high resolution sar interferometry estimation of local frequencies in the context of alpine glaciers synthetic aperture radar sar interferometric data offer the opportunity to measure temperate glacier surface topography and displacement the increase of the resolution provided by the most recent sar systems has some critical implications for instance a reliable estimate of the phase gradient can only be achieved by using interferogram local frequencies in this paper an original two step method for estimating local frequencies is proposed the 2 d phase signal is considered to have two deterministic components corresponding to low resolution lr fringes and high resolution hr patterns due to the local microrelief respectively the first step of the proposed algorithm consists in the lr phase flattening in the second step the local hr frequencies are estimated from the phase 2 d autocorrelation function computed on adaptive neighborhoods this neighborhood is the set of connected pixels belonging to the same hr spatial feature and respecting the ldquolocal stationarityrdquo hypothesis results with both simulated terrasar x interferograms and real airborne e sar images are presented to illustrate the potential of the proposed method

combining airborne photographs and spaceborne sar data to monitor temperate glaciers potentials and limits monitoring temperate glacier activity has become more and more necessary for economical and security reasons and as an indicator of the local effects of global climate change remote sensing data provide useful information on such complex geophysical objects but they require specific processing techniques to cope with the difficult context of moving and changing features in high relief areas this paper presents the first results of a project involving four laboratories developing and combining specific methods to extract information from optical and synthetic aperture radar sar data two different information sources are processed namely 1 airborne photography and 2 spaceborne c band sar interferometry the difficulties and limitations of their processing in the context of alpine glaciers are discussed and illustrated on two glaciers located in the mont blanc area the results obtained by aerial triangulation techniques provide digital terrain models with an accuracy that is better than 30 cm which is compatible with the computation of volume balance and useful for precise georeferencing and slope measurement updating the results obtained by sar differential interferometry using european remote sensing satellite images show that it is possible to measure temperate glacier surface velocity fields from october to april in one day interferograms with approximately 20 m ground sampling this allows to derive ice surface strain rate fields required to model the glacier flow these different measurements are complementary to results obtained during the summer from satellite optical data and ground measurements that are available only in few accessible points

modification of the dichotomy boundary on mars by amazonian mid latitude regional glaciation 1 restoration of the dichotomy boundary to its original position to assess its origin requires a thorough knowledge of processes responsible for its degradation and retreat the unique fretted terrain located along the deuteronilus protonilus mensae northern mid latitude portion of the boundary has been long held to provide clues to dichotomy degradation processes we use new spacecraft data to show that fretted valleys display a multitude of characteristics typical of integrated valley glacial systems on earth multiple theater headed alcove like accumulation areas sharp arete like ridges typical of glacial erosion converging patterns of downslope valley flow valley lineation patterns typical of folding and shear wrap around features indicative of flow around obstacles and broad piedmont like lobes as the valley fill extends out into the northern lowlands the single integrated system containing these features covers about 30 000 km2 and is one of dozens of fretted valleys along the dichotomy boundary in this region these relationships suggest that the boundary area was subjected to very large scale regional glaciation during the amazonian recognition and documentation of this important late stage process provides information critical to reconstructing the original dichotomy boundary

ice and debris in the fretted terrain mars viking moderate and high resolution images along the northern highland margin were studied monoscopically and stereoscopically to contribute to an understanding of the development of fretted terrain results suport the hypothesis that the fretting process involved flow facilitated by interstitial ice the process apparently continued for a long period of time and debris apron formation shaped the fretted terrain in the past as well as the present interstitial ice in debris aprons is most likely derived from ground ice obtained by sapping or scarp collapse debris aprons could have been removed by sublimation if they consisted mostly of ice or by deflation if they consisted mostly of debris to remove the debris wind erosion was either very intense early in martian history or was intermittent perhaps owing to climatic cycles the location of debris aprons in two midlatitudinal belts can be attributed to atmospheric conditions that permit ice to remain in the ground at moderate depth in those latitudes and climatic factors that permit temperatures to be warm enough for ice to flow channels have minimum gradients of 5 8 m km which permits flowing ice to deform by dislocation creep at exceedingly low strain rates alternately ice charged debris may have been buoyed by brines by analogy with the fretted channels ice could have flowed through the outflow channels if the atmospheric pressure was somewhat higher in the past and permitted ice to exist in the equatorial area

