remote sensing estimates of glacier mass balances in the himachal pradesh western himalaya india abstract although they correspond to an important fraction of the total area of mountain glaciers 33 000 km2 out of 546 000 km2 himalayan glaciers and their mass balance are poorly sampled for example between 1977 and 1999 the average area surveyed each year on the field was 6 8 km2 only no direct mass balance measurement is available after 1999 to contribute to fill this gap we use remote sensing data to monitor glacier elevation changes and mass balances in the spiti lahaul region 32 2 n 77 6 e himachal pradesh western himalaya india our measurements are obtained by comparing a 2004 digital elevation model dem to the 2000 srtm shuttle radar topographic mission topography the 2004 dem is derived from two spot5 satellite optical images without any ground control points this is achieved thanks to the good on board geolocation of spot5 scenes and using srtm elevations as a reference on the ice free zones before comparison on glaciers the two dems are analyzed on the stable areas surrounding the glaciers where no elevation change is expected two different biases are detected a long wavelength bias affects the spot5 dem and is correlated to an anomaly in the roll of the spot5 satellite a bias is also observed as a function of altitude and is attributed to the srtm dataset both biases are modeled and removed to permit unbiased comparison of the two dem on the 915 km2 ice covered area digitized from an aster image on most glaciers a clear thinning is measured at low elevations even on debris covered tongues between 1999 and 2004 we obtain an overall specific mass balance of 0 7 to 0 85 m a water equivalent depending on the density we use for the lost or gained material in the accumulation zone this rate of ice loss is twice higher than the long term 1977 to 1999 mass balance record for himalaya indicating an increase in the pace of glacier wastage to assess whether these ice losses are size dependant all glaciers were classified into three samples according to their areal extent all three samples show ice loss the loss being higher for glaciers larger than 30 km2 in the case of the benchmark chhota shigri glacier a good agreement is found between our satellite observations and the mass balances measured on the field during hydrological years 2002 2003 and 2003 2004 future studies using a similar methodology could determine whether similar ice losses have occurred in other parts of the himalaya and may allow evaluation of the contribution of this mountain range to ongoing sea level rise

understanding the interrelationships among mass balance meteorology discharge and surface velocity on chhota shigri glacier over 2002 2019 using in situ measurements

the influence of debris cover and glacial lakes on the recession of glaciers in sikkim himalaya india we investigated area changes in glaciers covering an area of similar to 200 km 2 in the tista basin sikkim eastern indian himalaya between similar to 1990 and 2010 using landsat thematic mapper tm and indian remote sensing satellite irs images and related the changes to debris cover supraglacial lakes and moraine dam lakes the glaciers lost an area of 3 3 0 8 between 1989 90 and 2010 more detailed analysis revealed an area loss of 2 00 0 82 2 56 0 61 and 2 28 2 01 km 2 for the periods 1989 97 1997 2004 05 and 2004 2009 10 respectively this indicates an accelerated retreat of glaciers after 1997 on further analysis we observed 1 the formation and expansion of supraglacial lakes on many debris covered glaciers and 2 the merging of these lakes over time leading to the development of large moraine dam lakes we also observed that debris covered glaciers with lakes lose a greater area than debris covered glaciers without lakes and debris free glaciers the climatic data for 24 years 1987 2011 measured at the gangtok meteorological station 1812 m a s l showed that the region experienced a 1 0 degrees c rise in the summer minimum temperature and a 2 0 degrees c rise in the winter minimum temperature indicating hotter summers and warmer winters there was no significant trend in the total annual precipitation we find that glacier retreat is caused mainly by a temperature increase and that debris covered glaciers can retreat at a faster rate than debris free glaciers if associated with lakes

remotely sensed debris thickness mapping of bara shigri glacier indian himalaya despite the important role of supraglacial debris in ablation knowledge of debris thickness on himalayan glaciers is sparse a recently developed method based on reanalysis data and thermal band satellite imagery has proved to be potentially suitable for debris thickness estimation without the need for detailed field data in this study we further develop the method and discuss possibilities and limitations arising from its application to a glacier in the himalaya with scarce in situ data surface temperature patterns are consistent for 13 scenes of advanced spaceborne thermal emission and reflection radiometer aster and landsat 7 imagery and correlate well with incoming shortwave radiation and air temperature we use an energy balance approach to subtract these radiation or air temperature effects in order to estimate debris thickness patterns as a function of surface temperature both incoming shortwave and longwave radiation are estimated with reasonable accuracy when applying parameterizations and reanalysis data however the model likely underestimates debris thickness probably due to incorrect representation of vertical debris temperature profiles the rate of heat storage and turbulent sensible heat flux moreover the uncertainty of the result was found to increase significantly with thicker debris a promising result since ablation is enhanced by thin debris of 1 2 cm

