automated detection of unstable glacier flow and a spectrum of speedup behavior in the alaska range surge type glaciers are loosely defined as glaciers that experience periodic alterations between slow and fast flow regimes glaciers from a variety of mountain ranges around the world have been classified as surge type yet consensus of what defines a glacier as surge type has not always been met a common source of dispute is the lack of a succinct and globally applicable delimiter between a surging and nonsurging glacier the attempt is often a boolean classification however glacier speedup events can vary significantly with respect to event magnitude duration and the fraction of the glacier that participates in the speedup for this study we first updated the inventory of glaciers that show flow instabilities in the alaska range and then quantified the spectrum of speedup behavior we developed a new method that automatically detects glaciers with flow instabilities our automated results show a 91 success rate when compared to direct observations of speedup events and glaciers that are suspected to display unstable flow based on surface features through a combination of observations from the landsat archive and previously published data our inventory now contains 36 glaciers that encompass at least one branch exhibiting unstable flow and we document 53 speedup events that occurred between 1936 and 2014 we then present a universal method for comparing glacier speedup events based on a normalized event magnitude metric this method provides a consistent way to include and quantify the full spectrum of speedup events and allows for comparisons with glaciers that exhibit clear surge characteristics yet have no observed surge event to date our results show a continuous spectrum of speedup magnitudes from steady flow to clearly surge type which suggests that qualitative classifications such as surge type or pulse type behavior might be too simplistic and should be accompanied by a standardized magnitude metric

characterizing the surge behavior of alakesayi glacier in the west kunlun shan northwestern tibetan plateau from remote sensing data between 2013 and 2018

karakoram glacier surge dynamics quincey d j braun m glasser n f bishop m p hewitt k luckman a 2011 geophysical research letters 38 article number l18504

application of image cross correlation to the measurement of glacier velocity using satellite image data abstract image to image cross correlation software is applied to pairs of digital satellite images to map the velocity field of moving ice this technique uses small scale glacial surface features such as crevasse scars and snow dunes as markers on the surface of the moving ice displacements of the surface features are mapped by selecting small image areas centered on distinct features or by dividing a large area of densely featured glacial surface into a grid of areas and searching a subsequent image for matching areas using a cross correlation algorithm interpolation of the peak correlation values allows the displacements to be measured to subpixel accuracy resulting in very precise velocity measurements cross correlation is also applied to provide image coregistration in areas devoid of bedrock exposures in such areas subtle large scale topographic undulations in the ice surface related to underlying bedrock structure may be correlated by using large image areas and low pass filtered images both types of applications are demonstrated using ice stream d and ice stream e in west antarctica as test areas a high resolution map of the velocity field of the central portion of ice stream e generated by the displacement measuring technique is presented the use of cross correlation software is a significant improvement over previous manually based photogrammetric methods for velocity measurement and is far more cost effective than in situ methods in remote polar areas

the impact of ground based glaciogenic seeding on clouds and precipitation over mountains a case study of a shallow orographic cloud with large supercooled droplets this paper examines the impact of ground based glaciogenic seeding on a shallow lightly precipitating orographic cloud with rather large 35 m supercooled droplets the storm was observed on 22 february 2012 as part of the agi silver iodide seeding cloud impact investigation experiment in wyoming the cloud base top temperature was about 5 c 12 c vertical velocity data from an airborne doppler w band 3 mm profiling wyoming cloud radar wcr indicate broad ascent due to the strong wind 20 m s 1 impinging on the terrain and small pockets of intense updrafts the large droplets low droplet and ice particle concentrations and strong updrafts lead to natural snow growth mainly by accretion riming the treated seeded period is compared with the preceding untreated period the main target site located on a mountain pass was impacted by agi seeding according to a trace chemistry analysis of the falling snow data from three radar systems were used in the analysis of the impact of seeding on snow growth the wcr two ka band 1 2 cm profiling micro rain radars and an x band 3 cm scanning polarization doppler on wheels radar this case is complicated somewhat by a natural increase in cloud liquid water and in snow growth by riming starting halfway during the seeding period and continuing after seeding ended composite data from the centimeter wave radar systems indicate an increase in low level reflectivity during seeding even after accounting for the natural trend observed in the upwind control region a precipitation particle probe at the main target site shows an increase in concentration of both small and large hydrometeors

