利用TOPEX卫星高度计资料分析台湾岛周边海域巨浪和大风特征     

谢辛  李燕初  许德伟  郑凌虹  林明森 《海洋学报》2009,31(5):1-9

卫星高度计实现了对全球性或区域性的海洋参量的实时监测,TOPEX卫星高度计提供了迄今为止时间序列最长、数据质量最高的全球海面风速和有效波高的同步观测资料。利用TOPEX卫星高度计资料,分析了有效波高4m以上的巨浪在台湾岛周边海域的时空分布特征,结果表明台湾岛周边海域巨浪的分布具有明显的季节特征。每年平均有效波高最大值大多数出现在夏季,春季是1a中有效波高最小的季节,而秋季和冬季是巨浪出现频率最高的季节。波高大于6m的巨浪大都出现在台湾岛东部及东北部海域,在南部海域出现较少。  相似文献   

河北省数字地震台网子台地动噪声分析   总被引：4，自引：0，他引：4  

孙晴  张新东  张双凤  闫俊岗 《华北地震科学》2007,25(2):51-54

通过对河北省数字遥测地震台网子台地动噪声分析,各个子台的台址环境和观测仪器的性能基本优良,能够适应宽频带地震观测要求。由于子台受当地经济发展、城市规模扩大以及交通建设等影响,部分台址观测条件受到影响。可以有针对性地对部分台站进行环境改造,为地震监测预报创造更好条件。  相似文献   

60年距离测量的演变   总被引：1，自引：0，他引：1  

刘基余 《海洋测绘》2010,30(2):74-78

新中国成立60年来,距离测量方法所发生的巨大变化是,20世纪50年代末期,光速测距仪和微波测距仪的推广应用,开创了"量距不用尺"的新时代;20世纪60年代中期,测地型激光测距仪的快速发展,将光波测距推向了高精度远测程的新境界;几乎与此同时,卫星激光测距和甚长基线射电干涉测量技术的测地实用化,使得测地工作者能够测量远达数千千米的站间距离;20世纪80年代初期,GPS卫星测量技术的问世,使得测地工作者步入了快速高效"量距不见站"的新天地。距离测量的这种演变,也是测绘科学技术进步的一大缩影。  相似文献   

速度传感反馈地震计的动态范围上限     

饶文松  杨晓源 《地震地磁观测与研究》2007,28(5):63-70

在开环参数一定的条件下,速度传感反馈地震计中的环路滤波是影响地震计主要技术指标的关键环节之一.本文探讨了一阶极点高通、一阶极点低通、一阶零点高通、双一阶和零阶环路滤波在扩展地震计动态范围上限方面的优缺点.研究指出,对于用闭环反馈直接生成主导二阶极点的速度传感反馈地震计,一阶零点高通环路滤波的优点较多;若允许在环外生成主导二阶极点,则零阶环路滤波也不失为一个较好的方案.  相似文献   

Very quiet intervals of geomagnetic activity and the solar wind structure     

Jaroslava Hruska  Antonin Hruska 《Pure and Applied Geophysics》1989,131(3):343-355

Extended periods of very low geomagnetic activity as described by very quiet intervals (VQI's) occur only at those times when the solar wind velocityV has a generally decreasing trend, i.e., they mainly occur either after the velocity peak of a high speed solar stream has passed the Earth, or at times when the Earth is immersed in a low speed solar plasma provided that the daily mean value ofdV/dt is negative. The VQI's most frequently start whendV/dt<0 anddB _Z/dt>0 (B _Z is the geocentric solar magnetrospheric-GSMZ-component of the IMF) and end most likely whendV/dt>0 anddB _Z/dt<0. The temporal trends of the solar wind (SW) velocity affect the variation of thea _p index only when the level of geomagnetic activity is generally low.It is suggested that a gradual expansion or contraction of the magnetosphere, associated with a slow variation of the SW pressure, plays a role in the modification of the reconnection-driven magnetohydrodynamic (MHD) fluctuations in the magnetosphere.  相似文献   

Variscan very low-grade metamorphism in southwest England: a diastathermal and thrust-related origin   总被引：2，自引：0，他引：2  