on the accuracy of glacier outlines derived from remote sensing data deriving glacier outlines from satellite data has become increasingly popular in the past decade in particular when glacier outlines are used as a base for change assessment it is important to know how accurate they are calculating the accuracy correctly is challenging as appropriate reference data e g from higher resolution sensors are seldom available moreover after the required manual correction of the raw outlines e g for debris cover such a comparison would only reveal the accuracy of the analyst rather than of the algorithm applied here we compare outlines for clean and debris covered glaciers as derived from single and multiple digitizing by different or the same analysts on very high 1 m and medium resolution 30 m remote sensing data against each other and to glacier outlines derived from automated classification of landsat thematic mapper data results show a high variability in the interpretation of debris covered glacier parts largely independent of the spatial resolution area differences were up to 30 and an overall good agreement for clean ice with sufficient contrast to the surrounding terrain differences 5 the differences of the automatically derived outlines from a reference value are as small as the standard deviation of the manual digitizations from several analysts based on these results we conclude that automated mapping of clean ice is preferable to manual digitization and recommend using the latter method only for required corrections of incorrectly mapped glacier parts e g debris cover shadow

climatic effects and bedrock control on rapid fluctuations of chhota shigri glacier northwest himalaya india active tectonism in the himalaya and the long fault lineament controlling the east west river valleys play an important role in melt at the snouts of glaciers or their fluctuations during the year lower glacier limits are controlled by high winds from the indian plains flowing along the valleys fluctuations of the chhota shigri glacier depend on temperature variations at the junction with the chandra river valley and in the unconsolidated morainic debris below the glacier ice high flow rates in the ablation zone indicate that basal sliding is the main movement mechanism melt takes place mainly from advection and this process of melting during the summer season occurs both day and night

challenges and recommendations in mapping of glacier parameters from space results of the 2008 global land ice measurements from space glims workshop boulder colorado usa on 16 18 june 2008 the us national snow and ice data center held a glims workshop in boulder co usa focusing on formulating procedures and best practices for operational glacier mapping using satellite imagery despite the progress made in recent years there still remain many cases where automatic delineation of glacier boundaries in satellite imagery is difficult error prone or time consuming this workshop identified six themes for consideration by focus groups 1 mapping clean ice and lakes 2 mapping ice divides 3 mapping debris covered glaciers 4 assessing changes in glacier area and elevation through comparisons with older data 5 digital elevation model dem generation from satellite stereo pairs and 6 accuracy and error analysis talks presented examples and work in progress for each of these topics and focus groups worked on compiling a summary of available algorithms and procedures to address and avoid identified hurdles special emphasis was given to establishing standard protocols for glacier delineation and analysis creating illustrated tutorials and providing source code for available methods this paper summarizes the major results of the 2008 glims workshop with an emphasis on definitions methods and recommendations for satellite data processing while the list of proposed methods and recommendations is not comprehensive and is still a work in progress our goal here is to provide a starting point for the glims regional centers as well as for the wider glaciological community in terms of documentation on possible pitfalls along with potential solutions

from balance to imbalance a shift in the dynamic behaviour of chhota shigri glacier western himalaya india mass balance and dynamic behaviour of chhota shigri glacier have been investigated between 2002 and 2010 and compared to data collected in 1987 1989 during the period 2002 2010 the glacier experienced a negative glacier wide mass balance of 0 67 0 40 m a w e between 2003 and 2010 elevation and ice flow velocities are slowly decreasing in the ablation area leading to a 24 to 37 reduction in ice fluxes an expected response of the glacier dynamics to its recent negative mass balances the reduced ice fluxes still remain far larger than the balance fluxes calculated from the year 2002 to 2010 average surface mass balances therefore further slow down thinning and terminus retreat of chhota shigri glacier are expected over the next years conversely the 2003 2004 ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier wide mass balance is zero given the limited velocity change between 1987 1989 and 2003 2004 and the small terminus change between 1988 and 2010 we suggest that the glacier has experienced a period of near zero or slightly positive mass balance in the 1990s before shifting to a strong imbalance in the 21st century this result challenges the generally accepted idea that glaciers of western himalaya have been shrinking rapidly for the last decades

synergistic approach for mapping debris covered glaciers using optical thermal remote sensing data with inputs from geomorphometric parameters abstract debris cover on glacier boundaries critically impedes the global inventorying of glaciers and confounds most of the techniques developed for semi automated mapping of glaciers debris on the glacier referred as supraglacial debris and that occurring outside the glacier boundaries referred as periglacial debris being derived from a common source i e the valley rock tend to have a similar spectral response in the reflection region which renders them mutually indistinguishable however there exist temperature differences between them this aspect has been considered in this remote sensing based study to distinguish between the supraglacial and periglacial debris in a test area in the chenab basin himalayas by inclusion of thermal infrared tir bands in remote sensing data processing a synergistic multisensor approach for the delineation of debris covered glacier boundaries is used here which integrates the inputs from thermal terra aster sensor and optical irs p6 awifs sensor remote sensing data multispectral classification techniques and the dem derived geomorphometric parameters the results of this study corroborate earlier findings on utilization of temperature differences as one of the parameters in glacial studies the proposed synergistic approach therefore appears useful in accurate mapping of debris covered glaciers in the himalayan region