observations on the distribution and characteristics of potholes on surging glaciers potholes are depressions often water filled 10 100 m across found on the surfaces of glaciers most fields of potholes are found on surging glaciers suggesting that potholes form as a result of surging a photographic inventory of hundreds of glaciers in alaska and yukon territory allowed this hypothesis to be tested out of 26 pothole fields observed 19 were on known surging glaciers two on probable surging glaciers and the rest in areas where surging glaciers are common the majority of pothole fields were found near the equilibrium line photographs show that potholes formed within several years following the 1937 surge of the black rapids glacier in a zone where there had been intense crevassing between 1949 and 1986 the total number of potholes on the glacier decreased from approximately 700 to less than 200 while their mean size increased from 20 to 30 m some of these potholes have been observed to drain englacially the movement of these potholes were measured photogrammetrically to be less than 10 m yr the majority of the motion resulting from ice flow intense crevassing resulting from surging appears to be necessary for the formation of potholes but not sufficient as only 21 out of 256 surging glaciers contain potholes

saltating particles playa crusts and dust aerosols at owens dry lake california as part of the multinational lake owens dust experiment lode we have studied the generation of dust storms on the south sand sheet of owens dry lake california an anthropogenically desiccated playa reported to be the single greatest source of particulate matter in north america during march 1993 we performed an intensive field study including eight significant dust storms building on our prior work 1978 1984 and preliminary studies 1991 1992 we studied sources and magnitude of coarse saltating particles the meteorological conditions that allow them to become mobile across the flat playa of owens dry lake and how the motion of saltating particles across different types of playa surfaces results in the generation of pm10 dusts aerosol particles smaller than 10 m aerodynamic diameter saltating grains of lacustrine sand and broken crust abrade and disaggregate the playa surface into fine aerosols and the resulting pm10 concentrations recorded during major dust storms are among the highest ever recorded in north america on 23 march 1993 we measured a 2 h concentration on the playa of 40 620 g m 3 as far as we can determine the highest ambient pm10 value ever recorded in the u s a abrasion of salt silt clay crusts by saltation is shown to be responsible for all but a small part of one dust storm the quantity sand run saltating particle transport multiplied by wind run is shown to be very closely correlated with dust aerosol concentration finally we have established that on lake bed studies are essential for quantitative prediction of dust events on the owens dry lake bed despite the difficult conditions encountered

criteria for the recognition of salt pan evaporites layered evaporites can accumulate in 1 ephemeral saline pans 2 shallow perennial lagoons or lakes and 3 deep perennial basins criteria for recognizing evaporites deposited in these settings have yet to be explicitly formulated the characteristics of the ephemeral saline pan setting have been determined by examining eight holocene halite dominated pans salt pans and their deposits marine and non marine from the u s mexico egypt and bolivia these salt pans are typified by alternating periods of flooding resulting in a temporary brackish lake evaporative concentration when the lake becomes saline and desiccation which produces a dry pan fed only by groundwater the resulting deposits consist of alternating layers millimetres to decimetres of halite and mud the layers of halite are characterized by 1 vertical and horizontal cavities rounded crystal edges and horizontal truncation surfaces due to dissolution during flooding 2 vertical chevrons and cornets grown syntaxially on the bottom during the saline lake stage 3 halite cements overgrowths and euhedral cavity linings and disruption of layering into metre scale polygons produced during the desiccation stage the muddy interbeds are characterized by displacive growth of halite during the desiccation stage immediately below the surface of the pan the halite layers are matured by repeated episodes of dissolution and diagenetic crystal growth this results in porous crusts with patches of chevron and cornet crystals truncated by dissolution clear diagenetic halite cement and internal sediment these layers of mature halite closely resemble the patchy cloudy and clear textures of ancient halite deposits holocene salt pans are known to cover thousands of square kilometres and cap halite deposits hundreds of metres thick so they are realistic models for ancient evaporites in scale e g permian salado formation of new mexico texas which preserves many primary salt pan features

groundwater in the celtic regions this book covers a diverse range of hydrogeological environments that occur in the celtic regions of britain and ireland these include hard rock aquifers of lower palaeozoic and precambrian age generally dominated by fracture flow within a shallow zone of weathering carboniferous limestone aquifers often characterized by conduit flows in karstic systems dual porosity permo triassic sandstone aquifers and quaternary deposits many of which form shallow granular aquifers the papers presented here address a number of current issues common to the celtic regions including groundwater protection policies groundwater management in karst aquifers groundwater development in quaternary aquifers groundwater evaluation in data scarce aquifers and groundwater supplies to small island communities