volatile fluxes through the big bend section of the san andreas fault california helium and carbon dioxide systematics abstract to investigate the source of volatiles and their relationship to the san andreas fault system safs 18 groundwater samples were collected from wells near the big bend section of the safs in southern california and analyzed for helium and carbon abundance and isotopes concentrations of 4 he corrected for air bubble entrainment vary from 4 15 to 62 7 10 8 cm 3 stp g 1 h 2 o 3 he 4 he ratios vary from 0 09 to 3 52 r a where r a air 3 he 4 he consistent with up to 44 mantle helium in samples a subset of 10 samples was analyzed for the major volatile phase co 2 the hypothesized carrier phase of the helium in the mantle crust system co 2 3 he ratios vary from 0 614 to 142 10 11 and 13 c co 2 values vary from 21 5 to 11 9 vs pdb 3 he 4 he ratios and co 2 concentrations are highest in the wells located in the mil potrero and cuddy valleys adjacent to the safs the elevated 3 he 4 he ratios are interpreted to be a consequence of a mantle volatile flux though the safs diluted by radiogenic he produced in the crust samples with the highest 3 he 4 he ratios also had the lowest co 2 3 he ratios the combined helium isotope he co 2 elemental relationships and 13 c co 2 values of the groundwater volatiles reveal a mixture of mantle and deep crustal metamorphic fluid origins the flux of fluids into the seismogenic zone at high hydrostatic pressure may cause fault rupture and transfer volatiles into the shallow crust we calculate an upward fluid flow rate of 147 mm a 1 along the safs up to 37 times higher than previous estimates kennedy et al 1997 however using newly identified characteristics of the safs we calculate a total flux of 3 he along the safs of 7 4 10 3 cm 3 stp a 1 0 33 mol 3 he a 1 and a co 2 flux of 1 5 10 13 cm 3 stp a 1 6 6 10 8 mol a 1 1 of previous estimates lower fluxes along the big bend section of the safs suggest that the flux of mantle volatiles alone is insufficient to cause the super hydrostatic pressure in the seismogenic zone however results identify crustal metamorphic fluids as a major component of the co 2 volatile budget which may represent the additional flux necessary for fault weakening pressure in the safs

satellite radar interferometry for monitoring ice sheet motion application to an antarctic ice stream satellite radar interferometry sri provides a sensitive means of monitoring the flow velocities and grounding line positions of ice streams which are indicators of response of the ice sheets to climatic change or internal instability the detection limit is about 1 5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction the grounding line detected by tidal motions where the ice goes afloat can be mapped at a resolution of 0 5 kilometer the sri velocities and grounding line of the rutford ice stream antarctica agree fairly well with earlier ground based data the combined use of sri and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

mars global surveyor observations of martian fretted terrain the martian fretted terrain between latitudes 30 and 50 n and between 315 and 360 w has been reexamined in light of new mars orbiter camera moc and mars orbiter laser altimeter mola data from mars global surveyor much of the terrain in the 30 50 latitude belt in both hemispheres has a characteristic stippled or pitted texture at moc 1 5 m scale the texture appears to result from partial removal of a formerly smooth thin deposit as a result of sublimation and deflation a complex history of deposition and exhumation is indicated by remnants of a former thicker cover of layered deposits in some hollows and on some slopes particularly those facing the pole are smooth textured deposits outlined by an outward facing escarpment throughout the study area are numerous escarpments with debris flows at their base the escarpments typically have slopes in the 20 30 range at the base of the escarpment is commonly a deposit with striae oriented at right angles to the escarpment outside this deposit is the main debris apron with a surface that typically slopes 2 3 and complex surface textures suggestive of compression sublimation and deflation the presence of undeformed impact craters indicates that the debris flows are no longer forming fretted valleys contain lineated fill and are poorly graded they likely form from fluvial valleys that were initially like those elsewhere on the planet but were subsequently widened and filled by the same mass wasting processes that formed the debris aprons slope reversals indicate that downvalley flow of the lineated fill is minor the ubiquitous presence of breaks in slope formed by mass wasting and the complex surface textures that result from mass wasting deflation and sublimation decreases the recognizability of the shorelines formerly proposed for this area

