dynamics of surge type glaciers in west kunlun shan northwestern tibet here we examine 31 glaciers in the west kunlun shan of the northwestern tibetan plateau and identify 9 as surge type the method is based on satellite synthetic aperture radar and landsat optical images the former going back to 1992 the latter to 1972 to identify surge type glaciers we consider temporal changes in velocity changes in glacier terminus position propagation of a surge bulge presence of looped and or contoured medial moraines and extensive crevassing other than the nine surge type glaciers we identify two that have likely surged and six that may be surge type but no glacier surges more than once during the observation period meaning that the recurrence interval exceeds 42 years in addition we examine the evolution of the surface velocities at two surging glaciers with the unprecedented temporal resolution of down to 11 days over 7 years the results show clear seasonal modulations by as much as 200 in early winter against those in early summer this seasonal modulation in surface velocity suggests the presence of surface meltwater that reroutes through the englacial and subglacial drainage systems thus our findings suggest that the hydrological processes originating in the surface meltwater play an important role in maintaining the yearlong active surging phase

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

nonlinear spectral mixture modeling to estimate water ice abundance of martian regolith abstract we present a new technique to estimate the abundance of water ice in the martian permafrost using phoenix lander surface stereo imager ssi multispectral data past work estimated this abundance by employing radiative transfer methods to model the spectra of ice and regolith mixtures using the optical constants of water ice and a martian analogue soil our technique removed the uncertainty of using an analogue or of estimating a regolith composition by deriving the optical constants directly from observations of icy regolith acquired before and after sublimation of the ice at similar viewing geometries laboratory spectral measurements of known mixtures of water ice and dry soil at controlled viewing geometries allowed us to constrain the uncertainty in our technique we found that model fits across the observational uncertainty will contain the actual water ice fraction we then applied the technique to phoenix ssi observations of snow white trench and dodo goldilocks trench for the snow white trench we estimated water ice abundances consistent with pore fill in the near surface ice consistent with atmospheric diffusion for the dodo goldilocks trench we estimate water ice abundances larger than pore fill would allow these results have implications to our understanding of the history of water ice on mars and the role of the regolith at high latitudes as a reservoir of atmospheric h2o

driven by excess climatic implications of new global mapping of near surface water equivalent hydrogen on mars abstract we present improved mars odyssey neutron spectrometer mons maps of near surface water equivalent hydrogen weh on mars that have intriguing implications for the global distribution of excess ice which occurs when the mass fraction of water ice exceeds the threshold amount needed to saturate the pore volume in normal soils we have refined the crossover technique of feldman et al 2011 by using spatial deconvolution and gaussian weighting to create the first globally self consistent map of weh at low latitudes our new maps indicate that weh exceeds 15 in several near equatorial regions such as arabia terra which has important implications for the types of hydrated minerals present at low latitudes at high latitudes we demonstrate that the disparate mons and phoenix robotic arm ra observations of near surface weh can be reconciled by a three layer model incorporating dry soil over fully saturated pore ice over pure excess ice such a three layer model can also potentially explain the strong anticorrelation of subsurface ice content and ice table depth observed at high latitudes at moderate latitudes we show that the distribution of recently formed impact craters is also consistent with our latest mons results as both the shallowest ice exposing crater and deepest non ice exposing crater at each impact site are in good agreement with our predictions of near surface weh overall we find that our new mapping is consistent with the widespread presence at mid to high martian latitudes of recently deposited shallow excess ice reservoirs that are not yet in equilibrium with the atmosphere

remote sensing based analysis of the 1996 surge of northern inylchek glacier central tien shan kyrgyzstan the evolution of northern inylchek glacier and its proglacial lake upper lake merzbacher during its 1996 surge and the surrounding decades is analyzed with remote sensing imagery overall retreat of the glacier from 1943 to 1996 enlarged the lake to 4 km long and 100 m deep the surge in 1996 initiated between 12 september and 7 october and advanced the glacier by 3 7 km to override most of upper lake merzbacher the surge phase probably ended in december 1996 and involved mean flow velocities across the lower trunk of the glacier that reached 50 m d 1 over a 32 day period water displaced by the surge from upper lake merzbacher totalling 1 5 108 m3 in volume accelerated filling of lower lake merzbacher downvalley and helped trigger this marginal ice dammed lake to outburst in a jokulhlaup around late november early december the characteristics and duration of the surge render it as similar to temperate glacier surges elsewhere it may have been facilitated by low basal friction caused by water saturated sediments in the upper lake bed furthermore bathymetric measurements show that the surge evacuated much sediment into the upper lake causing its depth to reduce from 20 to 30 m in 1996 to 8 m by 2005 and 2 m by 2011 the corresponding deposition rates imply glacier catchment specific mean sediment yields of 1 4 to 3 4 103 mg km 2 a 1 in the years after the surge our study documents novel interactions within a cascade system of glaciers and lakes that exhibits surging and outburst flood behavior

