multi model photogrammetric analysis of the 1990s surge of sortebrae east greenland sortebrae is a surge type tidewater glacier complex draining southeastward from the geikie plateau east greenland sortebrae s main flow unit surged around 1950 and again between 1992 and 1995 the 1990s surge affected the lower 50 km of sorte brae over an area of approximately 335 km2 over a period of 5 km surge velocities in the order of kilometres per annum are about 100 fold the quiescent velocities multi model photogrammetric analysis shows a thinning of the reservoir zone of up to 219 m and thickening of the receiving zone of up to 74 m the surge transported approximately 18 6 km 3 of ice down glacier the total calving volume as a result of the surge amounted to 11 7 km 3 equivalent to a calving flux of 3 9 7 3 km a 1 the surge characteristics and environmental setting suggest that the surge mechanism involves a switch in the subglacial drainage this surge of sortebrae is more similar to the fast short alaskan type surges than to the sluggish long svalbard type surges

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

the structural geometric and volumetric changes of a polythermal arctic glacier during a surge cycle comfortlessbreen svalbard various parameters of the most recent surge of the polythermal glacier comfortlessbreen in northwest svalbard have been assessed through a combination of remote sensing and ground observations analysis of a digital elevation model time series shows a marked change in the geometry of the glacier from quiescence 1990 and earlier into the late surge phase 2009 the transfer of 0 74 km3 of ice caused up to 80 m of surface drawdown in the reservoir area above the equilibrium line whilst ice built up in a spatially concentrated manner in the receiving zone below the equilibrium line a ramp of ice c 100 m above quiescent level developed in the lower reaches of the glacier late in the surge also in the lower reaches of the glacier structures attributable to the passage of a kinematic wave are identified and the migration of a surge front on the glacier is thus inferred in a conceptual model we consider that a bend in the valley in which the glacier resides and convergence with tributary glaciers to be significant factors in the style of surge evolution their flow restrictive interference results in slow initial mass transfer and the growth of a surge front within 3 4 km of the terminus copyright 2015 john wiley sons ltd

combination of srtm3 and repeat aster data for deriving alpine glacier flow velocities in the bhutan himalaya abstract the present study evaluates the fusion of dems from the advanced spaceborne thermal emission and reflection radiometer aster instrument and the shuttle radar topography mission srtm the study area consists of high elevation glaciers draining through the rough topography of the bhutan himalayas it turns out that the aster derived and srtm3 dems have similar accuracy over the study area but the srtm3 dem contains less gross errors however for rough topography large sections of the srtm3 dem contain no data we therefore compile a combined srtm3 aster dem from this final composite master dem we produce repeat aster orthoimages from which we evaluate the dem quality and derive glacier surface velocities through image matching the glacier tongues north of the himalayan main ridge which enter the tibet plateau show maximum surface velocities in the order of 100 200 m year 1 in contrast the ice within the glacier tongues south of the main ridge flows with a few tens of meters per year these findings have a number of implications among others for glacier dynamics glacier response to climate change glacier lake development or glacial erosion the study indicates that space based remote sensing can provide new insights into the magnitude of selected surface processes and feedback mechanisms that govern mountain geodynamics

the 13c record for atmospheric co2 what is it trying to tell us abstract records of the 13c to 12c ratio of atmospheric co2 13catm trapped in antarctic ice may offer important insights into past changes in the carbon cycle and drivers of past fluctuations in atmospheric pco2 a recently published record offers the highest resolution 13catm record to date covering the last deglaciation schmitt et al 2012 two features are of particular interest one is the small magnitude 0 15 0 05 of the 13catm difference between the last glacial maximum lgm and the holocene the other is the abrupt drop 0 30 0 05 in 13catm between 17 5 and 16 0 ka this drop is coincident with that of dust deposition on the antarctic ice cap and into the ocean off south australia consistent with the hypothesis that increased efficiency of southern ocean nutrient utilization during the last glacial period and the consequent reduction in atmospheric pco2 was driven in part by dust related iron fertilization however in order to further explore either the small lgm holocene difference or the rapid drop during the early deglaciation 13catm changes related to the lgm cooling the lgm upper ocean 13c change ocean circulation changes and the lgm change in the photosynthetic fractionation factor must be known as each is currently the subject of a sizable uncertainty we present only a roadmap regarding what must be done in order to interpret the schmitt et al 2012 record

measuring snow and glacier ice properties from satellite satellite remote sensing is a convenient tool for studying snow and glacier ice allowing us to conduct research over large and otherwise inaccessible areas this paper reviews various methods for measuring snow and glacier ice properties with satellite remote sensing these methods have been improving with the use of new satellite sensors like the synthetic aperture radar sar during the last decade leading to the development of new and powerful methods such as sar interferometry for glacier velocity digital elevation model generation of ice sheets or snow cover mapping some methods still try to overcome the limitations of present sensors but future satellites will have much increased capability for example the ability to measure the whole optical spectrum or sar sensors with multiple polarization or frequencies among the methods presented are the satellite derived determination of surface albedo snow extent snow volume snow grain size surface temperature glacier facies glacier velocities glacier extent and ice sheet topography in this review emphasis is put on the principles and theory of each satellite remote sensing method an extensive list of references with an emphasis on studies from the 1990s allows the reader to delve into specific topics