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

measurement of ice sheet topography using satellite radar interferometry detailed digital elevation models dems do not exist for much of the greenland and antarctic ice sheets radar altimetry is at present the primary in many cases the only source of topographic data over the ice sheets but the horizontal resolution of such data is coarse satellite radar interferometry uses the phase difference between pairs of synthetic aperture radar sar images to measure both ice sheet topography and surface displacement we have applied this technique using ers 1 sar data to make detailed i e 80 m horizontal resolution maps of surface topography in a 100 km by 300 km strip in west greenland extending northward from just above jakobshavns isbrae comparison with a 76 km long line of airborne laser altimeter data shows that we have achieved a relative accuracy of 2 5m along the profile these observations provide a detailed view of dynamically supported topography near the margin of an ice sheet in the final section we compare our estimate of topography with phase contours due to motion and confirm our earlier analysis concerning vertical ice sheet motion and complexity in ers 1 sar interferograms

surface motion of mountain glaciers derived from satellite optical imagery a complete and detailed map of the ice velocity field on mountain glaciers is obtained by cross correlating spot5 optical images this approach offers an alternative to sar interferometry because no present or planned radar satellite mission provides data with a temporal separation short enough to derive the displacements of glaciers the methodology presented in this study does not require ground control points gcps the key step is a precise relative orientation of the two images obtained by adjusting the stereo model of one slave image assuming that the other master image is well georeferenced it is performed with numerous precisely located homologous points extracted automatically the strong ablation occurring during summer time on the glaciers requires a correction to obtain unbiased displacements the accuracy of our measurement is assessed based on a comparison with nearly simultaneous differential gps surveys performed on two glaciers of the mont blanc area alps if the images have similar incidence angles and correlate well the accuracy is on the order of 0 5 m or 1 5 of the pixel size similar results are also obtained without gcps an acceleration event observed in early august for the mer de glace glacier is interpreted in term of an increase in basal sliding our methodology applied to spot5 images can potentially be used to derive the displacements of the earth s surface caused by landslides earthquakes and volcanoes

using multiple radarsat insar pairs to estimate a full three dimensional solution for glacial ice movement 1 multiple sar interferograms are used to solve for the full 3 dimensional displacement of the surface of the henrietta nesmith glacier in northern ellesmere island canada the approach exploits the incidence angle flexibility of different ascending and descending beam modes and the azimuth angle diversity which occurs when different incidence angles are used at high latitudes line of sight displacements are estimated in 3 different orientations from the terrain corrected unwrapped differential phase and used to solve for the displacements in a local east north up frame uncertainty in the absolute line of sight displacements limits the absolute accuracy for vertical displacement however the relative solution coupled with knowledge of the surface slope allows spaceborne mapping of relative glacier thickening or thinning with unprecedented spatial resolution and with an accuracy of order a millimeter per day

validation of alpine glacier velocity measurements using ers tandem mission sar data five ascending and four descending ers 1 2 tandem mode synthetic aperture radar sar interferometry insar data pairs with useful scene coherence are used to measure the surface flow field of an alpine glacier in the canadian rocky mountains the topographic component of the interferogram phase is calculated by using a digital elevation model dem of the terrain and precise orbit data to reconstruct the ers insar imaging geometry the dem is derived from the canada centre for remote sensing ccrs convair 580 airborne sar interferometer as dual line of sight los measurements are not sufficient to completely resolve the three dimensional 3d surface flow field several different assumptions for determining the missing variables are considered and the 3d surface flow field is estimated by using single and dual los measurements the insar results agree with historic and coincident displacement measurements made using traditional point surveying techniques

tidal motion ice velocity and melt rate of petermann gletscher greenland measured from radar interferometry over a floating glacier ice tongue or an ice shelf the glacier motion measured by a single repeat pass radar interferogram is difficult to analyze because the long term steady motion of the ice is intermixed with its cyclic downward motion induced by tidal forcing multiple interferograms and a quadruple difference technique are necessary to separate the tidal signal from the long term steady motion of the ice an example of application of this technique is given here using ers 1 radar images of petermann gletscher a major outlet glacier of northern greenland tidal displacements are measured with 5 mm statistical noise the long term ice velocity is measured with a precision of 1 m a 1 the inferred tidal displacements agree well with model predictions from a fixed elastic beam with an elastic damping factor of 0 47 0 01 km 1 the hinge line is mapped with a precision of 20 80 m combining the interferometric ice velocities with ice thickness data the glacier ice discharge is calculated at and below the hinge line at the hinge line the ice flux is 12 1 1 km3 a 1 at the ice front calf ice production is only 0 59 km3 a 1 meaning that 95 of the ice that crosses the grounding line melts before it reaches the calving front assuming steady state conditions the melt rate of the glacier tongue averages 12 1 m a 1 with peak values exceeding 20 m a 1 near the hinge line this high melt rate cannot be accommodated by surface ablation alone only about 2 3 m a 1 and is attributed to pronounced basal melting of the ice tongue basal melting often assumed to be negligible in greenland is the dominant process of mass release from the floating section of petermann gletscher