early twenty first century glacier mass losses in the indus basin constrained by density assumptions abstract glaciers in the upper indus supply more than half of the river water are experiencing significant melting with a debated fate the recent melting rate is still contained by considerable uncertainties hindering to estimate precise glacier mass change here we present geodetic mass balance results for the whole indus basin using srtm and alos 30 m elevation data improved glacier inventory optimized glacier surface density and validation through in situ differential gps and icesat data our glacier inventory and derived by improving rgi6 0 boundaries and separated into debris cover and debris free parts the derived surface elevation changes were converted into annual mass balances using separated density assumptions four criteria for debris covered ice 900 60 kg m 3 debris free ice below 20 and 25 slopes 850 60 kg m 3 and above 20 and 25 slopes 600 60 kg m 3 respectively the resulting mass balance biased between 0 20 and 0 09 m water equivalent w e a 1 using an average 850 60 kg m 3 density assumption throughout the indus basin in the western himalaya and hindu kush the glacier mass losses are less affected by the average density assumption compared to the karakoram the western hunza and central shigar karakoram glaciers show negligible mass losses of 0 02 0 12 and 0 01 0 13 m w e a 1 in contrast to the relatively more negative mass balance 0 26 0 21 m w e a 1 in the eastern shyok karakoram all the sub basins exhibit negative mass balances with the most negative values ranging from 0 34 0 31 to 0 44 0 27 m w e a 1 in the ravi chenab and jhelum sub basins of the himalaya the whole indus basin contributes approximately 0 014 0 016 mm a 1 to the global mean sea level equivalent

modeling the development of martian sublimation thermokarst landforms abstract sublimation thermokarst landforms result from collapse of the surface when ice is lost from the subsurface on mars scalloped landforms with scales of decameters to kilometers are observed in the mid latitudes and considered likely thermokarst features we describe a landscape evolution model that couples diffusive mass movement and subsurface ice loss due to sublimation over periods of tens of thousands of mars years under conditions similar to the present the model produces scallop like features similar to those on the martian surface starting from much smaller initial disturbances the model also indicates crater expansion when impacts occur in surfaces underlain by excess ice to some depth with morphologies similar to observed landforms on the martian northern plains in order to produce these landforms by sublimation substantial quantities of excess ice are required at least comparable to the vertical extent of the landform and such ice must remain in adjacent terrain to support the non deflated surface we suggest that martian thermokarst features are consistent with formation by sublimation without melting and that significant thicknesses of very clean excess ice up to many tens of meters the depth of some scalloped depressions are locally present in the martian mid latitudes climate conditions leading to melting at significant depth are not required

geomorphological evidence of localized stagnant ice deposits in terra cimmeria mars the presence of snow and ice at mid latitudes of mars cannot be explained by current climatic conditions as surface ice is unstable however a large variety of debris covered glaciers have been observed at both mid latitudes here we report the presence of local small scale and debris covered stagnant ice deposits on the floor of a valley system in terra cimmeria these deposits termed valley fill deposits vfd have a distribution that is restricted to the host valley floor and to the extent of the ejecta blanket associated with tarq impact crater the vfd are characterized by convex upward morphology various crevasses sublimation pits an average area of a few km2 and occasional ejecta streaks on their surface our model age estimation points to two possible time frames for the tarq impact event thus we suggest two formation scenarios for vfd i distribution of ice due to impact into shallow ice during the middle amazonian ii post impact deposition of vfd due to precipitation in both scenarios ice preservation is most likely due to a lag of dust and debris deposited in the valley s topographic lows scenario i is more consistent with our geomorphological observation of the vfd being overlain by ejecta streaks our results highlight the importance of local geological events and conditions in the distribution and preservation of buried ice deposits on mars and suggest that more small scale and debris covered ice deposits may exist in the mid latitudes than previously thought these deposits are of high importance for future human exploration missions to mars

