Multiresolution Analysis of Active Region Magnetic Structure and its Correlation with the Mount Wilson Classification and Flaring Activity     

J. Ireland  C. A. Young  R. T. J. McAteer  C. Whelan  R. J. Hewett  P. T. Gallagher 《Solar physics》2008,252(1):121-137

Two different multiresolution analyses are used to decompose the structure of active-region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found. These lines are used as a mask on a map of the magnetic field gradient to sample the local gradient between opposite polarity regions of given scale sizes. It is shown that the maximum, average, and standard deviation of the magnetic flux gradient for α,β,β γ, and β γ δ active-regions increase in the order listed, and that the order is maintained over all length scales. Since magnetic flux gradient is strongly linked to active-region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all length scales in the active-region, and not just those length scales at which the strongest flux gradients are found. Further, it is also shown that the average gradients in the field, and the average length-scale at which they occur, also increase in the same order. Finally, there are significant differences in the gradient distribution, between flaring and non-flaring active regions, which are maintained over all length scales. It is also shown that the average gradient content of active-regions that have large flares (GOES class “M” and above) is larger than that for active regions containing flares of all flare sizes; this difference is also maintained at all length scales. All of the reported results are independent of the multiresolution transform used. The implications for the Mt. Wilson classification of active-regions in relation to the multiresolution gradient content and flaring activity are discussed.  相似文献   

河西地区土地利用/覆盖变化驱动力研究   总被引：14，自引：7，他引：7  

张勃  张华 《干旱区地理》2004,27(2):234-238

河西地区的土地利用／覆盖格局2000多年来发生了很大的变化。参考大量的数据与资料分析了河西地区土地利用覆盖变化的驱动力,结果表明,自然机制与人为机制同时改变着该地区的土地利用／覆盖状况,自然机制的驱动是缓慢的,长期的,而人为机制的驱动,尤其到了近现代,则是剧烈的,集中的,人口变化是驱动土地利用／覆盖变化的非常活跃的因素。  相似文献   

西部干旱区生态景观格局动态分析   总被引：15，自引：9，他引：6  

马媛  师庆东  潘晓玲 《干旱区地理》2004,27(4):516-519

以1982～2000年NQAA气象卫星数据为基本信息源,在AIRC／INFO支持下,将遥感影像进行分区切割,按海拔进行分类,通过对景观优势度指数、斑块密度、边缘密度和分维数等指数的计算,对西部干旱区近20年以来的景观动态特征进行了全面分析,结果表明：各类景观类型所占比例差异较大,沙漠、戈壁无植被区景观类型在本区生态景观中优势度最大,占支配地位,绿洲作为斑块镶嵌于其上;近20年,平原地区的中覆盖度草地和高覆盖度草地在研究区所占的百分比呈明显下降趋势,而绿洲所占比例呈上升趋势,表明这两类植被有相互转换的关系;平原丘陵区的自然景观斑块分维数在增长,绿洲景观类型斑块的分维值在减小,斑块形状趋于规则化。西部干旱区气候变化及人类活动已成为本地区生态景观格局变化的重要因素。  相似文献   

东秦岭造山带"两阶段双带"区域成矿模式     

谢才富  熊成云  胡宁  李劲松 《地质科技情报》2004,23(2):77-81

东秦岭造山带总体上可划分为中元古代-古生代主要与裂谷、坳陷槽有关的海盆同生沉积成矿以及中生代与大规模陆内俯冲造山体制有关的后生热液成矿两大阶段,且中生代所形成的浅成和中深成两类热液矿床在横向上分带并呈相邻平行展布,成对共生,构成双成矿带,其形成机制是扬子地块及华北地块分别往秦岭发生陆内俯冲,使与挤压、转换挤压-变质变形、深成侵入-深源流体成矿系统有关的中深成热液型矿床形成于仰冲板片前缘的推覆-隆升带中;而使与伸展-高地热场(火山、浅成侵入)-地热流体成矿系统有关的浅成热液型矿床形成于推覆-隆升带后侧的同碰撞伸展带中.  相似文献   

区域旅游合作演化与动因的系统学分析--兼论"西安咸阳旅游合作"   总被引：32，自引：7，他引：25  

梁艺桦  杨新军  马晓龙 《地理与地理信息科学》2004,20(3):105-108

应用系统学自组织理论,对区域旅游合作演化与动因进行探讨。笔者认为,区域旅游合作是地方旅游子系统自组织过程中的必然选择,而目的性和创新性是促使各子系统之间进行区域旅游合作的动因。并以这一演化规律对“西安咸阳旅游合作”进行论证,以期为“区域旅游合作”利益主体——地方旅游部门政策的制定和实施提供依据。  相似文献   