eolian sediments generated by anthropogenic disturbance of playas human impacts on the geomorphic system and geomorphic impacts on the human system abstract in many of the earth s arid and semiarid lands saline lakes playas and similar landforms are disturbed as a result of human activity diversion and or consumptive use of surface or groundwaters has created the effect of a climate change in numerous drainage basins resulting in the desiccation of lakes and reactivation of eolian processes at many locations playas are natural sites for extensive eolian activity because of the deposition of clastic and chemical sediments in basins by surface water via fluvial transport and groundwater via efflorescence wind erosion and deposition of playa sediments has had a major role in the development of landforms and sedimentary units in the present lunette fields worldwide simpson desert australia and geological past from the triassic mercia mudstone england to the quaternary lahontan basin and cima volcanic field usa anthropogenic disturbance or desiccation of playa systems has resulted in the eolian transport of sand e g lop nor china konya basin turkey rajasthan india kappakoola australia several sites in west africa and or dust e g aral sea kazakhstan uzbekistan old wives lake canada kara bogaz gol ex ussr lake texcoco mexico owens dry lake mono lake and other playas usa typically this is accomplished by abstraction of water and or removal of vegetation from terminal lake basins an extensive review of the literature documents many examples and or potential examples of such phenomena in numerous nations the reactivation of eolian processes from closed basins produces air pollution in the form of fugitive dust naturally occurring compounds released into the atmosphere by human actions and has significant environmental and economic impacts on human activities in the surrounding areas restoration or mitigation of degraded land on or surrounding playas has been accomplished at lake texcoco kara bogaz gol and the konya basin and is being actively implemented at mono lake owens dry lake and the aral sea

surges of glaciers in iceland surges are common in all the major ice caps in iceland and historical reports of surge occurrence go back several centuries data collection and regular obser vationover thelast several decadeshave permitteda detailed descriptionof several surges fromwhich it is possible to generalize onthe nature of surging in icelandic glaciers com bining the historical records of glacier front variations and recent field research we sum marize the geographic distribution of surging glaciers their subglacial topography and geology the frequency andduration of surges changes in glacier surface geometry during the surge cycle and measured velocity changes comparedto calculatedbalance velocities wenotetheindicatorsofsurgeonsetanddescribechangesinice waterandsedimentfluxes duringa surge surgesaccomplishasignificantfractionofthetotalmasstransportthrough the main outlet glaciers of ice caps in iceland and have important implications for their hydrology ouranalysisof the data suggeststhat surge type glaciersin icelandarecharac terizedbygentlysloping surfacesandthatthey movetoo slowlytoremain inbalance given their accumulation rate surge frequency is neither regular nor clearly related to glacier size or massbalance steeply sloping glaciers whetherhard or soft bedded seemto move sufficiently rapidly to keep inbalance with the annual accumulation

marine like potash evaporite formation on a continental playa case study from chott el djerid southern tunisia abstract an exceptional flood in january 1990 led to the formation of a large ephemeral lake on the chott el djerid a salt playa in southern tunisia repeated observations made during 1990 show that the ephemeral lake underwent four evolutionary stages 1 initial flooding 2 evaporative concentration of lake waters 3 the movement of concentrated brine pools over the playa surface as a result of wind action and 4 total desiccation of the lake by september 1990 during all four stages the brine chemistry of the lake was monitored water inflow into the chott el djerid basin was found to have a consistent ca so 4 cl rich and hco 3 co 3 poor chemistry reflecting the recycling of homogeneous assemblages of cretaceous mio pliocene and quaternary evaporites within the catchment as the ephemeral lake shrank these waters produced an na mg k cl so 4 brine which was similar to modern sea water mineral saturation data show that during the desiccation of the lake saturation with respect to both gypsum and halite was achieved and that the most concentrated brines were ultimately saturated with respect to potash phases after the desiccation of the lake the main mineral phases found on the chott included gypsum and halite in addition ephemeral deposits of carnallite observed as carnallitite 3kmgcl 3 6h 2 0 nacl were found this assemblage is that which would be expected to form if the waters had undergone salt norm evaporation at 1 bar pressure at 25 c snorm in the evaporation model proposed by jones and bodine 1987 the nature of both the brine chemistry and evaporite mineralogy provides a new and rare example of marine like potash bearing evaporites being formed in a contemporary continental playa

surface area changes of glaciers in the tibetan plateau interior area since the 1970s using recent landsat images and historical maps the tibetan plateau interior area tpia often termed the qangtang plateau is distinguished by many dome like mountains higher than 6000 m a s l these mountains provide favourable conditions for the development of ice caps and glaciers of extreme continental subpolar type according to historical topographic maps 1959 80 and recent landsat images 2004 11 continuous retreat was observed and the glacierized part of this area decreased by 9 5 0 27 a 1 with respect to the total glacier area of 8036 4 km 2 in the 1970s glaciers in the zhari namco basin have experienced the highest area shrinkage with a reduction rate of 0 72 a 1 while the smallest reduction occurred in bangong co 0 12 a 1 and dogai coying basins 0 11 a 1 a regional gradient of area loss was found with a larger decrease in the south and a smaller decrease in the north of the plateau comparisons indicate glaciers have experienced smaller shrinkage in the tpia than in surrounding regions glacier shrinkage in the tpia is mainly attributed to an increase in air temperature while precipitation glacier size and positive difference of glaciation also played an important role

