磁暴时磁场变化率与地电场相关性研究   总被引：5，自引：4，他引：1  

张素琴  杨冬梅 《地震地磁观测与研究》2010,31(3):7-12

对2003年10月29日、10月30日两个典型大磁暴进行了分析,研究了磁暴期间磁场变化率与地电场的关系,以及磁暴期间磁暴、磁场变化率及地电场的周期成分。结果表明,磁暴期间H分量变化率与地电场东向分量观测数据显著相关,并且周期成分相同。  相似文献   

JCZ-1T超宽频带地震计LP垂直通道记录的固体潮特征     

曾宪军  孙宏博  张娟  陈俊 《地震地磁观测与研究》2010,31(4):108-114

JCZ-1T超宽频带地震计具有全频带覆盖特性,其低频端输出延伸到固体潮汐,利用地震计LP通道的垂直分向观测数据,经过处理获得有关的固体潮资料,通过对记录信号的频谱分析对其有了初步的认知。JCZ-1T超宽频地震计LP加速度垂直通道记录的观测信号以固体潮汐信息为主,用该仪器观测可以获取与地震相关的综合观测数据,分析JCZ-1T记录波形叠加的的固体潮信息有着重要的实际意义,通过对资料处理运用,可以与传统前兆仪器结合观测,拓展其研究应用领域,更好的服务于地震科学研究。  相似文献   

龙岩地震台GM4型磁通门磁力仪典型干扰分析     

杨佩琴  刘其寿  王绍然  黄鹤凌  郑永通 《华北地震科学》2010,28(4):60-63

GM4型磁通门磁力仪是"十五"项目中地磁学科主要仪器。龙岩台GM4型磁通门磁力仪主要受到来自铁磁性物质和电磁类型的干扰。由已知干扰类型,对记录曲线典型畸变形态进行对比、分析、总结,可以更好分辨干扰,进行恰当、合理、准确地预处理,保证数据的连续、可靠、精确。  相似文献   

转型期中国城镇居民住房类型分化及其影响因素——基于CGSS (2005) 的分析   总被引：6，自引：1，他引：5  

刘望保  闫小培  曹小曙 《地理学报》2010,65(8):949-960

转型时期我国城镇居民主要通过市场竞争机制和科层分配体制来获取个人住房,获取稀缺的住房资源的途径和机会的差异在一定程度上反映了住房不平等和社会分化。处于体制转型时期的中国城镇,制度、市场和家庭因素等多重因素相互交织,共同影响中国城镇居民住房选择。以覆盖全国88 个城镇的《中国综合社会调查(CGSS)》(2005 年城镇部分) 调查资料为基础,本文分析了转型背景下中国城镇居民住房类型分化及其影响因素,研究发现：改革 开放30 多年以来,中国城镇的住房自有率大幅度提高,其主要原因从1998 年前的公房房改政策向1998 年后住房市场化政策转变。家庭生命周期、家庭收入、户籍、单位性质、职业等变 量显著影响住房选择,体现市场与制度对住房资源分配的双重影响。经济发达地区由于住房资源紧缺、住房价格高,居民住房承受能力差异较大,工作单位性质、户籍和家庭生命周期变量对住房选择的影响更显著。随着住房市场化进一步发展和住房制度改革的逐步深入,地方政府应逐步放宽社会住房的享受标准,尤其是户籍限制条件;开发商应更关注社会经济快 速转型背景下的家庭结构变化及其对居住偏好的影响。  相似文献   

