Characteristics and Altitudinal Distribution of Periglacial Decay Phenomena in the Massif of Rondane,Central Norway          下载免费PDF全文

Riwan Kerguillec 《Geografiska Annaler: Series A, Physical Geography》2015,97(2):299-315

The Norwegian massif of Rondane is part of the Scandes Mountains and is subject to polar, oceanic and continental influences. Because of its climatic context and its quartzitic structure, the massif has one of the thickest functional periglacial belts in Europe (1200 m). This belt is not fixed considering its translation in altitude since the end of the Little Ice Age. This mobility is continuing and involves periglacial decay dynamics which are revealed by numerous and various periglacial forms in the field. Because of their frequency in the massif and also their sensitivity to climate fluctuations, earth patches and small non‐sorted circles have a diagnostic value for current periglacial climate fluctuations. The major aim of this study is to propose several indicators of this periglacial decay and to highlight its consequences on periglacial belt mobility because these landforms enable the delimitation of a critical belt of decay in the massif.  相似文献   

高山冰川多时相多角度遥感信息提取方法   总被引：1，自引：0，他引：1  

都伟冰  李均力  包安明  王宝山  王双亭 《测绘学报》2015,44(1):59-66

提出一种多角度遥感影像的冰川信息提取方法。通过"全域—局部"的阈值分割方法获取短时期内不同时相的遥感影像的冰雪边界,结合地形信息和多时相遥感影像的太阳角度信息,联合消除山体阴影对冰川的遮挡,并以多期影像的最小冰雪边界作为最佳冰川边界。以托木尔峰西侧冰川为研究对象,采用2009—2010年4个时相的遥感影像提取冰川信息。结果表明多角度遥感提取的冰川边界效果好,能有效地排除积雪与山体阴影的干扰。  相似文献   

引发广西两次严重山洪地质灾害的暴雨过程分析   总被引：2，自引：0，他引：2  

刘国忠  黄嘉宏  曾小团  农孟松  黄海洪 《气象》2013,39(11):1402-1412

利用常规观测、卫星云图、雷达探测以及自动站雨量等资料,对2010年6月27—28日和2012年5月20—22日桂西北两次严重山洪地质灾害的气象条件进行了对比分析,结果表明：(1) 强降雨发生在桂西北暴雨区,最大过程雨量＞350 mm,过程最大中尺度雨团和致灾区最大中尺度雨团值分别＞100 mm·h-1和＞70 mm·h-1,集中降雨时段为02—06时。灾害开始于后半夜,发生在最大过程雨量和地质条件脆弱区,不同的地质状况对应不同的灾害;灾害性天气具有区域小、降雨时段集中、过程雨量大、强度强及引发灾害重等特征。(2) 暴雨发生在欧亚地区500 hPa呈两脊一槽型、200 hPa南亚高压脊线贯穿广西上空及季风云系活跃的背景下。高空为槽或低涡、地面为干线或锋面,属低涡暴雨型。(3) 高空要素变化为雨前降压升温、后降温。不稳定能量及层结、低层辐合、中低层涡旋、整层大气的上升运动、高温高湿及水汽强烈辐合是物理量特征。(4) 云图上对流云团生成、合并对强降雨有指示意义,暴雨发生在云团合并发展阶段;TBB值＜200 K可以作为强降雨的指标。低质心强雷达回波产生的列车效应或回波停滞和地形作用是造成强降雨的重要因素,低层辐合、高层辐散导致了强烈的上升运动,有利于强对流的发展与维持。  相似文献   

西天山海西中期花岗岩的地质特征及其构造环境   总被引：1，自引：0，他引：1  

李伍平  姜常义  吴文奎  谢广成 《地球科学与环境学报》1995,(4)

海西中期花岗岩是西天山加里东褶皱带内规模最大的一次岩浆活动。本文从岩石学、矿物学、岩石化学和地球化学等方面对该期花岗岩的成因类型、岩浆起源和形成的构造环境进行了探讨，认为海西中期花岗岩以Ｉ型为主，Ｓ型次之，在空间上成对分布，花岗岩浆起源于地壳；海西中期花岗岩形成于活动大陆边缘岛孤环境．  相似文献   

Evaluation of spatial variability in snow water equivalent for a high mountain catchment     