苏锡常地区浅层地下水开采技术研究及环境效应分析     

王彩会  朱锦旗  陈杰 《地质灾害与环境保护》2004,15(1):42-45

通过在苏锡常地区选择典型地段进行浅层地下水开采试验工作,从浅层地下水水文地质条件(含水层展布、岩性、厚度、水质)综合分析其开发利用前景,提出了合理的浅层地下水开采方式及地下水的利用方向,对于保护深层水资源,防止地面沉降及土壤盐渍化有十分重要的意义。  相似文献   

秦岭岩群中斜长角闪岩的年代学及地质意义     

柏治安  时毓  刘希军  刘磊  赵增霞  黄倩雯 《地质论评》2019,65(Z1):41-42

正秦岭造山带是华北陆块和扬子陆块及其间的微陆块经历了多期拼合而形成的,具有复杂的构造演化史,前人已对其形成与演化过程进行了大量的研究工作,但在许多方面的研究仍未获得统一的认识(张国伟等,1988;张本仁等2002)。秦岭岩群是北秦岭造山带的主体,保存了复杂的变质变形记录,准确有效地获取和判断其基底岩石的形成和变质时代是探讨秦岭岩群乃至整个秦岭造山带形成  相似文献   

博格达地区中二叠统页岩层系古沉积环境     

王越  林会喜  张奎华  张关龙 《地质论评》2019,65(Z1):93-94

正博格达山西段在早-中二叠世尚未隆升,该地区在中二叠世后期发生大规模湖侵,准噶尔盆地与吐哈盆地水体相连通成为统一的沉积体系。准噶尔盆地南缘自下而上发育了芦草沟组与红雁池组,吐哈盆地西北缘发育了塔尔朗组,其中芦草沟组与塔尔朗组发育厚层的深灰色泥页岩、页岩及油页岩,夹有薄层的灰岩、白云岩,为研究区重要的烃源岩层系。目前,关于这套层系的层序地层特征研究较多,  相似文献   

Sedimentary processes,stratigraphic sequences and middens: the link between archaeology and geoheritage—a case study from the Quaternary of the Broome region,Western Australia     

P. Clifford 《Australian Journal of Earth Sciences》2019,66(6):955-972

The cliffed and active dune coastal region of Broome provides an excellent record of Pleistocene and Holocene stratigraphy of desert environments interfacing with the Indian Ocean. The Mesozoic Broome Sandstone is the basal stratigraphic unit in the area and is overlain by Pleistocene red desert quartz sand (Mowanjum Sand). Modern coastal processes of waves, wind and tide have resulted in distinctive sedimentary bodies (stratigraphic units) clearly linked to the sedimentary environment. The Mowanjum Sand, reworked by coastal winds, generates the landward-ingressing orange quartzose Churchill Sand, or reworked by waves and abraded to white sand with the addition of carbonate grains that form the beaches (Cable Beach Sand) and with eolian action, coastal dunes or inland-ingressing white dunes (Shoonta Hill Sand). These sedimentary bodies and stratigraphic units form a template with which to locate and interpret archaeological middens and Indigenous occupation over the past 5000?years in a context of coastal occupation, coastal stability, mean sea-level changes, climate changes, and availability of marine food and freshwater. Shell middens and stone artefacts form definitive layers or horizons in relation to the stratigraphy, in places in situ, and elsewhere reworked as sheets and plumes; understanding their inter-relationships has enabled the unravelling of the archaeological history and relating Indigenous occupation to biofacies and lithofacies. The array of sedimentary, biofacies and stratigraphic units are of national geoheritage significance in their own right. The addition of archaeological deposits as stratigraphic units provides a link between geoheritage and archaeology, where the archaeological materials are viewed as part of the complex stratigraphic story, part of the coastal history, and part of the geoheritage story.  相似文献   

三峡库区巫山金鸡岭滑坡成因机制与变形特征     

闫国强  殷跃平  黄波林  张枝华  代贞伟 《岩土力学》2019,40(Z1):329-340

三峡库区新城区迁建多采用就地后靠方式,工程扰动叠加强降雨往往诱发滑坡失稳。基于重庆巫山江东小区金鸡岭滑坡,对其影响因素和成因机制进行探讨。工程扰动不仅是传统认为的后缘加载、前缘削脚作用,更重要的是坡体表层土方堆填阻断了滑坡体地表水泄流通道,使地表水向地下水转化。强降雨作用下滑坡体内地下水位明显升高,导致金鸡岭滑坡2018年8月1日前后发生较大变形。采取降水井抽排地下水等应急处置后,滑坡变形明显趋缓,可见工程扰动导致的地下水升高是该滑坡诱发的关键因素。数值模拟表明,工程扰动后稳定系数明显降低,对应堆填区渗流场变化明显,渗流加剧,孔隙水压力、水力梯度、总水头上升,结合达西定律与有效应力原理可知渗透力增加,抗剪强度削弱,诱发滑坡变形。  相似文献