the new remote sensing derived swiss glacier inventory ii first results complete swiss glacier inventories are available for 1850 reconstructed and 1973 from aerial photography connected to the global land ice measurements from space project a new swiss glacier inventory for approximately the year 2000 sgi 2000 is compiled mainly based on satellite imagery the developed and applied remotesensing and geographical information system gis methods are described in part i of the contribution in part ii the inventory design first result analyses and comparisons with former glacial conditions are presented as basic entries sgi 2000 contains the individual glacier identification planimetric glacier boundaries as derived from image analysis digitized central flowlines and polygonal glacier basin maps all other parameters are automatically deduced from the above entries and a digital elevation model within a gis here we analyze a set of small bernese and valais glaciers of area 2 these glaciers lost about 21 of area from 1973 to 1998 in addition to about 80 during 1850 1973 both with respect to the 1973 area in order to track the latest trend in more detail anintermediate glacier condition has been compiled from satellite imagery of 1985 this analysis gave an increasing speed of area loss 19 for 1985 98

heterogeneity in karakoram glacier surges many karakoram glaciers periodically undergo surges during which large volumes of ice and debris are rapidly transported downglacier usually at a rate of 1 2 orders of magnitude greater than during quiescence here we identify eight recent surges in the region and map their surface velocities using cross correlation feature tracking on optical satellite imagery in total we present 44 surface velocity data sets which show that karakoram surges are generally short lived lasting between 3 and 5 years in most cases and have rapid buildup and relaxation phases often lasting less than a year peak velocities of up to 2 km a 1 are reached during summer months and the surges tend to diminish during winter months otherwise they do not follow a clearly identifiable pattern in two of the surges the peak velocity travels down ice through time as a wave which we interpret as a surge front three other surges are characterized by high velocities that occur simultaneously across the entire glacier surface and acceleration and deceleration are close to monotonic there is also no consistent seasonal control on surge initiation or termination we suggest that the differing styles of surge can be partly accounted for by individual glacier configurations and that while some characteristics of karakoram surges are akin to thermally controlled surges elsewhere e g svalbard the dominant surge mechanism remains unclear we thus propose that these surges represent a spectrum of flow instabilities and the processes controlling their evolution may vary on a glacier by glacier basis

landsat based inventory of glaciers in western canada 1985 2005 abstract we report on a glacier inventory for the canadian cordillera south of 60 n across the two western provinces of british columbia and alberta containing 30 000 km2 of glacierized terrain our semi automated method extracted glacier extents from landsat thematic mapper tm scenes for 2005 and 2000 using a band ratio tm3 tm5 we compared these extents with glacier cover for the mid 1980s from high altitude aerial photography for british columbia and from landsat tm imagery for alberta a 25 m digital elevation model dem helped to identify debris covered ice and to split the glaciers into their respective drainage basins the estimated mapping errors are 3 4 and arise primarily from seasonal snow cover glaciers in british columbia and alberta respectively lost 10 8 3 8 and 25 4 4 1 of their area over the period 1985 2005 the region wide annual shrinkage rate of 0 55 a 1 is comparable to rates reported for other mountain ranges in the late twentieth century least glacierized mountain ranges with smaller glaciers lost the largest fraction of ice cover the highest relative ice loss in british columbia 24 0 4 6 occurred in the northern interior ranges while glaciers in the northern coast mountains declined least 7 7 3 4

glacier mass changes over duxueshan burog kangri and zangser kangri in the inner tibetan plateau the variation of glacier mass balance during the past decades remains poorly known for duxueshan burog kangri and zangser kangri dbz which are located in the inner tibetan plateau itp a transition zone with shifting influences between the westerlies and the indian summer monsoon in the present study glacier area and mass changes were determined by topographic maps topo landsat imagery and multi temporal digital elevation models dems generated with topo srtm tandem x bistatic interferometric synthetic aperture radar insar images and high mountain asia 8 m dems on average the glaciers showed a slight retreat from 343 27 5 23 km2 in 1971 to 334 67 3 21 km2 in 2018 0 05 0 04 a 1 however glaciers lost mass at a rate of 0 32 0 03 m w e a 1 from 1971 to 2012 for the 1999 2012 and 2012 2017 periods mass balances of 0 03 0 16 and 0 09 0 04 m w e a 1 respectively were observed which represents an approximately equilibrium two glaciers also advanced in our investigation period and we confirmed one of them surged in 2015