Coastal dune rock development and Holocene climate changes in South China     

WANG Wei  WU Zheng 《地理学报》2010,20(3):469-480

Coastal dune rocks in China are eolian sands cemented by calcium carbonate under subaerial conditions, widely distributing on the tropical and subtropical coasts of South China. Particular temperature and precipitation as well as local wave and landform conditions are required for the formation of the dune rocks. A correspondence was found between Holocene environmental changes and coastal dune rock development by comparing the features of the sea-level and climate changes in the Holocene period with the ages, scales, and cementation of the dune rocks on the South China coasts. The findings provide well grounded explanation for some problems unresolved in the past researches on the coastal dune rock in South China: (1) There were no dune rocks with ages older than 6000 years in South China because the dune rocks formed before 6000 a BP were covered by the sea water that rose in the later period; (2) the dune rocks with ages of around 3000 a BP were widely found in South China today because the coastal dunes were cumulated on a large scale at that time as a result of temperature falling after the end of Megathermal; (3) Medieval Warm Period was the main period for the eolian dunes to be cemented into the coastal dune rocks in South China; (4) lack of dune rocks of younger than 1000 a BP was accounted for by that the climate conditions in recent one thousand years were not suitable for the cementation.  相似文献   

Forest land use change at Trans-Boundary Laos-China Biodiversity Conservation Area     

HEMMAVANH Chanhda  YE Yanmei  YOSHIDA A 《地理学报》2010,20(6):889-898

This paper analyzed forest land use change in Trans-Boundary Laos–China Biodiversity Conservation Area which is called Namha National Biodiversity Conservation Areas (Namha NBCAs), with 1992 and 2002 TM (ETM). Based on GIS and statistical methods, the intensity, state index of land use change and transfer matrix were used to study spatio- temporal land use change in the region. The results showed that the area of forest land decreased greatly, also the area of bamboo and grassland decreased. The other way round, the area of unstocked forest, slash and burn and rice paddy land increased. As a whole, the intensity of forest land change was higher, but others were lower. From the transfer matrix, most of the forest land changed into unstocked forest and urban area, some to slash and burn. The grassland and bamboo were mainly transferred to forest and unstocked forest. The unstocked forest land mostly came from forest land and grassland. It was showed there were three main causes of the land use change namely: opium poppy cultivation, rubber plantation and also ecotourism activities and finally some policies were developed in order to address the land use change in the study areas.  相似文献   

Variation and abrupt change of climate in Ili River Basin, Xinjiang     

SUN Huilan  CHEN Yaning  LI Weihong  LI Feng  CHEN Yapeng  HAO Xingming  YANG Yuhui 《地理学报》2010,20(5):652-666

In this paper, the monthly precipitation and temperature data collected at 7 stations in the Ili River Basin from 1961 to 2007 were analyzed by means of simple regression analysis, running mean, db6 wavelet function and Mann-Kendall test. This study revealed the characteristics of climate change and abrupt change points of precipitation and temperature during different time scales in the Ili River Basin within the past 50 years. The results showed that the precipitation increased from the mid-1980s until 2000 and has continued to increase at a smaller magnitude since 2000. Over the studied period, the precipitation increased significantly during the summer and winter months. The temperature increased greatly in the late 1980s, and has continued to show an increasing trend from the year 2000 to present. The temperature increases were most significant during the summer, autumn and winter months. In terms of different geographies, the temperature increase was significant during the winter in the plains and hilly regions; the increase was also significant during autumn in the intermontane basins. The climate change trends in the Ili River Basin were consistent with the changing trends of the North Atlantic Oscillation and the plateau monsoon.  相似文献   

Glacial change in the vicinity of Mt. Qomolangma (Everest), central high Himalayas since 1976     