response of debris covered glaciers in the mount everest region to recent warming and implications for outburst flood hazards abstract in areas of high relief many glaciers have extensive covers of supraglacial debris in their ablation zones which alters both rates and spatial patterns of melting with important consequences for glacier response to climate change wastage of debris covered glaciers can be associated with the formation of large moraine dammed lakes posing risk of glacier lake outburst floods glofs in this paper we use observations of glaciers in the mount everest region to present an integrated view of debris covered glacier response to climate change which helps provide a long term perspective on evolving glof risks in recent decades debris covered glaciers in the everest region have been losing mass at a mean rate of 0 32 m yr 1 although in most cases there has been little or no change in terminus position mass loss occurs by 4 main processes 1 melting of clean ice close to glacier elas 2 melting beneath surface debris 3 melting of ice cliffs and calving around the margins of supraglacial ponds and 4 calving into deep proglacial lakes modelling of processes 1 and 2 shows that everest region glaciers typically have an inverted ablation gradient in their lower reaches due to the effects of a down glacier increase in debris thickness mass loss is therefore focused in the mid parts of glacier ablation zones causing localised surface lowering and a reduction in downglacier surface gradient which in turn reduce driving stress and glacier velocity so the lower ablation zones of many glaciers are now stagnant model results also indicate that increased summer temperatures have raised the altitude of the rain snow transition during the summer monsoon period reducing snow accumulation and ice flux to lower elevations as downwasting proceeds formerly efficient supraglacial and englacial drainage networks are broken up and supraglacial lakes form in hollows on the glacier surface ablation rates around supraglacial lakes are typically one or two orders of magnitude greater than sub debris melt rates so extensive lake formation accelerates overall rates of ice loss most supraglacial lakes are perched above hydrological base level and are susceptible to drainage if they become connected to the englacial drainage system speleological surveys of conduits show that large englacial voids can be created by drainage of warm lake waters along pre existing weaknesses in the ice roof collapses can open these voids up to the surface and commonly provide the nuclei of new lakes thus by influencing both lake drainage and formation englacial conduits exert a strong control on surface ablation rates an important threshold is crossed when downwasting glacier surfaces intersect the hydrological base level of the glacier base level lakes formed behind intact moraine dams can grow monotonically and in some cases can pose serious glof hazards glacier termini can evolve in different ways in response to the same climatic forcing so that potentially hazardous lakes will form in some situations but not others additionally the probability of a flood is not simply a function of lake volume but depends on the geometry and structure of the dam and possible trigger mechanisms such as ice or rockfalls into the lake satellite based measurements of glacier surface gradient and ice velocities allow probable future locations of base level lakes to be identified a base level lake has begun to grow rapidly on ngozumpa glacier west of mount everest and could attain a volume of 10 8 m 3 within the next 2 or 3 decades unless mitigation efforts are undertaken this lake could pose considerable glof hazard potential

spatially variable response of himalayan glaciers to climate change affected by debris cover the present state and future evolution of himalayan glaciers has been controversial an analysis of remotely sensed frontal changes and surface velocities from glaciers in the greater himalaya between 2000 and 2008 shows large regional variability in the responses of himalayan glaciers to climate change

present and future states of himalaya and karakoram glaciers a complete glacier inventory of the himalaya and karakoram h k has been created by merging records from the chinese glacier inventory several regional inventories produced by the international centre for integrated mountain development kathmandu nepal and partial inventories from the geological survey of india the only remaining gap the indian part of kashmir has been filled by a reconnaissance inventory based on soviet military maps at 1 200 000 scale representing the late 1970s it contains records for 3526 glaciers covering 9584 km 2 the new h k inventory contains records and outlines for 20 812 glaciers covering 43 178 km 2 the extent of ice in the karakoram is slightly less than in the himalaya but the karakoram glaciers are on average twice as thick 160 m as against 80 m a glacier by glacier analysis relying on estimates of mass balance for the entire mountain range and on an extension of the often used volume area scaling relation suggests that up to about one fifth of the glaciers present in 1985 may have disappeared already if mass loss were to remain constant at the average rate for 1975 2008 from 3000 to 13 000 more glaciers might disappear by 2035 if mass loss were to continue to accelerate as inferred for 1985 2008 only a few thousand to a few hundred glaciers might remain in 2035 total area and total mass would each decrease by about one half constant rate assumption or three quarters constant trend assumption these projections which are uncertain and neglect some possibly important mitigating controls such as variable extents of debris cover and the feedback due to retreat to higher elevations demonstrate the need for more complete analyses to inform public perceptions of and policy decisions relating to the health of h k glaciers

quantification of everest region glacier velocities between 1992 and 2002 using satellite radar interferometry and feature tracking quincey d j luckman a benn d 2009 quantification of everest region glacier velocities between 1992 and 2002 using satellite radar interferometry and feature tracking journal of glaciology 55 192 596 606 sponsorship knowledge transfer project no 3742