ice velocity and climate variations for baltoro glacier pakistan quincey dj copland l mayer c bishop m luckman a belo m 2009 ice velocity and climate variations for the baltoro glacier pakistan journal of glaciology 55 194 1061 1071 sponsorship rcuk us national science foundation us national geographic society natural sciences and engineering research council of canada canadian foundation for innovation ontario research fund university of ottawa

evidence of liquid dependent ice nucleation in high latitude stratiform clouds from surface remote sensors 1 ground based lidar radar and microwave radiometer observations at eureka canada barrow alaska and over the western arctic ocean measure physical characteristics and morphology of stratiform clouds despite transition of a cold atmosphere 15 c through ice supersaturated conditions ice is not observed until soon after a liquid layer several cases illustrating this phenomenon are presented in addition to long term observations from three measurement sites characterizing cloud phase frequency this analysis demonstrates that clouds composed entirely of ice occur less frequently than liquid topped mixed phase clouds at temperatures warmer than 25 to 30 c these results indicate ice formation generally occurs in conjunction with liquid at these temperatures and suggest the importance of liquid dependent ice nucleation mechanisms

hubbard glacier alaska 2002 closure and outburst of russell fjord and postflood conditions at gilbert point 1 hubbard glacier the largest temperate tidewater glacier in the world has been advancing since 1895 ad and has now twice dammed 60 km long russell fjord once in 1986 and more recently in 2002 this paper focuses on the 2002 event when a strong spring advance pushed shallow submarine proglacial sediments against gilbert point closing off russell fjord by late june as a consequence upstream ice flow decelerated from 5 m d 1 to 1 5 m d 1 with flow diverging to either side of gilbert point lake height reached 15 m asl before intense rains caused lake water to overtop the moraine dam on 14 august 2002 three cubic kilometers of water were released within 30 hours with peak discharge reaching 55 000 m3 s 1 24 hours after the flood began the discharge records for the 1986 and 2002 outbursts differ significantly and reflect differences in lake height 26 m versus 15 m and dam types ice versus moraine the 2002 outburst proceeded in two stages 1 relatively slow overtopping of the subaerial moraine with downward erosion rates of 1 2 m h 1 with little lateral expansion 2 followed by faster downward erosion of the submarine moraine up to 7 m h 1 with rapid lateral expansion of the channel by ice calving 7 m h 1 the annual average terminus position at gilbert point has remained constant since 2002 although there are seasonal variations of 100 200 m the deep channel strong tidal currents and seasonally warm ocean water appear to have prevented the advance of this segment of the terminus despite the glacier s continued advance elsewhere along its terminus sediments are slowly filling in the channel at a rate of about 4 m yr 1 and their steady accumulation may eventually trigger the next closure

characteristics of surge type glaciers glaciers can be divided into two classes according to their flow behavior normal relatively steady annually averaged flow rate and surge type pronounced cyclic flow variations having a typical periodicity of 10 100 years we have examined the population statistics of 2356 glaciers in the st elias mountains yukon territory canada and estimate that 151 6 4 of these glaciers are surge type to explore how various glacier attributes are associated with surging we compare the probability of surging associated with various subsets of the complete population to appropriate reference values in this way potential influences on surge tendency can be examined for the 55 drainage basins analyzed there is a pronounced spatial variation in the concentration of surge type glaciers but no obvious environmental control can be evinced within the study area the greatest concentration lies in the northern st elias mountains a region of high topographic elevation that is experiencing rapid tectonic uplift analysis of the influence of length on surge tendency reveals that long glaciers have a significantly greater probability of being surge type than short glaciers the surge probability increases monotonically from 0 61 for very short glaciers 0 1 km to 65 1 for long glaciers 10 75 km this result suggests that ice sheets and ice caps or at least portions of them should have a high probability of surging tributary glaciers have a greater tendency to surge than trunk glaciers presumably because they may themselves be surge type and may additionally participate in surges of the trunk glacier the nonrandom geographical distribution of surge type glaciers is not simply a consequence of the variation from basin to basin of the glacier length distribution surge type glaciers tend to have a higher overall elevation than normal glaciers the elevation of the highest point of the accumulation zone the elevation of the snow line and the elevation of the lowest point of the ablation zone on average exceed the corresponding elevations for normal glaciers there is no significant difference between the overall slopes of surge type and normal glaciers although there is a tendency for surge type glaciers to have greater slope in the accumulation zone and lesser slope in the ablation zone than normal glaciers although the prevalent flow direction for glaciers in the yukon data set is to the north surge type glaciers tend to flow to the east and southeast this orientation influence is probably explained by the fact that many of the longest glaciers also flow to the east and southeast

