只是幅值存在些微差异,且竖向谱值相差最小,明显小于两水平向,反应谱最大相对误差近5％,相对于低频反应谱,高频反应谱差异较大;此外,亦存在两仪器记录时程曲线反向、记录时间长度不等、触发点不同等差异.经分析认为,这些差异主要是由于两种不同仪器性能上的微差异、仪器参数设置不同、以及触发滤波算法不同等因素引起的.     

震情信息发布平台的研制与应用

基于Android系统开发震情信息发布平台,实现实时获取中国地震局EQIM速报信息、实时获取安徽台网编目信息、拦截指定号码短信等功能,并调用百度在线地图显示震中地理信息,利用手机内置GPS或者电信运营商基站计算震中距离手机持有者的距离.     

Solar cycle distribution of major geomagnetic storms

We examine the solar cycle distribution of major geomagnetic storms (Dst ≤ -100 nT), including intense storms at the level of- 200 nT< Dst ≤-100 nT, great storms at -300 nT< Dst ≤-200 nT, and super storms at Dst ≤-300 nT, which occurred during the period of 1957-2006, based on Dst indices and smoothed monthly sunspot numbers. Statistics show that the majority (82%) of the geomagnetic storms at the level of Dst ≤-100 nT that occurred in the study period were intense geomagnetic storms, with 12.4% ranked as great storms and 5.6% as super storms. It is interesting to note that about 27% of the geomagnetic storms that occurred at all three intensity levels appeared in the ascending phase of a solar cycle, and about 73% in the descending one. Statistics also show that 76.9% of the intense storms, 79.6% of the great storms and 90.9% of the super storms occurred during the two years before a solar cycle reached its peak, or in the three years after it. The correlation between the size of a solar cycle and the percentage of major storms that occurred, during the period from two years prior to maximum to three years after it, is investigated. Finally, the properties of the multi-peak distribution for major geomagnetic storms in each solar cycle is investigated.     

地震临界丛集的判定及其应用

介绍了地震临界时间丛集的判定方法——时间结构变异诊断方法。把时间结构变异诊断方法运用于1999年岫岩地震序列及中国大陆强震活动特性研究，并按此方法预测了中国大陆未来大震可能发生的时间点。研究认为，时间结构变异诊断法不仅可以用作前震序列和余震序列以及正常震群活动的判断，同时也适用于区域地震活动状态的描述。震例研究表明，时间结构变异诊断法在地震预测中具有实际意义。     

REE and εNd of clay fractions in sediments from the eastern Pacific Ocean:Evidence for clay sources

The surface sediments from the eastern Pacific Ocean are mainly composed of biogenetic fossils, silicate detritus, ferromanganese spherolites and clay fractions. Among them, the clay fractions with grain size less than 2 μm (mainly clay minerals) are mostprevalent, especially in the non-calcareous sediments (the content of calcareous fossils is less than 5%), the clay fraction contents often exceed 70%[1―5]. Because of the influences of Antarctic Bottom Water (AABW), equatorial currents, …     

张掖市震灾预防和灾后重建工作

0前言在省委、省政府的正确领导下,在省地震局具体指导和大力支持下,张掖市政府和地震局认真贯彻“预防为主,防御与救助相结合”的防震减灾工作方针,始终把防震减灾工作当作事关人民生命财产安全、经济发展和社会稳定的大事来抓,切实加强对全市防震减灾工作的领导,狠抓震害预防     

玉门市地震宣传和应急工作

0前言甘肃省玉门市位于河西走廊西端,处在阿尔金山断裂带和祁连山北缘断裂带的交汇地带,境内地质构造复杂,历史上曾经发生过多次破坏性地震,其中包括产生广泛影响的1932年昌马7.6级大地震和2002年青西5.9级地震,近年来被中国地震局和省地震局确定为地震注意监视区。面对严峻的地震环境和震情趋势,玉门市委、市政府一直十分重视防震减灾工作,坚持以建立健全防震减灾“三大工作体系”为重点,加强领导,精心部署,狠抓落实,在防震减灾宣传和地震应急工作方面积累了一定的经验。1努力提高防震减灾宣传工作水平1.1科学规划,明确防震减灾宣传工作目…