results from the mars phoenix lander robotic arm experiment 1 the mars phoenix lander was equipped with a 2 4 m robotic arm ra with an icy soil acquisition device capable of excavating trenches in soil deposits grooming hard icy soil surfaces with a scraper blade and acquiring icy soil samples using a rasp tool a camera capable of imaging the scoop interior and a thermal and electrical conductivity probe were also included on the ra a dozen trench complexes were excavated at the northern plains landing site and 31 samples including water ice bearing soils were acquired for delivery to instruments on the lander during the 152 sol mission deliveries included sprinkling material from several centimeters height to break up cloddy soils on impact with instrument portals excavations were done on the side of the humpty dumpty and the top of the wonderland polygons and in nearby troughs resistive forces encountered during backhoe operations show that soils above the 3 5 cm deep icy soil interfaces are stronger with increasing depth further soils are similar in appearance and properties to the weakly cohesive crusty and cloddy soils imaged and excavated by the viking lander 2 which also landed on the northern plains adsorbed h2o is inferred to be responsible for the variable nature and cohesive strength of the soils backhoe blade chatter marks on excavated icy soil surfaces combined with rasp motor currents are consistent with laboratory experiments using grain supported icy soil deposits as is the relatively rapid decrease in icy soil strength over time as the ice sublimated on mars

warming and wetting climate during last century revealed by an ice core in northwest tibetan plateau glaciers on the tibetan plateau tp exist in different states of extension and retreat responding to the westerly winds and indian monsoon however few studies to date have focused on climate change in the westerlies dominated northwest tp here we report an ice core climate record during the last century retrieved from the kuokuosele kksl glacier in the westerlies dominated eastern pamir northwest tp the ice core has dated based on annual layer counting using ice core delta o 18 seasonal cycles constrained by both the beta beta activity peak and cs 137 concentration peak in 1962 63 reconstruction of delta o 18 and annual accumulation from the ice core and comparison with observed temperature and precipitation at nearby meteorological stations as well as cru climate research unit data confirm their climatic and regional significance both ice core delta o 18 and accumulation increased during the last century thus pointing to a warming and wetting trend in the westerlies dominated northwest tp

phoenix soil physical properties investigation 1 the phoenix lander investigated the polygonal terrain and associated soil and icy soil deposits of a high northern latitude site on mars the soil physical properties component involved the analysis of force data determined from motor currents from the robotic arm ra s trenching activity using this information and images of the landing site soil cohesion and angle of internal friction were determined dump pile slopes were used to determine the angle of internal friction of the soil 38 5 additionally an excavation model that treated walls and edges of the scoop as retaining walls was used to calculate mean soil cohesions for several trenches in the phoenix landing site workspace these cohesions were found to be consistent with the stability of steep trench slopes cohesions varied from 0 2 0 4kpa to 1 2 1 8 kpa with the exception of a subsurface platy horizon unique to a shallow trough for which cohesion will have to be determined using other methods soil on polygon mounds had the greatest cohesion 1 2 1 8 kpa this was most likely due to the presence of adsorbed water or pore ice above the shallow icy soil surface further evidence for enhanced cohesion above the ice table includes lateral increase in excavation force by over 30 n as the ra approached ice

mass balance and a glacier surge of guliya ice cap in the western kunlun shan between 2005 and 2015 abstract contemporary estimates of glacier changes are necessary to assess the impact of climate change associated hazards and water resources management glaciers in high mountain asia hma are mostly retreating except the karakoram and western kunlun shan confirmed by remote sensing measurements however ground validation with precise measurements of these mass balance estimates are scarce this study selected guliya ice cap in the western kunlun shan to observe its recent changes regarding surface dynamics and mass balance using aster dem of 2005 and 2015 our findings indicate that one of the north facing glaciers surged with no previous surging history during july and early november 2015 advancing at about 8 m per day on average the mass balance shows a balance condition 0 01 0 02 m w e a 1 the icesat data 2004 2008 at selected locations compared to dgps data collected in the field during 2015 indicating a minute difference of 0 03 0 05 m a 1 with aster data in the same area our findings suggest that guliya ice cap in the western kunlun shan is in equilibrium state following a similar pattern mass gain or stable conditions as observed previously