monitoring surging glaciers of the pamirs central asia from space the evolution of surging glaciers of the pamirs central asia has been studied using repeat remote sensing surveys in the institute of geography russian academy of sciences since the early 1970s we use images obtained from national resurs f satellites 1972 91 as well as landsat 7 and terra 1999 2006 to provide a basis for monitoring of surging glaciers aimed at developing their inventory studying the causes and mechanisms of surges and examining the timing and extent of glacial catastrophes the inventory from the early 1990s allows identification of 215 glaciers with a dynamically unstable regime we discovered 51 surging glaciers up until 2006 10 more surges had occurred we use stereoscopic deciphering and photogrammetric processing of consecutive satellite images to study the morphology and ice velocity changes of several compound surging glaciers we analyze the results of monitoring of bivachny and oktyabr sky glaciers from 1972 to 1991 and sugran glacier from 1972 to 2006 two surges of sugran glacier occurred during this time an internal surge in 1976 80 and a surge with glacier tongue advance as far as 4 5 km in 2000 05 the role of damming in compound glacier systems is examined satellite based monitoring is now the only method for obtaining initial information about the state and fluctuations of such glaciers

svalbard surge dynamics derived from geometric changes geometric changes on a sample of svalbard glaciers were studied using subtraction of repeat digital terrain models to determine early surge stage dynamics changes in surface features were also analyzed a number of new surges were found for glaciers not known to have surged previously the surge development could be followed through three stages of which the first two had not been previously described in svalbard the first two stages are mainly identified from glacier thickness changes and showed little visual evidence in stage 1 initial surface lowering was found in the upper part of the glacier followed by a thickening further down glacier in stage 2 stage 3 represents the period of well developed surge dynamics that is usually reported some surges ceased at stage 2 as a partial surge and never developed into a fully active surge these partial surges could be misinterpreted as rapid response to climate change the results of this study further support previous findings that the majority of svalbard glaciers are of surge type data archives have greatly facilitated the search for signs of surges and the recapturing of the course of events in this paper we present a number of new observations of svalbard surge type behaviour based on evidence from geometric changes and complemented by observations of newly developed crevasse fields two criteria are used to identify a surge either individually or in combination 1 mass displacement from the upper to the lower glacier part and 2 presence of new crevasse fields which indicate rapid or strong changes in stresses the aims of our study are to contribute to a more complementary picture and better understanding of the transition from build up stage via initial surge dynamics to the previously described mature stage where the changes are more pronounced we also investi gate whether all surges develop fully the implications of partial surges for interpretation of surface lowering related to varying climate conditions and finally the large spread in estimates for the number of surge type glaciers in svalbard

influence of glacier advance on the development of the multipart riffeltal rock glacier central austrian alps the multipart riffeltal rock glacier located in a tributary valley of the kaunertal tyrol austria is investigated to enlarge the knowledge about spatial and temporal development of rock glaciers in and at the margins of pro glacial areas and to get a better understanding of glacier rock glacier interactions the subject of interest consists of a complex system of two adjacent rock glacier tongues and various superposed lobes with differing ages origin and root zones and therefore diverse development to determine the reasons for their diverging development the internal structure and permafrost occurrence on and in the surrounding area of the rock glacier were studied by application of geomorphological mapping geophysical methods and measurement of the basal temperature of the winter snow cover bts permafrost modelling was performed on the basis of bts data and land surface parameters derived from a high resolution airborne laser scanning als digital elevation model dem additionally the als data were used to measure vertical and horizontal changes of the rock glacier surface between 2006 and 2012 glacier rock glacier interactions during and since the little ice age lia are evident for the development of the studied rock glacier a geomorphic map gives important information about the connection between glacial advance or retreat and permafrost or ground ice occurrence the combination of all information helps in the analysis of diverse kinematic action of neighbouring rock glacier tongues copyright 2014 john wiley sons ltd

characterizing the may 2015 karayaylak glacier surge in the eastern pamir plateau using remote sensing we investigate an internal surge of karayaylak glacier which was reported by the media in may 2015 to differentiate the may 2015 glacier surge from other glacier advances we surveyed changes in velocity crevasses and glacier area using landsat 8 oli l1t zy 1 02c and gaofen 1 images from october 2014 to july 2015 the velocity measured by automatic feature extraction and tracking during the active phase was 10 100 times the velocity during the quiescent phase with a maximum of 20 2 0 9 m d 1 mean standard error from 8 to 15 may 2015 in the west branch of the glacier the surge initiation and termination took place from 13 april to 16 june 2015 ice in the west branch length 7 km area 6 8 km 2 of karayaylak glacier accelerated down to the east branch leading to the development of crevasses and ice covering an additional 0 1 km 2 of summer pasture on the northwestern side however we detected no advance of the glacier s terminus