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

investigating mountain glacier motion with the method of sar intensity tracking removal of topographic effects and analysis of the dynamic patterns abstract accurate knowledge of glacier motion variations can provide critical information for assessing glacier mass balance changes for fast flowing high mountain glaciers sar intensity tracking may be the most appropriate technique to measure their motions however due to the slant range imaging mode topographic relief can give rise to pixel disalignments in sar image and then bring errors to sar intensity tracking as a result the application of sar intensity tracking has been limited to sar pairs with short baselines because the use of image pairs with long baselines would suffer significant topographic effects over mountainous regions this paper presents an improvement to sar intensity tracking by adding an explicit procedure of topographic correction such correction will not only significantly increase the accuracy of the sar pairs with shorter baselines but also allow the image pairs with longer baselines to be taken advantage of instead of letting them to be dismissed otherwise using the improved sar intensity tracking technique we derive the highly precise motion variation patterns of 11 giant glaciers in tuomuer khan tengri mountain ranges one of the largest glacial centers in tien shan the results manifest that most glaciers there saw flow deceleration during the observation interval 6 january 2007 4 march 2011 except the northern and southern inylchek glacier regarding the glacier motion mechanism ice thermal character and climate features there we deduce that the flow acceleration and deceleration should be the sign of glacier mass gain and loss respectively and the sharp and slight flow decelerations should correspond to remarkable and mild mass loss respectively we confirm these deductions by exploring the close link between the long term motion variations and the dynamic patterns of these glaciers the obvious diversities of the dynamic patterns among the studied glaciers are ascribed to the discrepancies of the glaciers location and scale longer observations are still needed to confirm or redefine these findings in the future though provided that the precipitation keeps increasing whether the glaciers in tuomuer khan tengri mountain ranges will regain mass or not has not been determined yet

flow patterns of lobate debris aprons and lineated valley fill north of ismeniae fossae mars evidence for extensive mid latitude glaciation in the late amazonian a variety of late amazonian landforms on mars have been attributed to the dynamics of ice related processes evidence for large scale mid latitude glacial episodes existing within the last 100 million to 1 billion years on mars has been presented from analyses of lobate debris aprons lda and lineated valley fill lvf in the northern and southern mid latitudes we test the glacial hypothesis for lda and lvf along the dichotomy boundary in the northern mid latitudes by examining the morphological characteristics of lda and lvf surrounding two large plateaus proximal massifs and the dichotomy boundary escarpment north of ismeniae fossae centered at 45 3n and 39 2e lineations and flow directions within lda and lvf were mapped using images from the context ctx camera the thermal emission imaging spectrometer themis and the high resolution stereo camera hrsc flow directions were then compared to topographic contours derived from the mars orbiter laser altimeter mola to determine the down gradient components of lda and lvf flow observations indicate that flow patterns emerge from numerous alcoves within the plateau walls are integrated over distances of up to tens of kilometers and have down gradient flow directions smaller lobes confined within alcoves and superposed on the main lda and lvf represent a later less extensive glacial phase crater size frequency distributions of lda and lvf suggest a minimum youngest age of 100 ma the presence of ring mold crater morphologies is suggestive that lda and lvf are formed of near surface ice rich bodies from these observations we interpret lda and lvf within our study region to result from formerly active debris covered glacial flow consistent with similar observations in the northern mid latitudes of mars glacial flow was likely initiated from the accumulation and compaction of snow and ice on plateaus and in alcoves within the plateau walls as volatiles were mobilized to the mid latitudes during higher obliquity excursions together with similar analyses elsewhere along the dichotomy boundary these observations suggest that multiple glacial episodes occurred in the late amazonian and that lda and lvf represent significant reservoirs of non polar ice sequestered below a surface lag for hundreds of millions of years