structural evolution of the frontal fold thrust belt nw himalayas from sequential restoration of balanced cross sections and its hydrocarbon potential abstract two sedimentary lithotectonic zones are traditionally recognized in the northwestern himalayan frontal fold thrust belt in the nahan salient the lesser himalaya zone lhz and the sub himalaya zone shz the lhz is made up of a sequence of proterozoic to early cambrian rocks and the shz is made up of cenozoic rock sequences which were deposited subsequent to the india asia collision serial balanced cross sections show that the structural geometries become increasingly complex from independent ramp anticlines near the foreland through imbricate fan duplex to stacked up horses towards the hinterland sequential restoration suggests a structural evolution in which a foreland propagating in sequence thrusting event was followed by out of sequence thrusting in an approximately break back style during the out of sequence movement some of the ramps formed during in sequence thrusting were repeatedly reactivated leading to very complex structural geometries particularly in the lhz in such a complexly deformed terrain a rigorous structural modelling approach combined with a robust geochemical and geochronological database should be used to carry out calibrated petroleum system modelling and thus reduce exploration risk

assessing the status of glaciers in part of the chandra basin himachal himalaya a multiparametric approach this study investigates the change in multiple glacier parameters of three valley type glaciers sakchum sc chhota shigri cs and bara shigri bs located in chandra basin himachal himalaya sharing the same climatic regime and assesses the control of nonclimatic factors on wholesome glacier response multitemporal satellite remote sensing data from landsat tm etm oli 1993 2014 and terra aster 2002 2014 along with an srtm digital elevation model were used for extraction of the glacier parameters results show that while sc and bs retreated sc 10 65 2 52 m y bs 15 51 2 52 m y and lost area sc 0 49 0 0032 km2 bs 1 18 0 0032 km2 the cs remained relatively stable retreat rate 4 06 2 52 m y area loss 0 19 0 0032 km2 during 1993 2014 however results of surface ice velocities siv change sc 24 41 cs 21 60 and bs 28 49 and surface elevation change sc 1 22 m y cs 0 91 m y and bs 1 21 m y suggest a comparable slowing down and surface lowering from 2002 to 2014 debris cover also varied substantially sc 30 25 cs 11 96 bs 19 61 on these glaciers results reveal that higher retreat deglaciation of glaciers was associated with higher altitudinal range slow siv in lower ablation zones laz and glacier hypsometry debris cover on glaciers was found to be controlled by slope higher deglaciation rates higher siv in the upper ablation zone uaz coupled with lower siv in laz and surface lowering glacier siv was primarily governed by slope gradient differential surface lowering and size of accumulation zone acz the siv results confirm the presence of stagnant zones in the lower ablations of sc 1 km upstream and bs 6 km upstream and a major siv dropdown in the uaz sc 34 48 bs 37 35 indicating the expansion of stagnant zones farther up glacier surface lowering seemed to be influenced by ice flux changing spatial distribution of debris cover presence of supraglacial lakes and ice cliffs bordering them melting around supraglacial lakes and backwasting of ice cliffs may be the prime reasons behind intense mass loss observed in the stagnant zone of the bara shigri glacier where surface lowering was 32 higher than glacier wide thinning differential surface lowering in glaciers reduced the surface gradient and hence the siv also rapid surface gradient changes and siv dropdown in the sakchum glacier indicate possible development of supraglacial lakes on it in the future interestingly despite close proximity sc cs and bs demonstrate three distinct ablation patterns reemphasizing the role of nonclimatic factors overall the study states that mutual variation of glacier parameters together with nonclimatic factors exercise a great control on glacier response

evolution of a debris covered glacier in the western himalaya during the last four decades 1971 2016 a multiparametric assessment using remote sensing and field observations abstract this study assesses the response of the panchi nala glacier bhaga basin western himalaya to climate change by monitoring multiple glacier parameters namely length area debris cover snowline altitude sla surface ice velocity siv and surface elevation change h these parameters were analysed using high resolution satellite images corona kh 4b and sentinel 2 msi and medium resolution ones landsat tm etm oli and terra aster acquired between 1971 and 2016 along with extensive field observations considering only dimensional changes the glacier appears to have low rates of recession 4 54 2 56 m y 1 and deglaciation 0 11 0 04 y 1 over the study period 1971 2016 however siv and h values reveal a significant slowdown 33 87 1992 93 2015 16 and an extensive lowering 1 62 0 06 m y 1 2000 2013 on the glacier the debris cover area and sla also increased by 23 50 1 74 and 287 63 m respectively during 1971 2016 increase in the mean winter minimum temperature and decrease in the winter snowfall are probably the main drivers of glacier depletion we conclude that the significant slowdown extensive surface lowering development of a proglacial lake and appearance of the supraglacial lakes collectively indicate a severe glacier degeneration this forewarns that the glacier may experience an accelerated pace of wastage in the future

glacier change 1958 1998 in the north cascades national park complex washington usa the spatial characteristics for all glaciers in the north cascades national park complex usa were estimated in 1958 and again in 1998 the total glacier area in 1958 was 117 3 1 1 km 2 by 1998 the glacier area had decreased to 109 1 1 1 km 2 a reduction of 8 2 0 1 km 2 7 estimated volume loss during the 40 year period was 0 8 0 1 km 3 of ice this volume loss contributes up to 6 of the august september stream flow and equals 16 of the august september precipitation no significant correlations were found between magnitude of glacier shrinkage and topographic characteristics of elevation aspect or slope however the smaller glaciers lost proportionally more area than the larger glaciers and had a greater variability in fractional change than larger glaciers most of the well studied alpine glaciers are much larger than the population median so global estimates of glacier shrinkage based on these well studied glaciers probably underestimate the true magnitude of regional glacier change