quiescent phase dynamics and surge history of a polythermal glacier hessbreen svalbard hessbreen is a 5 km 2 polythermal glacier in southern spitsbergen it is believed to have surged at the end of the 19th century and another surge started in 1969 not in 1972 as earlier studies suggested the surge was probably triggered in the middle section of the glacier and affected the upper part approximately 4 years before including the whole glacier present velocities are low increasing from 0 3 m a 1 at the snout to 4 8 m a 1 above the equilibrium line a distinct velocity reduction occurs where the glacier narrows this suggests the velocities here are affected by the cold marginal and frontal ice large seasonal variations with summer velocities of more than twice the winter velocities in the middle part of the glacier indicate a seasonal change in the drainage system in this area in the lower part there is no apparent sliding the balance flux estimate indicates that the actual ice flux is only about 50 of that required for steady state so hessbreen appears to be building up in the accumulation area the surge duration is now estimated to be 8 years

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

svalbard glacier elevation changes and contribution to sea level rise 1 we compare satellite altimetry from the ice cloud and land elevation satellite icesat 2003 2007 to older topographic maps and digital elevation models 1965 1990 to calculate long term elevation changes of glaciers on the svalbard archipelago results indicate significant thinning at most glacier fronts with either slight thinning or thickening in the accumulation areas except for glaciers that surged which show thickening in the ablation area and thinning in the accumulation areas the most negative geodetic balances occur in the south and on glaciers that have surged while the least negative balances occur in the northeast and on glaciers in the quiescent phase of a surge cycle geodetic balances are related to latitude and to the dynamical behavior of the glacier the average volume change rate over the past 40 years for svalbard excluding austfonna and kvitoya is estimated to be 9 71 0 55 km3 yr 1 or 0 36 0 02 m yr 1 w equivalent for an annual contribution to global sea level rise of 0 026 mm yr 1 sea level equivalent

distortion of isochronous layers in ice revealed by ground penetrating radar in addition to measuring ice sheet thickness ground penetrating radar can be used to delineate reflections in ice sheets1 2 3 these reflections are generally accepted to result from layers of isochronous deposition of snow and can reveal much about the dynamics of the ice flow here we present ground penetrating radar data from fletcher promontory antarctica which show arches and troughs in isochronous ice layers to a depth of 100 m we demonstrate that the origin of these features can be determined by their growth with depth and many features result from local anomalies in accumulation rate which can be correlated with the ice surface slope one arch appears to be the result of a local anomaly in vertical strain rate its proximity to the ice divide width and growth with depth indicate that this arch is one of a class of features postulated by raymond4 but not previously shown to exist in the field such a feature is an indication of the nonlinear rheology of ice and requires that palaeoclimate records from ice cores extracted from the vicinity of ice divides underlain by similar features should be specifically corrected for such effects on ice flow

tidewater glacier surges initiated at the terminus terrasar x data were provided by dlr project oce1503 and funded by the conoco phillips lundin northern area program through the crios project calving rates and impact on sea level c n acknowledges funding from european union erc grant 320816 and esa project glaciers cci 4000109873 14 i nb

dynamics of tidewater surge type glaciers in northwest svalbard the evolution of ice dynamics through surges of four tidewater terminating glaciers in northwest svalbard is investigated by remote sensing a 20 year time series of glacier surface flow speeds and frontal positions is presented covering the recent surges of monacobreen comfortlessbreen blomstrandbreen and fjortende julibreen surface flow speeds were derived using feature tracking between pairs of ers sar and alos palsar images while frontal positions were taken from the same imagery as well as more frequent but lower spatial resolution envisat wide swath mode images during all four surges increased ice flow caused the tidewater margin to advance while the calving flux was initially reduced to near zero due to compressive stresses limiting crevasse propagation as ice speed decreased the terminus continued to advance until the glacier s speed had returned to its pre surge flow rate only at this time did the terminus start to retreat and peak iceberg calving flux was established we conclude that terminus advance closely tracks glacier speed up that there is little mass loss through calving during the most active phase of the surge and that seasonal cycles of terminus positions diminish during the active surge phase

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

ground based interferometric radar for velocity and calving rate measurements of the tidewater glacier at kronebreen svalbard this paper presents the first attempt to measure the calving rate and flow velocity of the front of a glacier using ground based high range resolution interferometric radar at a high temporal rate 2 hz the radar operating at 5 75 ghz is located 4 km from the calving front of kronebreen svalbard the radar measures a horizontal width of 700 m of the front and a range of 300 m the latter includes the calving front and 250 m up glacier we find that the glacier surface provides permanent scatterers so spatially continuous movements at the front and at locations further up glacier can be tracked for 8 hours we measured a large increase in velocity at the calving front which extended 30 m up glacier while further up glacier the velocity was stable 2 5 m d 1 during the entire period two large calving events were identified during this survey removing 25 m of ice in the radar range direction normal to the ice front the velocity of the front slowed to a stable 2 5 m d 1 after the events during another data series the velocities were stable 2 5 m d 1 and no calving events were identified the method is promising for carrying out studies of processes at a calving front as it provides spatially continuous high frequency accurate velocities from a safe distance to the glacier

