Chemical Weathering in the Batura Glacier Basin, Karakoram Mountains     

Wang Ninglian  Yao Tandong  Fu Zongtang  Yang Zhiqiang WT  ”BX 《地学前缘》2000,(Z1)

CHEMICAL WEATHERING IN THE BATURA GLACIER BASIN, KARAKORAM MOUNTAINStheChineseNationalBasicResearchProgramme(GrantG 19980 4 0 80 0 )andChineseNationalScienceFoundation (NSFgrant 4 980 10 0 4 )  相似文献   

The Verification and Significance of Three Approaches to Longitudinal Stresses in High–resolution Models of Glacier Flow     

Alun Hubbard 《Geografiska Annaler: Series A, Physical Geography》2000,82(4):471-487

With the purpose of improving the ice physics underpinning time–dependent glacier flowline models, three independent approaches for solving longitudinal stresses in glaciers are discussed and verified by application to Haut Glacier d'Arolla. To highlight any shortcomings, the reduced and much utilised driving stress approximation is also applied and compared. Modelled velocity patterns using the three full stress schemes exhibit consistency with one another and good coincidence with observed velocities for the 1991 summer melt season. Furthermore, these stress patterns indicate that longitudinal stresses are significant and of a similar order of magnitude as the basal shear stress components. However, the driving stress approximation yields erratic fluctuations in the stress and velocity fields which are neither realistic in terms of mass continuity nor agree with observations. Basal decoupling experiments indicate a complex relationship between basal velocity and englacial stresses with considerable dampening of any basal perturbation occurring as it is dissipated towards the surface and transferred throughout the ice mass. The driving stress approximation fails to account at all for any such coupling. Experiments to identify the length scale over which longitudinal effects operate indicate that they are significant even up to 10 ice thicknesses. The implication here is that longitudinal stresses play a significant role in determining glacier dynamics on length scales up to at least 2 km and that the predictive power of models of glacier flow based purely on the driving stress approximation is therefore subject to significant limitations. Inclusion of longitudinal stresses overcomes one of the main limitations imposed on such models and, given the potential ease of incorporation of the schemes described here, this deficiency may readily be resolved.  相似文献   

一条Rodinia山脉——震旦纪的喜马拉雅山     

林晓辉 《华北地质》2000,(4)

笔者首次将海拔高度的概念及现代冰川理论 ,并结合古地磁资料 ,提出罗圈冰期时古天山 -秦岭山脉是一条大约位于赤道 -北回归线之间、由众多高山组成的 ,且许多山峰至少在 4 0 0 0m以上 ,已形成冰川、或许局部地区存在冰原的山脉 ,总的地理特征类似于今天的喜马拉雅山脉。而华北地块和库鲁克塔格地块是高原或平原 ,此二地块的南边是海域。古秦岭的南坡是现代秦岭的北坡。冰川融化时冰水携带的冰碛物向南流入海 ,所以华北地块上无冰碛物存在大地构造上 ,晋宁期以前 ,上述各地块相互独立。震旦纪时它们开始发生作用 ,秦岭地块和阿克苏—乌什地块分别向华北地块与库鲁克塔格地块汇聚 ,引起后者上升 ,逐渐发展成为山脉。至震旦纪末期 ,山脉上升到 4 0 0 0m以上 ,形成冰川。此后 ,山脉被剥蚀夷平 ,至寒武纪初 ,华北、库鲁克塔格两地块又降到海平面之下接受沉积 ,该山脉消亡。由此我们恢复了新元古代超大陆一条造山带 ,并推测新元古宙末期华北、华南、塔里木三大地块曾经汇聚在一起  相似文献   

叶尔羌河冰川阻塞性洪水发生的气象因素     

刘皑国 《沙漠与绿洲气象(新疆气象)》2005,28(2):13-15

2002年8月12日，叶尔羌河再次发生因高原冰川阻塞形成的洪水。本文对叶尔羌河历次高原冰川阻塞性洪水的成因以及与气象的关系做了较详尽的分析，并提出了从气象角度预报该类型洪水的方法和利用卫星遥感技术对冰川阻塞湖进行监测的建议，期望对叶尔羌河今后的防洪工作有一些指导意义。  相似文献   

Basal sediment evacuation by subglacial meltwater: suspended sediment transport from Haut Glacier d'Arolla,Switzerland     

Darrel A. Swift  Peter W. Nienow  Trevor B. Hoey 《地球表面变化过程与地形》2005,30(7):867-883

Proglacial suspended sediment transport was monitored at Haut Glacier d'Arolla, Switzerland, during the 1998 melt season to investigate the mechanisms of basal sediment evacuation by subglacial meltwater. Sub‐seasonal changes in relationships between suspended sediment transport and discharge demonstrate that the structure and hydraulics of the subglacial drainage system critically influenced how basal sediment was accessed and entrained. Under hydraulically inefficient subglacial drainage at the start of the melt season, sediment availability was generally high but sediment transport increased relatively slowly with discharge. Later in the melt season, sediment transport increased more rapidly with discharge as subglacial meltwater became confined to a spatially limited network of channels following removal of the seasonal snowpack from the ablation area. Flow capacity is inferred to have increased more rapidly with discharge within subglacial channels because rapid changes in discharge during highly peaked diurnal runoff cycles are likely to have been accommodated largely by changes in flow velocity. Basal sediment availability declined during channelization but increased throughout the remainder of the monitored period, resulting in very efficient basal sediment evacuation over the peak of the melt season. Increased basal sediment availability during the summer appears to have been linked to high diurnal water pressure variation within subglacial channels inferred from the strong increase in flow velocity with discharge. Basal sediment availability therefore appears likely to have been increased by (1) enhanced local ice‐bed separation leading to extra‐channel flow excursions and[sol ]or (2) the deformation of basal sediment towards low‐pressure channels due to a strong diurnally reversing hydraulic gradient between channels and areas of hydraulically less‐efficient drainage. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Analyzing ice dynamics using Sentinel-1 data at the Solheimajoküll Glacier,Iceland     