debris thickness patterns on debris covered glaciers abstract many debris covered glaciers have broadly similar debris thickness patterns surface debris thickens and tends to transition from convex to concave up down glacier we explain this pattern using theory analytical and numerical models paired with empirical observations down glacier debris thickening results from the conveyor belt like nature of the glacier surface in the ablation zone debris can typically only be added but not removed and from the inevitable decline in ice surface velocity toward the terminus down glacier thickening of debris leads to the reduction of sub debris melt and debris emergence toward the terminus convex up debris thickness patterns occur near the up glacier end of debris covers where debris emergence dominates ablation controlled concave up debris thickness patterns occur toward glacier termini where declining surface velocities dominate velocity controlled a convex concave debris thickness profile inevitably results from the transition between ablation control and velocity control down glacier debris thickness patterns deviating from this longitudinal shape are most likely caused by changes in hillslope debris supply through time by establishing this expected debris thickness pattern the effects of climate change on debris cover can be better identified

estimation of debris cover and its temporal variation using optical satellite sensor data a case study in chenab basin himalaya debris cover over glaciers greatly affects their rate of ablation and is a sensitive indicator of glacier health this study focuses on estimation of debris cover over samudratapu glacier chenab basin himalaya using optical remote sensing data remote sensing image data of irs 1c liss iii september 2001 irs p6 awifs september 2004 and terra aster september 2004 along with survey of india topographical maps 1963 were used in the study supervised classification of topographically corrected reflectance image data was systematically conducted to map six land cover classes in the glacier terrain snow ice mixed ice and debris debris valley rock and water an accuracy assessment of the classification was conducted using the aster visible near infrared data as the reference the overall accuracies of the glacier cover maps were found to range from 83 7 to 89 1 whereas the individual class accuracy of debris cover mapping was found to range from 82 to 95 this shows that supervised classification of topographically corrected reflectance data is effective for the extraction of debris cover in addition a comparative study of glacier cover maps generated from remote sensing data supervised classification of september 2001 and september 2004 and survey of india topographical maps 1963 has highlighted the trends of glacier depletion and recession the glacier snout receded by about 756 m from 1963 to 2004 and the total glacier area was reduced by 13 7 km 2 from 110 km 2 in 1963 further glacier retreat is found to be accompanied by a decrease in mixed ice and debris and a marked increase in debris cover area the area covered by valley rock is found to increase confirming an overall decrease in the glacier area the results from this study demonstrate the applicability of optical remote sensing data in monitoring glacier terrain and particularly mapping debris cover area

distribution of debris thickness and its effect on ice melt at hailuogou glacier southeastern tibetan plateau using in situ surveys and aster imagery debris cover is widely present in glacier ablation areas of the tibetan plateau and its spatial distribution greatly affects glacier melt rates high resolution in situ measurements of debris thickness on hailuogou glacier mount gongga southeastern tibetan plateau show pronounced inhomogeneous debris distribution an analysis of transverse and longitudinal profiles indicates that the ground surveyed debris thicknesses and advanced spaceborne thermal emission and reflection radiometer aster derived thermal resistances of debris layers correlate strongly over the entire ablation area across and along glacier patterns of aster derived thermal resistance correspond well with spatial patterns of debris thickness which may reflect large scale variations in the extent and thickness of the debris cover the ice melt rate variability over the ablation area simulated by a surface energy balance model that considered thermal resistance of the debris layer indicates clearly the crucial role of debris and its spatial continuity in modifying the spatial characteristics of melt rates because of the inhomogeneous distribution of debris thickness about 67 of the ablation area on hailuogou glacier has undergone accelerated melting whereas about 19 of the ablation area has experienced inhibited melting and the sub debris melt rate equals the bare ice melt rate in only 14 of the ablation area

four years of mass balance on chhota shigri glacier himachal pradesh india a new benchmark glacier in the western himalaya little is known about the himalayan glaciers although they are of particular interest in terms of future water supply regional climate change and sea level rise in 2002 a long term monitoring programme was started on chhota shigri glacier 32 2 n 77 5 e 15 7 km2 6263 4050 m a s l 9 km long located in lahaul and spiti valley himachal pradesh india this glacier lies in the monsoon arid transition zone western himalaya which is alternately influenced by asian monsoon in summer and the mid latitude westerlies in winter here we present the results of a 4 year study of mass balance and surface velocity overall specific mass balances are mostly negative during the study period and vary from a minimum value of 1 4 m w e in 2002 03 and 2005 06 equilibrium line altitude ela 5180 m a s l to a maximum value of 0 1 m w e in 2004 05 ela 4855 m a s l chhota shigri glacier seems similar to mid latitude glaciers with an ablation season limited to the summer months and a mean vertical gradient of mass balance in the ablation zone debris free part of 0 7 m w e 100 m 1 similar to those reported in the alps mass balance is strongly dependent on debris cover exposure and the shading effect of surrounding steep slopes