the january 2018 to september 2019 surge of shisper glacier pakistan detected from remote sensing observations abstract this study analysed the actively surging shisper glacier in the karakoram region of pakistan using earth observation data from landsat 8 oli and planet images changes in the surface glacier velocity supraglacial moraines and debris cover were assessed using landsat 8 data at monthly time steps from january 2018 to may 2019 high resolution data from planet labs was used to precisely detect the snout advance and ice dammed lake expansion downstream cross section profiles of the valley were generated using a moderate resolution digital elevation model to assess the inundation in the event of rapid ice dammed lake drainage correlation image analysis software working on the principle of normalized cross correlation was used to generate time series monthly surface velocity profiles for shisper glacier manual digitization at 1 30000 scale was used to delineate supraglacial moraines and supraglacial debris cover the glacier surface velocity profiles indicate that the ablation zone of the glacier continues to be in an active surge phase resulting in advance of the snout and expansion of the ice dammed lake surface glacier velocities are as high as 48 m d 1 between 18 december 2018 and 8 may 2019 the glacier snout advanced at 6 m d 1 with a total overall advance of 860 m the lake formed due to damming of an outflow stream from mochowar glacier expanded to its maximum area 29 69 ha in may 2019 before drainage started on 23 june 2019 our estimates indicate that the peak discharge in case of rapid drainage could vary between 5033 m3 s 1 and 6167 m3 s 1 and potentially affect infrastructure downstream

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

on the orbital forcing of martian water and co2 cycles a general circulation model study with simplified volatile schemes 1 variations in the martian water and co2 cycles with changes in orbital and rotational parameters are examined using the geophysical fluid dynamics laboratory mars general circulation model the model allows for arbitrary specification of obliquity eccentricity and argument of perihelion as well as the position and thickness of surface ice exchange of co2 between the surface and atmosphere is modeled generating seasonal cycles of surface ice and surface pressure water is allowed to exchange between the surface and atmosphere cloud formation is treated and both cloud and vapor are transported by modeled winds and diffusion exchange of water and co2 with the subsurface is not allowed and radiative effects of water vapor and clouds are not treated the seasonal cycle of co2 is found to become more extreme at high obliquity as suggested by simple heat balance models maximum pressures remain largely the same but the minima decrease substantially as more co2 condenses in the more extensive polar night vapor and cloud abundances increase dramatically with obliquity the stable location for surface ice moves equatorward with increasing obliquity such that by 45 obliquity water ice is stable in the tropics only ice is not spatially uniform but rather found preferentially in regions of high thermal inertia or high topography eccentricity and argument of perihelion can provide a second order modification to the distribution of surface ice by altering the temporal distribution of insolation at the poles further model simulations reveal the robustness of these distributions for a variety of initial conditions our findings shed light on the nature of near surface ice rich deposits at midlatitudes and low latitudes on mars

massive collapse of two glaciers in western tibet in 2016 after surge like instability surges and glacier avalanches are expressions of glacier instability and among the most dramatic phenomena in the mountain cryosphere until now the catastrophic collapse of a glacier combining the large volume of surges and mobility of ice avalanches has been reported only for the 2002 130 106 m3 detachment of kolka glacier caucasus mountains which has been considered a globally singular event here we report on the similar detachment of the entire lower parts of two adjacent glaciers in western tibet in july and september 2016 leading to an unprecedented pair of giant low angle ice avalanches with volumes of 68 2 106 m3 and 83 2 106 m3 on the basis of satellite remote sensing numerical modelling and field investigations we find that the twin collapses were caused by climate and weather driven external forcing acting on specific polythermal and soft bed glacier properties these factors converged to produce surge like enhancement of driving stresses and massively reduced basal friction connected to subglacial water and fine grained bed lithology to eventually exceed collapse thresholds in resisting forces of the tongues frozen to their bed our findings show that large catastrophic instabilities of low angle glaciers can happen under rare circumstances without historical precedent two catastrophic glacier collapse events in western tibet in 2016 were caused by a convergence of weather and glacier bed conditions according to an analysis of observations and modelling

glacier changes in the west kunlun shan from 1970 to 2001 derived from landsat tm etm and chinese glacier inventory data

changes in glacier extent and surface elevations in the depuchangdake region of northwestern tibet china abstract remote sensing data including those from landsat thematic mapper enhanced thematic mapper plus tm etm the shuttle radar topography mission digital elevation model srtm4 1 dem and the geoscience laser altimeter system ice cloud and land elevation satellite glas icesat show that from 1991 to 2013 the glacier area in the depuchangdake region of northwestern tibet decreased from 409 to 393 km 2 an overall loss of 16 km 2 or 3 9 of the entire 1991 glacial area the mean glacier thinning rate was 0 40 0 16 m equivalent height of water per year w e yr equating to a glacier mass balance of 0 16 0 07 km 3 w e yr total mass loss from 2003 to 2009 was 1 13 0 46 km 3 glacier retreat likely reflects increases in annual total radiation annual positive degree days and maximum temperature with concurrent increases in precipitation insufficient to replenish glacial mass loss the rate of glacier retreat in depuchangdake is less than that for himalayan glaciers in indian monsoon dominated areas but greater than that for karakoram glaciers in mid latitude westerly dominated areas glacier type climate zone and climate change all impact on the differing degrees of long term regional glacial change rate however special glacier distribution forms can sometimes lead to exceptional circumstances