Diego Gómez  Pablo Salvador  Julia Sanz  Mikhail Urbazaev  José Luis Casanova 《地理信息系统科学与遥感》2020,57(6):813-829

ABSTRACT

The climate in southern Iceland has warmed over the last 70 years, resulting in accelerated glacier dynamics at the Solheimajoküll glacier. In this study, we compare glacier terminus locations from 1973 to 2018, to changes in climate across the study area, and we derive ice-surface velocities (2015–2018) from satellite remote-sensing imagery (Sentinel-1) using the offset-tracking method. There have been two regional temperature trends in the study period: cooling (1973–1979) and warming (1980–2018). Our results indicate a time lag of about 20 years between the onset of glacier retreat (?53 m/year since 2000) and the inception of the warming period. Seasonally, the velocity time series suggest acceleration during the summer melt season since 2016, whereas glacier velocities during accumulation months were constant. The highest velocities were observed at high elevations where the ice-surface slope is the steepest. We tested several scenarios to assess the hydrological time response to glacier accelerations, with the highest correlations being found between one and 30 days after the velocity estimates. Monthly correlation analyses indicated inter-annual and intra-annual variability in the glacier dynamics. Additionally, we investigate the linkage between glacier velocities and meltwater outflow parameters as they provide useful information about internal processes in the glacier. Velocity estimates positively correlate with water level and negatively correlate with water conductivity between April and August. There is also a disruption in the correlation trend between water conductivity and ice velocity in June, potentially due to a seasonal release of geothermal water.  相似文献   

基于地理信息系统的太阳直接辐射与冰川物质平衡的关系   总被引：4，自引：1，他引：3  

丁永建 《冰川冻土》1998,20(2):157-162

基于冰川微地形对冰川物质平衡重要影响的认识,在考虑朝向、坡度、地形遮蔽等因素的条件下,以地理信息系统为手段,对乌鲁木齐河源１号冰川冰面太阳可能直接辐射进行了理论计算．在此基础上,建立了计算冰面任意一点物质平衡的Ｂ＝ｆ（Ｔ,Ｒ）（气温－辐射）模型．比较了该模型与Ｂ＝ｆ（Ｔ）（气温）模型、Ｂ＝ｆ（Ｐ,Ｔ）（降水－气温）模型及Ｂ＝ｆ（Ｑ）（能量平衡）模型之间的优缺点,表明该模型具有物理意义明确、计算精度较高、参数易于获得等优点,从而为计算冰川物质平衡提供了新的途径．  相似文献   

黄土堆积与冰期事件     

赵诚  王世梅 《地球科学与环境学报》2000,22(4)

黄土高原早期环境 ,应该同其周边环境大体相似 ,也存在冰期问题 :三套“砂质黄土”是冰期遗物的唯一表象 ,这是因为冰体夹在黄土层中间 ,基本丧失了冰川形成条件 ,故虽有冰期而无冰川 ,自然也就没有山岳冰川所形成的各类遗物 ,当然也包括冰川地貌的形踪  相似文献   

Analysis of Difference Between Direct and Geodetic Mass Balance Measurements at South Cascade Glacier, Washington   总被引：2，自引：0，他引：2  

Robert M. Krimmel 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):653-658

Net mass balance has been measured since 1958 at South Cascade Glacier using the 'direct method,' e.g. area averages of snow gain and firn and ice loss at stakes. Analysis of cartographic vertical photography has allowed measurement of mass balance using the 'geodetic method' in 1970, 1975, 1977, 1979–80, and 1985–97. Water equivalent change as measured by these nearly independent methods should give similar results. During 1970–97, the direct method shows a cumulative balance of about −15 m, and the geodetic method shows a cumulative balance of about −22 m. The deviation between the two methods is fairly consistent, suggesting no gross errors in either, but rather a cumulative systematic error. It is suspected that the cumulative error is in the direct method because the geodetic method is based on a non-changing reference, the bedrock control, whereas the direct method is measured with reference to only the previous year's summer surface. Possible sources of mass loss that are missing from the direct method are basal melt, internal melt, and ablation on crevasse walls. Possible systematic measurement errors include under-estimation of the density of lost material, sinking stakes, or poorly represented areas.  相似文献   

综合RS与GIS方法提取青藏高原冲川变化信息：以布喀塔格峰为例   总被引：33，自引：0，他引：33  

李震  孙文新  曾群柱 《地理学报》1999,54(3):263-268

冰川变化的常规观测方法在高原的大部分地区无法实施。遥感与地理信息系统技术的发展为研究冲川变化提供了有效的手段,本文以位于昆仑山脉中段的布喀塔格山峰冰川为例,利用１９７３年至１９９４年的ＲＢＶ,ＭＳＳ和ＴＭ遥感资料为信息源,综合目视判读与统计分析方法提取冰川界限,形成冰川边界图,并规一化坐标系统,以ＧＩＳ为工具分析该冲川群的变化情况,计算冲川进退变化速率。  相似文献