the potential of satellite radar interferometry and feature tracking for monitoring flow rates of himalayan glaciers abstract the stagnation of himalayan glaciers will only be exacerbated by a warming climate increasing hazards associated with glacier lake development frontal recession is a poor indicator of negative balance in this region where most glaciers are debris covered but reduced glacier flow rates provide a valuable warning of stagnation in situ measurements of velocity are understandably rare and remote sensing measurements have hitherto been limited by severe topography and lack of suitable data in this paper we compare two techniques to measure flow rates in everest region glaciers firstly satellite radar interferometry sri has recently become more viable because of improved digital elevation data and precision orbit models which now allow snapshots of velocities to be retrieved from ers imagery in the mid 1990s without ground control information secondly feature tracking between synthetic aperture radar sar images is found to be successful even on the small glaciers of this region because of the patterning associated with debris cover this technique extends through the 1990s and beyond the time frame over which velocities can be measured using the examples of the khumbu glacier flowing south into nepal and the kangshung glacier flowing east into china from the everest massif we compare sri and sar feature tracking in ers images consider the errors in these techniques and examine the potential to monitor flow rates across the region the techniques are found to be highly complementary and appropriate for monitoring flow rates in this region suggesting that routine monitoring of himalayan glaciers is possible the kangshung glacier appears to sustain relatively high flow rates of up to 10 cm day which along with a convex topographic profile indicates a healthy glacier not exhibiting significant negative mass balance in comparison much of the khumbu glacier appears to have stagnated the surface velocity at gorak shep is only 20 of a field based measurement in the 1970 s and the concave surface profile confirms the downwasting associated with a debris covered glacier in recession

the glaciers climate change initiative methods for creating glacier area elevation change and velocity products glaciers and their changes through time are increasingly obtained from a wide range of satellite sensors due to the often remote location of glaciers in inaccessible and high mountain terrain satellite observations frequently provide the only available measurements furthermore satellite data provide observations of glacier characteristics that are difficult to monitor using ground based measurements thus complementing the latter in the glaciers cci project of the european space agency esa three of these characteristics are investigated in detail glacier area elevation change and surface velocity we use a data from optical sensors to derive glacier outlines b digital elevation models from at least two points in time c repeat altimetry for determining elevation changes and d data from repeat optical and microwave sensors for calculating surface velocity for the latter the two sensor types provide complementary information in terms of spatio temporal coverage while c and d can be generated mostly automatically a and b require the intervention of an analyst largely based on the results of various round robin experiments multi analyst benchmark studies for each of the products we suggest and describe the most suitable algorithms for product creation and provide recommendations concerning their practical implementation and the required post processing for some of the products area velocity post processing can influence product quality more than the main processing algorithm

recent rapid thinning of the mer de glace glacier derived from satellite optical images the rapid wastage of mountain glaciers and their contribution to sea level rise require worldwide monitoring of their mass balance in this paper we show that changes in glacier thickness can be accurately measured from satellite images we use spot image pairs to build digital elevation models dems of the mont blanc area french alps for different years to register the dems we adjust their longitude latitude and altitude over motionless areas the uncertainty of the thickness change measurement is greatly reduced by averaging over areas covering altitude intervals of 50 m comparisons with topographic profiles and a differential dem from aerial photographs obtained on the mer de glace indicate an overall accuracy of 1 m for the thickness change measurement below 2100 m satellite dems show an evolution of the thinning rate from 1 0 4 m a years 1979 1994 to 4 1 1 7 m a 2000 2003

stagnation and mass loss on a himalayan debris covered glacier processes patterns and rates the ablation areas of debris covered glaciers typically consist of a complex mosaic of surface features with contrasting processes and rates of mass loss this greatly complicates glacier response to climate change and increases the uncertainty of predictive models in this paper we present a series of high resolution dems and repeat lake bathymetric surveys on ngozumpa glacier nepal to study processes and patterns of mass loss on a himalayan debris covered glacier in unprecedented detail most mass loss occurs by melt below supraglacial debris and melt and calving of ice cliffs backwasting although ice cliffs cover only 5 of the area of the lower tongue they account for 40 of the ablation the surface debris layer is subject to frequent re distribution by slope processes resulting in large spatial and temporal differences in debris layer thickness enhancing or inhibiting local ablation rates and encouraging continuous topographic inversion a moraine dammed lake on the lower glacier tongue spillway lake underwent a period of rapid expansion from 2001 to 2009 but later experienced a reduction of area and volume as a result of lake level lowering and sediment redistribution rapid lake growth will likely resume in the near future and may eventually become up to 7 km long