concentrated perchlorate at the mars phoenix landing site evidence for thin film liquid water on mars 1 nasa s phoenix mission which landed on the northern plains of mars in 2008 returned evidence of the perchlorate anion distributed evenly throughout the soil column at the landing site here we use spectral data from phoenix s surface stereo imager to map the distribution of perchlorate salts at the phoenix landing site and find that perchlorate salt has been locally concentrated into subsurface patches similar to salt patches that result from aqueous dissolution and redistribution on earth we propose that thin films of liquid water are responsible for translocating perchlorate from the surface to the subsurface and for concentrating it in patches the thin films are interpreted to result from melting of minor ice covers related to seasonal and long term obliquity cycles

vertical distribution of dust and water ice aerosols from crism limb geometry observations 1 near infrared spectra taken in a limb viewing geometry by the compact reconnaissance imaging spectrometer for mars crism on board the mars reconnaissance orbiter provide a useful tool for probing atmospheric structure specifically the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved more than a dozen sets of crism limb observations have been taken so far providing pole to pole cross sections spanning more than a full martian year radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well mixed or conrath v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season dust typically extends to higher altitudes 40 50 km during the perihelion season than during the aphelion season 20 km and the hellas region consistently shows more dust mixed to higher altitudes than other locations detached water ice clouds are common and water ice aerosols are observed to cap the dust layer in all seasons

hirise observations of new impact craters exposing martian ground ice twenty small new impact craters or clusters have been observed to excavate bright material inferred to be ice at mid latitudes and high latitudes on mars in the northern hemisphere the craters are widely distributed geographically and occur at latitudes as low as 39 n stability modeling suggests that this ice distribution requires a long term average atmospheric water vapor content around 25 precipitable micrometers more than double the present value which is consistent with the expected effect of recent orbital variations alternatively near surface humidity could be higher than expected for current column abundances if water vapor is not well mixed with atmospheric co2 or the vapor pressure at the ice table could be lower due to salts ice in and around the craters remains visibly bright for months to years indicating that it is clean ice rather than ice cemented regolith although some clean ice may be produced by the impact process it is likely that the original ground ice was excess ice exceeding dry soil pore space in many cases observations of the craters suggest small scale heterogeneities in this excess ice the origin of such ice is uncertain ice lens formation by migration of thin films of liquid is most consistent with local heterogeneity in ice content and common surface boulders but in some cases nearby thermokarst landforms suggest large amounts of excess ice that may be best explained by a degraded ice sheet

history and anatomy of subsurface ice on mars abstract ice buried beneath a thin layer of soil has been revealed by neutron spectroscopy and explored by the phoenix mars lander it has also been exposed by recent impacts this subsurface ice is thought to lose and gain volume in response to orbital variations milankovitch cycles we use a powerful numerical model to follow the growth and retreat of near surface ice as a result of regolith atmosphere exchange continuously over millions of years if a thick layer of almost pure ice has been deposited recently it has not yet reached equilibrium with the atmospheric water vapor and may still remain as far equatorward as 43 n where ice has been revealed by recent impacts a potentially observable consequence is present day humidity output from the still retreating ice we also demonstrate that in a sublimation environment subsurface pore ice can accumulate in two ways the first mode widely known is the progressive filling of pores by ice over a range of depths the second mode occurs on top of an already impermeable ice layer subsequent ice accumulates in the form of pasted on horizontal layers such that beneath the ice table the pores are completely full with ice most or all of the pore ice on mars today may be of the second type at the phoenix landing site where such a layer is also expected to exist above an underlying ice sheet it may be extremely thin due to exceptionally small variations in ice stability over time