seasonal and interannual ice velocity changes of polar record glacier east antarctica we present a study of seasonal and interannual ice velocity changes at polar record glacier east antarctica using ers 1 2 envisat and palsar data with d insar and intensity tracking ice flow showed seasonal variations at the front of the glacier tongue velocities in winter were 19 less than velocities during summer no significant interannual changes were detected ice velocities in the grounding zone and grounded glacier did not show clear seasonal or interannual changes the distribution of the seasonal variations suggests that the cause for the changes should be localized possible causes are seasonal sea ice changes and iceberg blocking satellite images show that the sea ice surrounding polar record glacier undergoes seasonal changes frozen sea ice in winter slowed the huge iceberg and provided increased resistance to the glacier flow the interaction between the glacier tongue iceberg and sea ice significantly influences their flow pattern

accuracy of topographic maps derived from ers 1 interferometric radar an interferometric radar technique for topographic mapping of surfaces promises a high resolution approach to the generation of digital elevation models the authors present analyses of data collected by the synthetic aperture radar instrument on board the ers 1 satellite on successive orbits use of a single satellite in a nearly repeating orbit is attractive for reducing cost and spaceborne hardware complexity also it permits inference of changes in the surface from the correlation properties of the radar echoes the data have been reduced to correlation maps and digital elevation models the correlation maps show that temporal correlation decreases significantly with time but not necessarily at a constant well defined rate likely depending on environmental factors when correlation among passes remains high however it is possible to form digital elevation models analyses of noise expected in ers 1 interferometric data collected over alaska and the southwestern united states indicate that maps with relative errors less than 5 m rms are possible in some regions however orbit uncertainties imply that tie points are required in order to reduce absolute height errors to a similar magnitude the authors find that about 6 tie points per 40 spl times 40 km scene with 5 m rms or better height accuracy are needed to keep systematic map height errors below 5 m rms the performance of the ers 1 radar system for topographic applications though useful for a variety of regional and local discipline studies may be improved with respect to temporal decorrelation errors and absolute height acuity by modifying the orbit repeat period and incorporating precise orbit determination techniques the resulting implementation will meet many but not all objectives of a global mapping mission

flow and structure in a dendritic glacier with bedrock steps sherpa romeo green journal open access article creative commons attribution 4 0 international cc by 4 0 applies

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

evaluation of remote sensing techniques to measure decadal scale changes of hofsjokull ice cap iceland dynamic surficial changes and changes in the position of the firn line and the areal extent of hofsjokull ice cap iceland were studied through analysis of a time series 1973 98 of synthetic aperture radar sar and landsat data a digital elevation model of hofsjokull which was constructed using sar interferometry was used to plot the sar backscatter coefficient vs elevation and air temperature along transects across the ice cap seasonal and daily patterns are caused by freezing or thawing of the ice cap surface and abrupt changes in are noted when the air temperature ranges from 5 to 0 c late summer 1997 sar and reflectance landsat boundaries agree and appear to be coincident with the firn line and a sar boundary that can be seen in the january 1998 sar image in january 1994 through 1998 the elevation of this boundary on the ice cap was quite stable ranging from 1000 to 1300 m while the equilibrium line altitude as measured on the ground varied considerably thus the equilibrium line may be obscured by firn from previous years techniques are established to measure long term changes in the elevation of the firn line and changes in the position of the ice margin

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

the integration of jers 1 and ers sar in differential interferometry for measurement of complex glacier motion complex glacier motion in the grove mountains region antarctica is measured using four pass differential synthetic aperture radar sar interferometry insar the components of the motion vector field are resolved using a 44 day separation japanese earth resources satellite 1 jers 1 insar pair and a european remote sensing satellite 1 2 ers 1 2 tandem insar pair the 44 day temporal baseline provides the sensitivity required to observe the range of ice motion around 8 10 m a 1 and the 1 day short baseline provides the best choice for glacier digital elevation model reconstruction it is remarkable that the scattering field of the jers 1 pair remained coherent over the long time interval and the interferometric fringes are clear the overall ice flow is from east to west downslope and towards lambert glacier the regional flow is obstructed by nunataks extending north south with two wide gaps two narrow glaciers flow past the nunataks and rejoin each other at the downstream end regional morphology and the resolved flow in the grove mountains area suggests that ice flow is channeled throughout this eastern flank of lambert glacier