glacier changes in the karlik shan eastern tien shan during 1971 72 2001 02 glacier changes in the karlik shan eastern tien shan from 1971 72 to 2001 02 were monitored in this study topographic maps of 1 50000 scale based on aerial photographs from 1971 72 and satellite images landsat tm landsat etm and aster from 1992 2001 and 2002 were used to map glacier extent through a process of manual digitizing the total glacier area decreased by 5 3 from 1971 72 to 2001 02 the rate of glacier area shrinkage was 0 13 a 1 between 1972 and 1992 but it was 0 27 a 1 from 1992 to 2001 02 suggesting accelerated glacier retreat in recent decades glacier changes in the region are a response to summer temperature increase annual precipitation also showed an upward trend but this could not compensate for the mass loss due to ablation

consideration of the errors inherent in mapping historical glacier positions in austria from the ground and space 1893 2001 the historical record of in situ measurements of the terminus positions of the pasterze and kleines fleiskees glaciers in the eastern alps of austria is used to assess uncertainties in the measurement of decadal scale changes using satellite data topographic maps beginning in 1893 and satellite data from 1976 to 2001 were studied in concert with ground measurements to measure glacier changes ground measurements show that the tongue of the pasterze glacier receded f1150 m from 1893 to 2001 while satellite derived measurements using august 2001 landsat enhanced thematic mapper plus etm data registered to an 1893 topographic map show a recession of 1300 1800 m with an unknown error the measurement accuracy depends on the registration technique and the pixel resolution of the sensor when two satellite images are used when using topographic maps an additional source of error is the accuracy of the glacier position shown on the map between 1976 and 2001 landsat derived measurements show a recession of the terminus of the pasterze glacier of 479f136 m at an average rate of 19 1 m a 1 while measurements from the ground showed a recession of 428 m at an average rate of 17 1 ma 1 four meter resolution ikonos satellite images from 2000 and 2001 reveal a shrinkage of 22 096f46 m 2 in the pasterze tongue the nearby kleines fleiskees glacier lost 30 of its area between 1984 and 2001 and the area of exposed ice increased by 0 44f0 0023 km 2 according to landsat satellite measurements as more recent satellite images are utilized especially data that are geocoded the uncertainty associated with measuring glacier changes has decreased it is not possible to assess the uncertainty when an old topographic map and a satellite image are coregistered

limitations in identifying the equilibrium line altitude from the optical remote sensing derived snowline in the tien shan china optical remote sensing derived end of summer snowline altitude sla has long been employed on glaciers as an indicator of the equilibrium line altitude ela in the tien shan northwest china both accumulation and ablation of glaciers occur mainly in the warm season making it difficult to obtain the representative snowline highest snowline in the area the high spatio temporal resolution of hj 1 satellite images enables the highest snowline to be acquired in this paper we compare image derived sla and measured in situ ela for two adjacent glaciers in the tien shan over the period 2009 10 results indicate that 1 in 2009 there was a substantial difference between sla and ela on one glacier suggesting inconsistent applicability in using sla to identify ela over a large area and 2 in 2010 an intense ablation year the field data derived ela surpassed the glacier peak in this situation there is no theoretical relationship between sla and ela and the image derived snowline actually indicates the boundary between ice and firn from previous years in summary errors will arise from the discrepancies between individual glaciers and from intensive ablation when using sla to identify ela over a large area

glacier surface velocities in alpine terrain from optical satellite imagery accuracy improvement and quality assessment the worldwide retreat of mountain glaciers has important consequences for the water food and power supply of large and densely populated areas in south and central asia successful mitigation of the hydrological impacts on societies as well as assessing glacier related hazards require large scale monitoring of glacier dynamics however detailed glaciological data from the asian highlands are lacking due to its size and difficult accessibility we have applied a novel technique for precise orthorectification co registration and sub pixel correlation of advanced spaceborne thermal emission and reflection radiometer aster satellite imagery to derive surface velocities of himalayan glaciers our approach allows for the correction of offsets due to attitude effects and sensor distortions as well as elevation errors if a digital elevation model dem from the shuttle radar topography mission srtm was used for orthorectification after post processing the error on the displacements is on the order of 2 4 m per correlation translated into annual velocities this error is reduced increased when the correlated images are more less than a year apart through application of a filtering procedure and several quality tests the consistency of the results is validated to provide confidence in the remotely sensed velocity measurements despite the lack of ground control this novel approach allows fast easy and economically viable acquisition of detailed glaciological data in areas of difficult access and provides a means for large scale monitoring of glaciers in high mountainous terrain

using atmospherically corrected landsat imagery to measure glacier area change in the cordillera blanca peru from 1987 to 2010 abstract the dynamic tropical glaciers of the peruvian cordillera blanca are rapidly changing and these changes are expected to affect water availability especially during the dry season in this study we quantify recent changes to these water reservoirs providing estimates of glacier area in the cordillera blanca and sub watersheds of the rio santa for the following years 1987 1996 2004 and 2010 we explore the effects of atmospheric and topographic corrections by comparing debris free glacier area estimates generated using raw scenes and corrected scenes our results suggest that these corrections can have a significant impact on debris free glacier area estimates when the same threshold is applied debris free glacier area estimates derived from uncorrected scenes are approximately 5 less than debris free glacier area estimates derived from atmospherically corrected scenes we determined that debris free glacier area estimates are most sensitive to the choice of threshold and topographic effects to map glacier area change we used high resolution satellite imagery to calibrate our selection of a single threshold for the normalized difference snow index ndsi this threshold value was applied to all ndsi images which were derived from four carefully selected and atmospherically corrected landsat thematic mapper tm scenes acquired at the end of the dry season in order to calculate total glacier area we manually mapped debris covered glaciers because automated methods were unsuccessful in this region as of august 2010 the cordillera blanca had a total glacier area of 482 km 2 which amounts to a 25 decrease since 1987 glaciers in the southern portions of the cordillera blanca which have lower median elevations on average lost a greater percentage of their area from 1987 to 2010 relative to their northern counterparts overall glacier area change in the cordillera blanca appears to be accelerating between 2004 and 2010 glaciers in the cordillera blanca lost area at a rate that was approximately 3 5 times the average rate of area loss from 1970 to 2003