NIE Yong  ZHANG Yili  LIU Linshan  ZHANG Jiping 《地理学报》2010,20(5):667-686

Glaciers are one of the most important land covers in alpine regions and especially sensitive to global climate change. Remote sensing has proved to be the best method of investigating the extent of glacial variations in remote mountainous areas. Using Landsat thematic mapping (TM) and multi-spectral-scanner (MSS) images from Mt. Qomolangma (Everest) National Nature Preserve (QNNP), central high Himalayas for 1976, 1988 and 2006, we derived glacial extent for these three periods. A combination of object-oriented image interpretation methods, expert knowledge rules and field surveys were employed. Results showed that (1) the glacial area in 2006 was 2710.17 ± 0.011 km2 (about 7.41% of the whole study area), and located mainly to the south and between 4700 m to 6800 m above sea level; (2) from 1976 to 2006, glaciers reduced by 501.91 ± 0.035 km2 and glacial lakes expanded by 36.88 ± 0.035 km2; the rate of glacier retreat was higher in sub-basins on the southern slopes (16.79%) of the Himalayas than on the northern slopes (14.40%); most glaciers retreated, and mainly occurred at an elevation of 4700–6400 m, and the estimated upper limit of the retreat zone is between 6600 m and 6700 m; (3) increase in temperature and decrease in precipitation over the study period are the key factors driving retreat.  相似文献   

ESTABLISHING LICHENOMETRIC AGES FOR NINETEENTH- AND TWENTIETH-CENTURY GLACIER FLUCTUATIONS ON SOUTH GEORGIA (SOUTH ATLANTIC)     

BY STEPHEN J. ROBERTS  DOMINIC A. HODGSON  SAMANTHA SHELLEY  JESSICA ROYLES  HUW J. GRIFFITHS  TARA J. DEEN  MICHAEL A.S. THORNE 《Geografiska Annaler: Series A, Physical Geography》2010,92(1):125-139

Glaciers in small mountain cirques on South Georgia respond rapidly and sensitively to changes in South Atlantic climate. The timing and rate of their deglaciation can be used to examine the impact that nineteenth- and twentieth-century climate change has had on the glacial dynamics and terrestrial ecosystems of South Georgia. As part of a reconnaissance study in Prince Olav Harbour (POH), South Georgia, we measured the size of lichens ( Rhizocarpon Ram. em Th. Fr. subgenus. Rhizocarpon group) on ice-free moraine ridges around two small mountain cirques. Our aims were twofold: first, to provide age estimates for lichen colonization, and hence, deglaciation of the moraine ridges, and second, to examine the potential of applying lichenometry more widely to provide deglacial age constraints on South Georgia. In the absence of lichen age-size (dating) curves for South Georgia, we use long-term Rhizocarpon lichen growth-rates from recent studies on sub-Antarctic Islands and the western Antarctic Peninsula to calculate likely age estimates. These data suggest ice retreat from the two outermost moraines occurred between the end of the 'Little Ice Age' (post c. 1870) and the early twentieth century on South Georgia. Lichen colonization of the innermost moraines is probably related to glacier retreat during the second half of the twentieth century, which has been linked to a well-defined warming trend since c. 1950. Patterns of possible nineteenth- and twentieth-century glacial retreat identified in POH need to be tested further by establishing species- and site-specific lichen age-size (dating) curves for South Georgia, and by applying lichenometry to other mountain cirques across South Georgia.  相似文献   

阿克苏河流域气候变化对潜在蒸散量影响分析   总被引：13，自引：1，他引：12  

张守红  刘苏峡  莫兴国  舒畅  孙杨  张春 《地理学报》2010,65(11):1363-1370

蒸散发是水文过程的关键环节,研究气候因子对潜在蒸散发的影响,有助于深入认识水文过程对气候变化的响应。本文基于阿克苏河流域1960-2007 年逐日气象资料和Penman-Monteith公式,估算并分析参考作物蒸散量(RET) 时空变化特征,并用多元回归方法定量区分气候因子变化对RET 变化的贡献率。研究发现流域RET 空间差异明显,东部平原区平均年RET 为1100mm左右,是西部山区的近2 倍;东南部绿洲区的RET显著减少,而西部变化复杂。RET变化趋势的季节差异也很显著,以夏季变幅最大,是年变化的主要贡献者。高海拔地区相对湿度对RET变化影响最大,其它区域的风速变化对RET变化的贡献率最高。库车和乌恰站的风速变化对RET变化的贡献率大于50%,是RET变化的主导因素。  相似文献