mars global atmospheric oscillations annually synchronized transient normal mode oscillations and the triggering of global dust storms observation and analyses of the atmospheric pressure at the surface on mars for several martian years has led to the discovery of transient events in the daily pressure variations of an unusual nature these events last only a few sols mars days appear to repeat on an annual basis to within a few sols appear to cover a large portion of the hemisphere on the same sol or at least within a few sols occur in pairs with separations of 20 sols in some instances are coincident with the annual pressure minimum i e the maximum concentration of carbon dioxide in the southern hemisphere and consist of spectral components near to and sometimes identical in frequency to the diurnal and semidiurnal harmonics it is suggested that these events are kelvin normal mode transient global oscillations examination of the initiation of the 1977a 1977b and 1982a global dust storms indicate that pseudo diurnal and some times pseudo semidiurnal oscillations exist during the initiation phase and might be involved in triggering the global dust storms possibly in conjunction with winds due to longer period circulations the diurnal harmonic disappears prior to the 1977b global dust storm and is replaced by an oscillation at 1 1 cycles sol if the lack of a classical diurnal tide indicates the suppression of convection this might partially explain the slow growth of the 1977b storm the daily average pressure during the transient season which precedes the global dust storm season by almost one fourth of a year exhibits a different behavior during the global dust storm years than during the nonglobal dust storm years this implies that the global circulation must differ significantly in these cases and may be related to the presence or absence of global dust storms later in a given year these analyses suggest that an almost diurnal and an almost semidiurnal high frequency global oscillation different from the classical solar driven tides may be quite common on mars

the kolka karmadon rock ice slide of 20 september 2002 an extraordinary event of historical dimensions in north ossetia russian caucasus on 20 september 2002 an enormous rock ice slide and subsequent mud flow occurred on the northern slope of the kazbek massif northern ossetia russian caucasus it started on the north northeast wall of dzhimarai khokh 4780 ma s l and seriously affected the valley of genaldon karmadon immediate governmental actions available scientific information first reconstructions hazard assessments and monitoring activities as well as initial expert judgments recommendations are documented in order to enable more detailed analyses and modelling of the event by the wider scientific community among the most remarkable aspects related to this event are 1 the relation between the recent event and somewhat smaller but quite similar events that occurred earlier in historical times 1835 1902 2 the interactions between unstable local geological structures and complex geothermal and hydraulic conditions in the starting zone with permafrost cold to polythermal hanging glaciers and volcanic effects hot springs in close contact with each other 3 the erosion and incorporation of a debris covered valley glacier largely enhancing the sliding volume of rocks ice firn snow water and probably air to a total of about 100 106m3 and 4 the astonishingly high flow velocities up to 300 km h 1 and enormous length of travel path 18 km plus 15 km of debris mud flow this extraordinary case illustrates that large catastrophic events in high mountain regions typically involve a multitude of factors and require integrated consideration of complex chains of processes a task which must be undertaken by qualified groups of experts

numerical modeling of a gravity driven instability of a cold hanging glacier reanalysis of the 1895 break off of altelsgletscher switzerland

crater morphology and evolution at the phoenix landing site insights into timing of modern geological processes and subsurface ice abstract we report results of an in depth study of the morphology of small km scale and smaller craters over a 4000 km2 region on mars that includes the phoenix landing ellipse focused on the nature and timing of geological processes that have been active in the region the study seeks to constrain regolith depositional rates thickness of ground ice layer abundance of ice in the subsurface and the rate of crater degradation measurements of the size of ejecta blocks around craters show that the region has not been a net depositional site over the last billion years most craters smaller than 200 350 m lack ejecta blocks regardless of age indicating that there is a layer approximately 20 35 m deep that either does not form or does not retain ejecta blocks this layer is expressed both within and outside the extended ejecta blanket of heimdal crater implying that it is not associated with the ejecta blanket we propose that this unconsolidated layer consists dominantly of ice cemented soil which raises questions about the emplacement of ice at depth we also note clear progression in crater degradation morphology which allows us to place constraints on the rate and style of crater degradation small craters 20 to 200 m in diameter appear to lose their relief due to slow infilling of the bowl over time scales of 5 100 kyr the infilling of small craters perhaps by a combination of ice and dust presents a mechanism by which ice is buried down to a few tens of meters on the other hand larger craters 200 m to 1 km do not exhibit evidence for infilling but do exhibit concentric sets of fractures within and outside the rim we propose that loss of relief of the larger craters is due to viscous creep over time scales of a few to tens of myr this latter interpretation would require the presence of water ice in abundances greater than pore filling down to depths of at least tens of meters

slight mass gain of karakoram glaciers in the early twenty first century the mass balance of hindu kush karakoram himalaya glaciers has been debated partly because of a severe lack of observations from the region an analysis of the regional mass balance of karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area

compositions of subsurface ices at the mars phoenix landing site 1 nasa s phoenix lander uncovered two types of ice at its 2008 landing site on the northern plains of mars a brighter slab like ice that broke during robotic arm operations and a darker icy deposit spectra from the phoenix surface stereo imager ssi are used to demonstrate that the brighter material consists of nearly pure water ice which probably formed by migration and freezing of liquid water the darker icy material consists of 30 20 wt ice with the remainder composed of fine grained soil indicating that it probably formed as pore ice these two types of ice represent two different emplacement mechanisms and periods of deposition