interferometric estimation of three dimensional ice flow using ascending and descending passes satellite radar interferometry sri provides an important new tool for determining ice flow velocity interferometric measurements made from a single track direction are sensitive only to a single component of the three component velocity vector observations from along three different track directions would allow the full velocity vector to be determined a north south looking synthetic aperture radar sar could provide these observations over large portions of the globe but not over large areas of the polar ice sheets the authors develop and demonstrate a technique that allows the three component velocity vector to be estimated from data acquired along two track directions ascending and descending under a surface parallel flow assumption this technique requires that there are accurate estimates of the surface slope which are also determined interferometrically to demonstrate the technique the authors estimate the three component velocity field for the ryder glacier greenland their results are promising although they do not have yet ground truth data with which to determine the accuracy of their estimates

repeat pass interferometry with airborne synthetic aperture radar it is shown that interference can be observed by coherently combining pairs of either x or c band airborne synthetic aperture radar sar images from separate passes over the same test site coherence between separate images is obtained only if the aircraft is flown and the data are processed in such a way that each resolution cell in the two images is viewed with very nearly the same geometry successful repeat pass interferometric results were obtained from those passes flown by the ccrs convair 580 aircraft with flight line offsets of less than a few tens of meters a summary of the experiment the phase correction of nonrectilinear aircraft motion and the subsequent data processing is provided

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

rock glacier nomenclature a re assessment several contentious issues have arisen from rock glacier nomenclature for example whether the term rock glacier implies genesis from glacial ice or genesis from permafrost the situation is compounded since rock glacier classification may be based on several different parameters some of which are measured and quantified others inferred these include gross morphology dynamics processes of formation location internal characteristics thermal regime and age uncertainties in specifying the genesis in the light of the potential complexity means that definitions should be related to recognisable topographic forms which allow mapping of such features the distinction is made between rock glaciers sensu stricto which follows the original descriptions and typology of the early years of the 20th century and protalus lobes the forms can usually be differentiated in terms of length breadth ratios as well as by their relative locations some of the most common issues of contention within rock glacier research can be solved by this approach

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

glaciological advances made with interferometric synthetic aperture radar spaceborne interferometric synthetic aperture radar insar techniques for measuring ice flow velocity and topography have developed rapidly over the last decade and a half revolutionizing the study of ice dynamics spaceborne interferometry has contributed to major progress in many areas of glaciological study by providing the first comprehensive measurements of ice stream flow velocity over the major outlets of greenland and antarctica revealing that ice stream and outlet glacier flow can change rapidly months to years improving understanding of several ice sheet and ice shelf processes providing velocity for flux gate based mass balance assessment mapping flow of mountain glaciers and capturing the geomorphic traces of past ice flow we review the basic technique development the measurement characteristics and the extensive set of results yielded by these measurements

discovering anomalous dynamics and disintegrating behaviour in glaciers of chandra bhaga sub basins part of western himalaya using dinsar abstract glacier velocity is one of the important parameters to know about glacier dynamics its mass and health understanding glacier velocity also assists in the analysis of ice thickness ice flux and mass balance furthermore basin sub basin wise studies are helpful to understand the climate change over that region instead of monitoring individual glaciers in the current study the spatial distribution of glacier velocity is generated for the entire chandra and bhaga sub basins in the lahaul spiti district of himachal pradesh india using advanced land observing satellite 2 phased array type l band synthetic aperture radar 2 alos 2 palsar 2 differential interferometry pair images with a 14 days temporal gap the glaciers in chandra sub basin are found to have a high flow rate as compared to the glaciers in bhaga sub basin local slope and ice thickness which decrease towards the terminus in general control the movement of valley glaciers and lower movement rate is observed for most of glaciers towards the terminus frontal area however a few glaciers of bhaga sub basin demonstrate an accelerated movement in their frontal areas this irregular behaviour is also studied in this work and it is discovered that terrain slope and influx of melting water from adjacent glaciers are the major causes for such behaviour of these glaciers they are therefore prone to accelerated mass loss compared to other glaciers in the sub basin another key finding of the anomalous glacier dynamics study is the disintegrating behaviour of glaciers which is also identified by interpreting the responses of physical scattering mechanisms retrieved from glaciers using fully polarimetric alos 2 palsar 2 warming temperatures are expected to cause glacier retreat and separation of tributary glaciers from the main glacier body melt water from tributary glaciers can further accelerate glacier flow and ice melt in lower part of glacier trunk this can lead to formation of dead ice zones and disintegration of himalayan glaciers which are supported by numerous tributary glaciers therefore we expect that the loss in glacier area due to warming will be larger than the present prediction where mass loss is considered from conventional way