S. P. Anderton  S. M. White  B. Alvera 《水文研究》2004,18(3):435-453

Multivariate statistical analysis was used to explore relationships between catchment topography and spatial variability in snow accumulation and melt processes in a small headwater catchment in the Spanish Pyrenees. Manual surveys of snow depth and density provided information on the spatial distribution of snow water equivalent (SWE) and its depletion over the course of the 1997 and 1998 melt seasons. A number of indices expressing the topographic control on snow processes were extracted from a detailed digital elevation model of the catchment. Bivariate screening was used to assess the relative importance of these topographic indices in controlling snow accumulation at the start of the melt season, average melt rates and the timing of snow disappearance. This suggested that topographic controls on the redistribution of snow by wind are the most important influence on snow distribution at the start of the melt season. Furthermore, it appeared that spatial patterns of snow disappearance were largely determined by the distribution of snow water equivalent (SWE) at the start of the melt season, rather than by spatial variability in melt rates during the melt season. Binary regression tree models relating snow depth and disappearance date to terrain indices were then constructed. These explained 70–80% of the variance in the observed data. As well as providing insights into the influence of topography on snow processes, it is suggested that the techniques presented herein could be used in the parameterization of distributed snowmelt models, or in the design of efficient stratified snow surveys. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Development and Conservation of Glacier Tourist Resources —— A Case Study of Bogda Glacier Park   总被引：3，自引：0，他引：3  

LIU Xuling YANG Zhaoping XIE Ting 《中国地理科学(英文版)》2006,16(4):365-370

1 Introduction As a special kind of tourism, glacier tourism is popular to tourists all over the world owing to its meeting tourists’ needs for seeking after freshness, difference, surprise and risk. Differing from conventional tourism, glacier tour- ism has its special characters while there is little literature on it. It is of great significance to study its characters and seek after the harmonious development in exploitation and protection of glacier tourism resources. Glacier tourism refe…  相似文献   

北秦岭官坡地区柯石英榴辉岩变质作用的P－T－t轨迹     

Zhao Donglin 《地球科学与环境学报》1997,(2)

根据矿物包裹和替代关系以及共生组合规律，北秦岭官坡地区柯石英榴辉岩的变质作用演化可划分为５个阶段，即前榴辉岩相的绿帘角闪岩相、榴辉岩相、后榴辉岩相的角闪岩相、绿帘角闪岩相和绿片岩相。Ｓｍ－Ｎｄ同位素定年显示，北秦岭柯石英榴辉岩于４００±１６Ｍａ沿朱夏断裂被推覆上升，Ｐ－Ｔ－ｔ轨迹的地球动力学成因可能与扬子和华北陆块间的俯冲－碰撞作用有关。  相似文献   

1988年1月云南威信墨黑山地灾害     

吴其伟  李德基  朱平一  冯水志 《山地学报》1988,(3)

这次山地灾害由岩崩、滑坡和泥石流三类灾害组成。在我国西南,隆冬少雨季节出现这类山地灾害是罕见的。这次山地灾害正是发生于1988年1月,具有一定的特殊性。究其原因是,当地某些较为特殊的自然条件和采煤不当,促使山体岩崩崩积物逐年加载,进而引起滑坡、泥石流的发生。灾害造成的直接经济损失合人民币58.6万元。对此种山地灾害宜采取以避害为主的防治措施。  相似文献   

AN　ANALYSIS　OF　WATER　RESOURCE　CHARACTERISTICS　OF　THE　RIVERS　IN　THE　NORTHERN　SLOPE　OF　THE　KUNLUN　MOUNTAINS     

许有鹏  高蕴珏 《中国地理科学(英文版)》1995,5(4):365-373

ＡＮＡＮＡＬＹＳＩＳＯＦＷＡＴＥＲＲＥＳＯＵＲＣＥＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＴＨＥＲＩＶＥＲＳＩＮＴＨＥＮＯＲＴＨＥＲＮＳＬＯＰＥＯＦＴＨＥＫＵＮＬＵＮＭＯＵＮＴＡＩＮＳＸｕＹｏｕｐｅｎｇ（许有鹏）；ＧａｏＹｕｎｊｕｅ（高蕴珏）（Ｄｅｐａｒｔ...  相似文献   

TOPOGRAPHIC SHADING AND GEOGRAPHICAL PATTERNS OF DIRECT SOLAR RADIATION IN MOUNTAINOUS REGIONS*     

Dale J. Stevens  Alan H. Grey 《The Professional geographer》1986,38(4):383-390

Topographic shading curtails the period and complicates the geographic patterns of insolation in mountainous areas. Maps derived from oblique aerial photographs of shadow lines cast by the irregular, mountainous east horizon in Provo, Utah are used as a case study to illustrate an alternative to existing techniques of solar radiation data collection. For study areas of several hundred square kilometers, this method may be superior in resolution and at the same time more error free and economically feasible than other methods. Measurement of solar inputs received at sample stations scattered through the mapped area show that the phenomenon of topographically delayed sunrise has a distinct effect on daily totals of radiation in the manner suggested by the maps.  相似文献