lake water and glacier mass gains in the northwestern tibetan plateau observed from multi sensor remote sensing data implication of an enhanced hydrological cycle abstract lakes and glaciers are widely distributed in the northwestern tibetan plateau a synchronized examination of lake and glacier mass variations there has not previously been conducted which has limited the understanding of the lake water balance and the hydrologic cycle in the region in this study we comprehensively examine lake area and volume and glacier mass changes using multi sensor satellite data we find that lake expansion in the northwestern tibetan plateau was more robust from 1976 to 2018 when compared to other regions of the plateau especially for the glacier fed and endorheic lakes lake volume changes show that most of the lakes had an increase in water volume particularly in 2000 2018 with a total water storage gain of 28 6 gt by using high resolution kh 9 and tandem x data we observe that the glacier surface elevation of the western kunlun mountains had a slight thinning rate of 0 07 0 16 m yr in 1973 2000 but a positive rate of 0 002 0 003 m yr in 2000 2018 the heterogeneous pattern of glacier elevation changes between the north n and south s slopes are revealed i e 0 02 0 01 m yr n against 0 12 0 03 m yr s in 1973 2000 and 0 05 0 02 m yr n against 0 06 0 02 m yr s in 2000 2018 overall the glaciers trend to a stable state 0 05 m yr in both the south slope of the western kunlun mountains and aru co regions between 2000 and 2018 similar patterns are also found for basin wide examinations of lake storage changes mass gains and glacier mass budgets positive or close to stable the seasonal snow cover area changes derived from cloud free modis snow cover products present a variable and insignificant trend between 2003 and 2017 snow depth derived from passive microwave remote sensing data exhibits a decreasing trend between 1979 and 2015 but the water equivalent could contribute only an insignificant amount to the observed lake changes the lake water gains and almost positive glacier mass balance imply that the hydrological cycle in the northwestern tibetan plateau has become enhanced

microscopy analysis of soils at the phoenix landing site mars classification of soil particles and description of their optical and magnetic properties the optical microscope onboard the phoenix spacecraft has returned color images 4 m pixel 1 of soils that were delivered to and held on various substrates a preliminary taxonomy of phoenix soil particles based on color size and shape identifies the following particle types generic names in brackets 1 reddish fines mostly unresolved that are spectrally similar to though slightly darker than global airborne dust red fines 2 silt to sand sized brownish grains brown sand 3 silt to sand sized black grains black sand and 4 small amounts of whitish fines possibly salts white fines most particles have a saturation magnetization in the range 0 5 2 am2 kg 1 as inferred from their interaction with magnetic substrates the particle size distribution has two distinct peaks below 10 m fines and in the range 20 100 m grains respectively and is different from that of ripple soils in gusev crater in particular medium to large sand grains appear to be absent in phoenix soils most sand grains have subrounded shape with variable texture a fractured grain observed on sol 112 reveals evidence of micrometer sized crystal facets the brown sand category displays a large diversity in color including shiny almost colorless particles potential source regions for these grains may be the tharsis volcanoes or heimdal crater 20 km east of the landing site the black grains are suggested to belong to a more widespread population of particles with mafic mineralogy the absence of black brown composite grains is consistent with different formation pathways and source regions for each grain type

ground ice at the phoenix landing site stability state and origin 1 a primary objective of the phoenix mission was to examine the characteristics of high latitude ground ice on mars we report observations of ground ice its depth distribution and stability characteristics and examine its origins and history high latitude ground ice was explored through a dozen trench complexes and landing thruster pits over a range of polygon morphological provinces shallow ground ice was found to be abundant under a layer of relatively loose ice free soil with a mean depth of 4 6 cm which varied by more than 10x from trench to trench these variations can be attributed mainly to slope effects and thermal inertia variations in the overburden soil affecting ground temperatures the presence of ice at this depth is consistent with vapor diffusive equilibrium with respect to a mean atmospheric water content of 3 4 1019 m 3 consistent with the present day climate significant ice heterogeneity was observed with two major forms ice cemented soil and relatively pure light toned ice ice cemented soils which comprised about 90 of the icy material exposed by trenching are best explained as vapor deposited pore ice in a matrix supported porous soil light toned ice deposits represent a minority of the subsurface and are thought to consist of relatively thin near surface deposits the origin of these relatively pure ice deposits appears most consistent with the formation of excess ice by soil ice segregation such as would occur by thin film migration and the formation of ice lenses needle ice or similar ice structures