decadal changes in glacier parameters in the cordillera blanca peru derived from remote sensing we present spatial patterns of glacier fluctuations from the cordillera blanca peru glacier area terminus elevations median elevations and hypsography at decadal timescales derived from 1970 aerial photography 2003 spot5 satellite data geographic information systems gis and statistical analyses we derived new glacier outlines from the 2003 spot images and ingested them in the global land and ice measurements from space glims glacier database we examined changes in glacier area on the eastern and western side of the cordillera in relation to topographic and climate variables temperature and precipitation results include 1 an estimated glacierized area of 569 6 21 km 2 in 2003 2 an overall loss in glacierized area of 22 4 from 1970 to 2003 3 an average rise in glacier terminus elevations by 113 m and an average rise in the median elevation of glaciers by 66 m showing a shift of ice to higher elevations especially on the eastern side of the cordillera and 4 an increase in the number of glaciers which indicates disintegration of ice bodies annual air temperature showed a significant upward trend in the last 30 years with larger temperature increases at lower elevations there was a slight but not significant decrease in precipitation our results are consistent with glacier retreat and warming trends noted in the last three decades in the tropics

detection of snow ice cover changes using subpixel based change detection approach over chhota shigri glacier western himalaya india abstract mapping and monitoring of the glacier changes over different regions of earth surface is a challenging task due to regional rugged topography and climate conditions this study focused on the monitoring of snow or ice cover changes over chhota shigri glacier western himalaya india a subpixel based change detection scd approach is proposed aiming to identify the transition zones mixed pixels between the two class categories the scd approach involves the integration of subpixel classification and change vector analysis cva to define the changes in the form of magnitude and direction between two multitemporal dates at the subpixel level to check the efficacy of proposed scd experimental outcomes have also been compared with existing neural network nn based scd nn scd the result analysis has shown that proposed scd achieved better accuracy 84 80 as compared to nn scd 78 80 in addition a time series data was acquired using the landsat series landsat 5 7 and 8 as per availability to perform the trend analysis over chhota shigri glacier during the period 2001 2019 this study offers the effective way of estimating the bi temporal snow ice changes especially over rugged terrains around the globe

planimetric and volumetric glacier changes in the khumbu himal nepal since 1962 using corona landsat tm and aster data multitemporal space imagery from 1962 corona kh 4 1992 landsat tm 2001 and 2005 terra aster was used to investigate the glacier changes in the khumbu himal nepal the ice coverage in the investigation area decreased by about 5 between 1962 and 2005 with the highest retreat rates occurring between 1992 and 2001 the debris coverage increased concomitantly with the decrease in total glacier area the clean ice area decreased by 10 digital terrain model dtm generation from the early corona kh 4 stereo data in this high relief terrain is time consuming and the results still contain some elevation errors however these are minor in the snow free areas with gentle slopes thus comparison of the surfaces of the debris covered glacier tongues based on the corona dtm and an aster dtm is feasible and shows the downwasting of the debris covered glaciers the highest downwasting rates more than 20 m 0 5 m a 1 can be found near the transition zone between the active and the stagnant glacier parts of the debris covered glacier tongues the downwasting is lower but still evident in the active ice areas and at the snout with thick debris cover all investigated debris covered glaciers in the study area show similar behaviour the estimated volume loss for the investigated debris covered glacier tongues is 0 19 km 3

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

large surface velocity fluctuations of biafo glacier central karakoram at high spatial and temporal resolution from optical satellite images despite global warming and unlike their himalayan neighbours glaciers in the karakoram mountains do not show signs of significant retreat here we report high velocity variations of biafo glacier central karakoram which occurred between 2001 and 2009 and which indicate considerable dynamics in its flow behaviour we have generated a dense time series of glacier surface velocities based on cross correlation of optical satellite images which clearly shows seasonal and interannual velocity variations reaching 50 in some places the interannual velocity variations resemble the passing of a broad wave of high velocities with peak velocities during 2005 and some diffusion down glacier over a period of at least 4 years high interannual velocity variations are also observed at other glaciers in the vicinity suggesting a common cause although these appear to partly comprise longer acceleration phases analysis of weather station data provides some indications of meteorological conditions that could have promoted sustained sliding events during this period but this does not explain the wave like nature of the acceleration at biafo glacier and the regular protracted velocity changes