how much do we really know about glacier surging some of the ideas about glacier surging are considered mainly but not entirely in the light of observations of temperate glaciers in alaska u s a made within the last 15 years climate has an influence on surge recurrence interval climate and weather also affect surge initiation termination and magnitude regional studies lead to the speculation that subglacial till plays a key role in surging and it has been found under all surge type glaciers studied so far including black rapids and variegated glaciers alaska in most of the glaciers studied till deformation processes dominate the motion in quiescence the linked cavity model of surge triggering and rapid motion is not consistent with these observations but the limited coverage of the observations does not rule it out under parts of the glaciers studied the till observations in alaska raise old questions about the interaction between till and the hydraulic systems of temperate glaciers the role of stored water which observations show to be active even in winter on black rapids glacier is noted

glacier motion estimation using sar offset tracking procedures two image to image patch offset techniques for estimating feature motion between satellite synthetic aperture radar sar images are discussed intensity tracking based on patch intensity cross correlation optimization and coherence tracking based on patch coherence optimization are used to estimate the movement of glacier surfaces between two sar images in both slant range and azimuth direction the accuracy and application range of the two methods are examined in the case of the surge of monacobreen in northern svalbard between 1992 and 1996 offset tracking procedures of sar images are an alternative to differential sar interferometry for the estimation of glacier motion when differential sar interferometry is limited by loss of coherence i e in the case of rapid and incoherent flow and of large acquisition time intervals between the two sar images in addition an offset tracking procedure in the azimuth direction may be combined with differential sar interferometry in the slant range direction in order to retrieve a two dimensional displacement map when sar data of only one orbit configuration are available

the origin of ice in mountain cap clouds abstract ice crystal development in relatively simple layer clouds was studied using airborne instrumentation the patterns in the development of ice in those clouds suggest that the ice originates in association with the initial condensation process near the upwind edge of the cloud since continued ice production does not occur beyond that region the ice development can be attributed to nucleation there is no evidence for secondary ice generation either condensation freezing or contact nucleation could account for the observed nucleation process but special properties are required for the nuclei in either case ice crystal concentrations show a clear temperature trend as expected for a nucleation process

glacier velocities across the central karakoram optical matching of aster advanced spaceborne thermal emission and reflection radiometer satellite image pairs is used to determine the surface velocities of major glaciers across the central karakoram the aster images were acquired in 2006 and 2007 and cover a 60 120 km region over baltoro glacier pakistan and areas to the north and west the surface velocities were compared with differential global position system gps data collected on baltoro glacier in summer 2005 the aster measurements reveal fine details about ice dynamics in this region for example glaciers are found to be active over their termini even where they are very heavily debris covered the characteristics of several surge type glaciers were measured with terminus advances of several hundred meters per year and the displacement of trunk glaciers as surge glaciers pushed into them this study is the first synthesis of glacier velocities across this region and provides a baseline against which both past and future changes can be compared

the 2008 09 surge of central yulinchuan glacier northern tibetan plateau as monitored by remote sensing the 2008 09 surge of central yulinchuan glacier cyg on the northwestern slope of muztag mountain tibetan plateau is studied based on satellite remote sensing the widely used cross correlation feature tracking method was used to collect satellite image control points and validate their geometric accuracies as well as to derive glacier surface velocity changes in glacier length and area were also retrieved results show that the surge of cyg initiated in may 2008 and terminated in july 2009 two diffluent glacier termini advanced 590 26 m 5 1 0 2 of the 2004 length and 182 26 m 1 8 0 3 respectively and glacier area increased by similar to 1 41 0 11 km 2 4 6 0 4 of the 2004 area during this period the most significant surge period was october 2008 to march 2009 when most of the terminus advances and area increases occurred the glacier surface drastically crevassed during this time as much as 1657 297 m of horizontal surface displacements were produced by surge ice and maximum surface speed reached 13 1 5 m d 1 results of transverse and longitudinal velocity profiles revealed two surge waves during this surge of cyg

the new remote sensing derived swiss glacier inventory i methods a new swiss glacier inventory is to be compiled from satellite data for the year 2000 the study presented here describes two major tasks 1 an accuracy assessment of different methods for glacier classification with landsat thematic mapper tm data and a digital elevation model dem 2 the geographical information system gis based methods for automatic extraction of individual glaciers from classified satellite data and the computation of three dimensional glacier parameters such as minimum maximum and median elevation or slope and orientation by fusion with a dem first results obtained by these methods are presented in part ii of this paper kaab and others 2002 thresholding of a ratio image from tm4 and tm5 reveals the best suited glacier map the computation of glacier parameters in a gis environment is efficient and suitable for worldwide application the methods developed contribute to the u s geological survey led global land ice measurements from space glims project which is currently compiling a global inventory of land ice masses within the framework of global glacier monitoring haeberli and others 2000