the presence and stability of ground ice in the southern hemisphere of mars abstract we calculate new estimates of ground ice stability and the depth distribution of the ice table the depth boundary between ice free soil above and ice cemented soil below and compare these theoretical estimates of the distribution of ground ice with the observed distribution of leakage neutrons measured by the neutron spectrometer instrument of the mars odyssey spacecraft s gamma ray spectrometer instrument suite our calculated ground ice distribution contains improvements over previous work in that we include the effects of the high thermal conductivity of ice cemented soil at and below the ice table we include the surface elevation dependence of the near surface atmospheric humidity and we utilize new high resolution maps of thermal inertia albedo and elevation from mars global surveyor observations results indicate that ground ice should be about 5 times shallower than in previous predictions while results are dependent on the atmospheric humidity depths are generally between a few millimeters and a few meters with typical values of a few centimeters results are also geographically similar to previous predictions with differences due to the higher resolution of thermal inertia and the inclusion of elevation effects on humidity comparison with the measured epithermal neutron count rates in the southern hemisphere indicate that the geographic distribution of the count rate is best correlated with ground ice in equilibrium with 10 to 20 pr m precipitable micrometers column abundance of atmospheric water assuming a uniform distribution with co2 however given the uncertainties 5 to 30 pr m also may be viable this water abundance represents a longer term average over 100 to 1000 yr there is a high degree of correlation between the depth of the ice table and the epithermal count rate that agrees remarkably well with predicted count rates as a function of ice table depth these results indicate that ground ice in the upper meter of the martian soil is in diffusive equilibrium with the atmosphere since ground ice in this depth zone is expected to undergo saturation desiccation cycles with orbital variations this ice should be younger than about 500 kyr and was emplaced under similar cold and dry climate conditions of today remaining differences between the predicted depths of the ice table and those inferred from the neutron data are likely to be due to subpixel heterogeneity in the martian surface including the presence of rocks slopes and patches of soil with varying thermophysical properties

accelerated glacier mass loss 2011 2016 over the puruogangri ice field in the inner tibetan plateau revealed by bistatic insar measurements abstract the temporal variation of glacier mass balance during recent years remains poorly known for the mountain glaciers in the inner tibetan plateau itp due to the lack of field measurements in this study we retrieved the annual glacier mass balance of the puruogangri ice field which is the largest modern ice mass in the itp by differencing multi temporal digital elevation models dems generated with five pairs of tandem x bistatic interferometric synthetic aperture radar insar images acquired between april 2011 and january 2016 we compared the tandem x dems in january and april 2012 to estimate the x band radar penetration depth difference 0 61 0 06 m which enabled systematic bias correction in the estimation of annual glacier mass balance the observed mass balance reveals a glacier mass gain of 0 44 0 10 m w e yr 1 in 2011 12 which was followed by accelerated glacier mass loss in 2012 16 glacier mass balances of 0 13 0 03 0 34 0 06 and 0 52 0 10 m w e yr 1 were estimated for the periods of 2012 13 2013 14 and 2014 16 respectively this accelerating trend of glacier mass loss is likely caused by the continuous decrease in annual precipitation according to the climate data recorded by adjacent meteorological stations this study demonstrates that repeated bistatic insar measurement is a promising method for monitoring glacier elevation change and mass balance at regular intervals

high spatial and temporal resolution sampling of martian gas abundances from crism spectra 1 the compact reconnaissance imaging spectrometer for mars on the mars reconnaissance orbiter spacecraft has been collecting spectra in the visible to near infrared wavelength range for over 5 years approximately 3 martian years observations consist of image cubes with two main selections of spectral sampling 74 and 545 spectral channels and two main selections of spatial sampling approximately 20 and 200 m pixel retrievals of gas abundances specifically co2 h2o and co are performed from spectra collected in all observation modes the retrievals are efficiently performed using a look up table where the strength of gas absorption features are precalculated for an n dimensional discrete grid of known input parameters season location environment viewing geometry etc and the one unknown parameter to be retrieved gas abundance a reverse interpolation in the look up table is used to match the observed strength of the gas absorption to the gas abundance this algorithm is extremely fast compared to traditional radiative transfer computations that seek to recursively fit calculated results to an observed spectral feature and can therefore be applied on a pixel by pixel basis to the tens of thousands of compact reconnaissance imaging spectrometer for mars images to examine cross scene structure as well as to produce climatological averages