L. N. WARR  T. J. PRIMMER  D. ROBINSON 《Journal of Metamorphic Geology》1991,9(6):751-764

Abstract Regional metamorphism in the external Variscides of southwest England varied from diagenetic level to greenschist facies. There is a fundamental difference in the metamorphic character between the northern and southern regions of the area. In the north, M1 metamorphism is of a sedimentary burial character associated with high heat flow, whilst to the south it is related to tectonic burial during thrust thickening processes, with lower geothermal gradients. This pattern appears to be related to the character of basin development and its subsequent tectonic evolution. The northern region has features that accord with a diastathermal (extensional) origin for the very low-grade metamorphism whilst in the southern region the very low-grade metamorphism is linked to thrusting as a consequence of Variscan compression. The Tintagel High-Strain Zone presents an anomaly in this regional pattern where an M2 metamorphic phase is attributed to localized D2 thrust stacking along the southern margin of the Culm Basin.
There is no extensive overprint of the regional metamorphic pattern by the contact aureoles surrounding the granite plutons of the region. However, there is a noticeable coincidence between the areas of regional epizone grade and the extent of the geophysically defined subsurface limit of the granite batholith (excluding the North Devon area). This link is attributed largely to the late-stage structural up-doming of the higher grade areas over the roof of the batholith.  相似文献   

涡流地震检波器的理论研究     

王宝昌  董连芝  董世学 《吉林大学学报(地球科学版)》1995,(4)

根据严格的数学推演给出涡流地震检波器电压的频率响应特性、阻尼因数、位相等的正确公式；定义表征其某些基本特征的物理量；讨论了文献［１］中某些严重错误，简介了我们研制的新型涡流地震检波器的某些性能。  相似文献   

疏勒河断裂中段VLF响应特点及地质解释     

莫撼  熊章强 《华东地质学院学报》1995,18(3):249-251

疏勒河断裂带中段为一隐伏基底断裂。由于规模较大，并且充填了低阻的构造角砾岩，因此对ＶＬＦ有很好的响应。本文分析了该构造的ＶＬＦ响应特点，指出在本区用ＶＬＦ方法寻找隐伏构造的有效性和局限性。  相似文献   

Very low-grade metamorphic study in the pre-Late Cretaceous terranes of New Caledonia (southwest Pacific Ocean)     

Sébastien  Potel 《Island Arc》2007,16(2):291-305

Abstract   Pre-Late Cretaceous terranes from the central part of New Caledonia have been metamorphosed under very low-grade conditions by two high-pressure/low-temperature events. The present study investigates the metamorphic patterns with phyllosilicate crystallinities, electron microprobe analyses and petrography. The first metamorphic event is of Late Jurassic age and is characterized by very low (anchizone) to low-grade (epizone) conditions with a decrease of the illite Kübler Index (KI) and the chlorite Árkai Index (ÁI) values from northeast to southwest. This trend is also confirmed by chlorite thermometry. In the south of the area, un-metamorphosed sediments (diagenetic KI values) are observed in the Senonian 'formation à charbons', post-dating the metamorphism in this region. The second metamorphism is an Eocene high-pressure event, which overprints the Late Jurassic metamorphism in the northern part of the studied area. In this zone, the pattern of KI and ÁI indicates another gradient with increasing metamorphic conditions from southwest to northeast. Temperatures calculated by chlorite thermometry also indicate an evolution from southwest to northeast with slight increase of temperature from 298 ± 8°C to 327 ± 16°C. In both metamorphic zones, the K-white mica b cell dimension calculated on micas analyzed at electron microprobe are in good agreement with high-pressure/low-temperature metamorphic conditions (b₀ > 9.04 Å). A combination of chlorite thermometry and K-white mica b cell dimension allows estimation of a minimum pressure of 1.3 GPa in the Eocene zone (in excellent agreement with the 1.5 GPa registered in the northern part of New Caledonia) and a minimum of 1.1 GPa in the Late Jurassic metamorphic part.  相似文献   

甚低频电磁法在某萤石矿勘查中的应用   总被引：6，自引：0，他引：6  

白大明  关继东  苏来柱 《物探与化探》2002,26(1):39-41

内蒙古海力敏萤石矿属热液脉型,萤石—石英矿受花岗岩体内NW向断裂破碎带控制。矿区开展了甚低频电磁法找矿勘查研究,在已知矿体上测得明显的甚低频电磁异常,证实了该方法对寻找此类萤石矿床的有效性。在不易识别开采的掩盖区,所测甚低频电磁异常显示控矿断裂带仍存在,极可能赋存萤石矿体。  相似文献