glacier surges in the north west west kunlun shan inferred from 1972 to 2017 landsat imagery the west kunlun shan lie close to or are perhaps part of two significant glaciological phenomena the high mountain asia surge supercluster and the karakoram anomaly however glaciological studies and particularly surge studies in the range are limited here we extend the database of known surges in the region using landsat imagery and cross correlation feature tracking we examine 88 glaciers larger than 1 km2 in the hotan prefecture of xinjiang china and find evidence of nine surges occurring between 1972 and 2017 glaciers display low active phase velocities 0 2 1 5 km a 1 that show seasonal acceleration in the summer active phase periods as short as 2 years and build up and deceleration phases of months years although these observations display characteristics indicative of both the classic hydrological and thermal switch mechanisms the surging observed displays a close resemblance to that in the adjacent karakoram ranges furthermore the majority of the surges occur clustered at the end of a decadal scale warming period corroborating previously proposed causal links between climate and surging in the karakoram we suggest that the two regions should be considered part of one larger system when considering surge dynamics in high mountain asia

visible and near infrared digital images for determination of ice velocities and surface elevation during a surge on osbornebreen a tidewater glacier in svalbard

dust emission from wet and dry playas in the mojave desert usa the interactions between playa hydrology and playa surface sediments are important factors that control the type and amount of dust emitted from playas as a result of wind erosion the production of evaporite minerals during evaporative loss of near surface ground water results in both the creation and maintenance of several centimeters or more of loose sediment on and near the surfaces of wet playas observations that characterize the texture mineralogic composition and hardness of playa surfaces at franklin lake soda lake and west cronese lake playas in the mojave desert california along with imaging of dust emission using automated digital photography indicate that these kinds of surface sediment are highly susceptible to dust emission the surfaces of wet playas are dynamic surface texture and sediment availability to wind erosion change rapidly primarily in response to fluctuations in water table depth rainfall and rates of evaporation in contrast dry playas are characterized by ground water at depth consequently dry playas commonly have hard surfaces that produce little or no dust if undisturbed except for transient silt and clay deposited on surfaces by wind and water although not the dominant type of global dust salt rich dusts from wet playas may be important with respect to radiative properties of dust plumes atmospheric chemistry windborne nutrients and human health published in 2007 by john wiley sons ltd

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

glacier surge mechanism 1982 1983 surge of variegated glacier alaska the hundredfold speedup in glacier motion in a surge of the kind the kind that took place in variegated glacier in 1982 1983 is caused by the buildup of high water pressure in the basal passageway system which is made possible by a fundamental and pervasive change in the geometry and water transport characteristics of this system the behavior of the glacier in surge has many remarkable features which can provide clues to a detailed theory of the surging process the surge mechanism is akin to a proposed mechanism of overthrust faulting

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

observation of playa salts as nuclei in orographic wave clouds during the ice in clouds experiment layer clouds ice l dry lakebed or playa salts from the great basin region of the united states were observed as cloud nuclei in orographic wave clouds over wyoming using a counterflow virtual impactor in series with a single particle mass spectrometer sodium potassium magnesium calcium chloride salts were identified as residues of cloud droplets importantly these salts produced similar mass spectral signatures to playa salts with elevated cloud condensation nuclei ccn efficiencies close to sea salt using a suite of chemical characterization instrumentation the playa salts were observed to be internally mixed with oxidized organics presumably produced by cloud processing as well as carbonate these salt particles were enriched as residues of large droplets 19 m compared to smaller droplets 7 m in addition a small fraction of silicate containing playa salts were hypothesized to be important in the observed heterogeneous ice nucleation processes while the high ccn activity of sea salt has been demonstrated to play an important role in cloud formation in marine environments this study provides direct evidence of the importance of playa salts in cloud formation in continental north america has not been shown previously studies are needed to model and quantify the impact of playas on climate globally particularly because of the abundance of playas and expected increases in the frequency and intensity of dust storms in the future due to climate and land use changes

a surge of north gasherbrum glacier karakoram china between 2003 and 2007 north gasherbrum glacier on the northeastern slope of the karakoram mountains in asia underwent a dramatic acceleration during which a velocity wave propagated down the glacier there was a significant transfer of ice from up glacier downstream which resulted in a strong surface elevation increase over the lower tongue but only a moderate advance of the glacier snout we interpret this behaviour as that of a glacier surge and we explain the observations by means of a simple version of the kamb drainage switching theory

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