rock glacier dynamics in southern carpathian mountains from high resolution optical and multi temporal sar satellite imagery the dynamics of rock glaciers in marginal periglacial environments are poorly understood especially in eastern europe where the enhanced continentality produces a distinct pattern of periglacial phenomena multi temporal image analysis of high resolution optical and radar satellite imagery of the southern carpathian mountains romania revealed the small dynamic nature and a slow geomorphologic evolution of rock glaciers over a 46 yr period of record 1968 2014 nine rock glaciers located in glacial cirques and troughs within the central area of retezat mountain were included in this study overall the estimated displacement rates are extremely low i e a few cm year compared with other active rock glaciers from all over the world despite their relative attenuated activity it appears that judele valea rea and pietrele are still active rock glaciers but in an evident disequilibrium imbalance with the actual climate these findings document the lowest altitude and easternmost active rock glaciers at this latitude from europe quantitative investigations were concentrated on pietrele rock glacier subject of recent field campaigns optical data analysis indicated a slight acceleration of the horizontal velocities at the surface of pietrele rock glacier in recent years this acceleration appears to be caused by an increase in the temperature of permafrost resulting from an evident warming of external air temperature radar data analysis suggested seasonal variability of surface motion with higher deformation in autumn whereas in early summer or spring the deformation is negligible overall the results obtained with cross correlation analysis interferometric synthetic aperture radar insar coherence analysis and small baseline subset sbas multitemporal interferometry are consistent displaying similar deformation patterns with the highest creep rates located in the southern and western portions of the glacier these findings are supported by thermal and geophysical measurements which suggest the probable presence of permafrost within these areas the observed displacements were interpreted as permafrost creep and their very low velocity rates suggest the deforming frozen layers are very thin these results provide i baseline information and decadal scale trends and a ii strategy for future monitoring of the health and integrity of the rock glacier environment in the carpathian mountains

glacier crevasses observations models and mass balance implications we review the findings of approximately 60 years of in situ and remote sensing studies of glacier crevasses as well as the three broad classes of numerical models now employed to simulate crevasse fracture the relatively new insight that mixed mode fracture in local stress equilibrium rather than downstream advection alone can introduce nontrivial curvature to crevasse geometry may merit the reinterpretation of some key historical observation studies in the past three decades there have been tremendous advances in the spatial resolution of satellite imagery as well as fully automated algorithms capable of tracking crevasse displacements between repeat images despite considerable advances in developing fully transient three dimensional ice flow models over the past two decades both the zero stress and linear elastic fracture mechanics crevasse models have remained fundamentally unchanged over this time in the past decade however multidimensional and transient formulations of the continuum damage mechanics approach to simulating ice fracture have emerged the combination of employing damage mechanics to represent slow upstream deterioration of ice strength and fracture mechanics to represent rapid failure at downstream termini holds promise for implementation in large scale ice sheet models finally given the broad interest in the sea level rise implications of recent and future cryospheric change we provide a synthesis of 10 mechanisms by which crevasses can influence glacier mass balance

the impact of finer resolution air sea coupling on the intraseasonal oscillation of the indian monsoon abstracta newly assembled atmosphere ocean coupled model called hadkpp is described and then used to determine the effects of subdaily air sea coupling and fine near surface ocean vertical resolution on the representation of the northern hemisphere summer intraseasonal oscillation hadkpp comprises the hadley centre atmospheric model coupled to the k profile parameterization ocean boundary layer model four 30 member ensembles were performed that vary in ocean vertical resolution between 1 and 10 m and in coupling frequency between 3 and 24 h the 10 m 24 h ensemble exhibited roughly 60 of the observed 30 50 day variability in sea surface temperatures and rainfall and very weak northward propagation enhancing only the vertical resolution or only the coupling frequency produced modest improvements in variability and just a standing intraseasonal oscillation only the 1 m 3 h configuration generated organized northward propagating convection similar to observations subdaily surface forcing produced s

is there a single surge mechanism contrasts in dynamics between glacier surges in svalbard and other regions 1 during the 1990s monacobreen a 40 km long tidewater glacier in svalbard underwent a major surge we mapped the surge dynamics using ers synthetic aperture radar images differential dual azimuth interferometry and intensity correlation tracking a series of 11 three dimensional 3 d velocity maps covering the period 1991 1997 show a months long initiation and years long termination to the surge with no indication of a surge front travelling downglacier during the surge the front of the glacier advanced 2 km the velocity and derived strain rate increased by more than an order of magnitude and maximum ice flow rates measured during 1994 were 5 m d 1 the spatial pattern of both velocity and strain rate was remarkably consistent and must therefore be controlled by spatially fixed processes operating at the glacier bed we combine these results with those published in the literature to construct a typical svalbard glacier surge cycle and compare this to surge dynamics of glaciers from other cluster regions especially those of variegated glacier in alaska the strong contrast in dynamics suggests that there exist at least two distinct surge mechanisms