In May of 1990, three research groups from China, the Soviet Union and the United States visited Glacier No. 1 in the Ürümqi river basin, Xinjiang Uygur Autonomous Region, northwestern China, in a cooperative effort to examine differences in mass-balance calculations resulting from sampling and estimation procedures. Three different snow-depth data sets were collected consisting of: (1) high-resolution depth transects covering the glacier, (2) depths taken from the permanent stake network, and (3) an intermediate data set constructed using the stake network and supplementary depth data from locations not covered by the stake network. The glacier was divided into ten elevation zones and the data were registered to a digital elevation model for analysis. Results show that the permanent stake network provides an accurate estimate of total mass balance if certain techniques are used for extrapolation to higher elevations, although estimates of mass balance for particular regions of the glacier are not accurate. Some regions were overestimated while others were underestimated, leading to a good overall estimate. The intermediate-resolution data set provided better within-zone estimates of mass balance, but was less accurate than the stake network for total mass balance.

The two-dimensional wavelet transform is a highly efficient band-pass filter, which can be used to track features in satellite images from sequential paths. Wavelet analysis of NASA scatterometer and Special Sensor Microwave/Imager data has been used to obtain daily sea-ice drift information for the Arctic region. Comparison with ice motion derived from ocean buoys shows good quantitive agreement. Furthermore, the scatterometer results definitely complement passive-microwave radiometer results when there are cloud or surface effects. This outcome allows three sets of sea-ice-drift daily results from scatterometer, radiometer and buoy data to be merged as a composite map by data-fusion techniques. Based on the composite maps, the ice-flow streamlines are highly correlated with surface air-pressure contours. In order to quantify the wind effects on ice motion, empirical orthogonal functions are used in the principal-component analysis to isolate generalized patterns inherent in 6 months (fall/winter) of daily sea-ice motion data. It is found that 30% of sea-ice motion is highly correlated with 50% of the pressure field in modes 1 and 2. For the higher modes, sea-ice motion is also affected by ocean current, bathymetry and coastal boundary and therefore is not highly correlated with the wind field.

Water vapor in snow is responsible for two main processes connected to almost all studies where snow cover is involved: the snow-density change with time and snow recrystallization. Both processes are the result of a balance between evaporation and condensation on individual snow-crystal surfaces. However, such micro-scale mass balance has rarely been considered as a component of “macro-” heat and mass transfer in snow cover. The present work is an attempt to find a way of combining these two mass-exchange processes, as occurs in Nature. Density change and snow recrystallization rates are analyzed based on recently published temperature field observations around individual snow crystals, combined with experimental data on temperature distributions and recrystallization rates in snow under applied temperature gradients.

Accurately measuring and monitoring the thickness distribution of thin ice is crucial for accurate estimation of ocean–atmosphere heat fluxes and rates of ice production and salt flux in ice-affected oceans. Here we present results from helicopter-borne brightness temperature (TB) measurements in the Southern Ocean in October 2012 and in the Sea of Okhotsk in February 2009 carried out with a portable passive microwave (PMW) radiometer operating at a frequency of 36 GHz. The goal of these measurements is to aid evaluation of a satellite thin-ice thickness algorithm which uses data from the spaceborne Advanced Microwave Scanning Radiometer–Earth Observing System AMSR-E) or the Advanced Microwave Scanning Radiometer-II (AMSR-II). AMSR-E and AMSR-II TB agree with the spatially collocated mean TB from the helicopter-borne measurements within the radiometers’ precision. In the Sea of Okhotsk in February 2009, the AMSR-E 36GHz TB values are closer to the mean than the modal TB values measured by the helicopter-borne radiometer. In an Antarctic coastal polynya in October 2012, the polarization ratio of 36GHz vertical and horizontal TB is estimated to be 0.137 on average. Our measurements of the TB at 36 GHz over an iceberg tongue suggest a way to discriminate it from sea ice by its unique PMW signature.

For the study of drifting snow a pulse-counting device was developed. The detector is sensitive to the momentum transfer of individual snow particles to an exposed surface. More than 105 particles can be counted per cm2/s. The sensor is adjusted to snow particles of 30–200 μm in diameter and a velocity range of 5–30 m/s. A multi-channel analyzer system is used for data handling and to display the momentum spectrum in real time.

A three-dimensional (3-D), high-resolution, non-linearly viscous,non-isothermal ice-sheet model is employed to calculate the “present-day”equilibrium regime of the Antarctic ice sheet and its evolution during thelast glacial cycle. The model is augmented by an approximate formula forice-sheet basal temperature, based on a scaling of the thermodynamicequation for the ice flow. Steady-state solutions for both the shape andextent of the areas of basal melting (or freezing) are shown to be in goodagreement with those obtained from the solution of the full 3-Dthermodynamic equation. The solution for the basal temperature field of theWest Antarctic Siple Coast produces areas at the pressure-melting pointseparated by strips of frozen-to-bed ice, the structure of which isreminiscent of Ice Streams A–E. This configuration appears to be robust,preserving its features in spite of climatic changes during the last glacialcycle. Ice Stream C seems to be more vulnerable to stagnation, switching toa passive mode at least once during the penultimate interglacial. Weconjecture that the peculiarities of local topography determine the uniquebehavior of Ice Stream C: reduced basal stress and, consequently, relativelyweak warming due to internal friction and basal sliding is not able tocounteract the advective cooling during the periods of increased snowfallrate.

As an inhomogeneous mixture of pure ice, brine, air and solid salts the physical properties of sea ice depend on its highly temperature-dependent microstructure. Understanding the microstructure and the way it responds to variations in temperature and salinity is crucial in developing an improved understanding of the interaction between sea ice and the environment. However, measurements monitoring the internal structure of sea ice are difficult to obtain without disturbing its natural state. We have recently developed an application of cross-borehole d.c. resistivity tomography to make in situ measurements that resolve the anisotropic resistivity structure of first-year sea ice. We present results from measurements made in 2008 off Barrow, Alaska, and in 2009 off Ross Island, Antarctica. the sea ice in these two regions forms in different environments: at Barrow, relatively quiescent conditions typically lead to a predominance of columnar ice, while more turbulent conditions and underwater ice formation in McMurdo Sound tend to produce a larger component of frazil or platelet ice. Interpretation of the resistivity measurements carried out in association with temperature and salinity data collected simultaneously allows both observation of the temporal evolution of the ice structure and, in the case of the Antarctic measurements, the identification of different ice types.

Detailed measurements of sediment flux in meltwaters draining from the portal of Gornergletscher, Valais, Switzerland, each ablation season between 1987 and 1990 indicate the nature of interactions between the developing basal drainage system and sediment stored at the glacier subsole. Sediment-flux maxima, which were generally smaller and less frequent later in a season, occurred at times of rising discharge. Overall, sediment flux first increased then decreased during a season. A simple conceptually based model is proposed for the subglacial interaction between flowing meltwater and sediment derived from glacial abrasion. The model was developed in order to allow investigation of relationships between suspended-sediment flux and discharge in meltwaters draining from temperate glaciers, In the model, water spreads out over a grid-square bed such that the area of subsole integrated with flow is a function of discharge. Sediment is abraded from the bed at a uniform rate in cells not covered by water. In winter, sediment accumulates over almost all the bed. Periods of rising flow at the start of the ablation season lead to drainage net expansion, much entrainment of stored sediment and large flux events in portal meltwaters. The model allows redistribution and deformation of stored sediment in two directions. Sediment squeezed to the margins of the wetted area throughout summer provides the background level of sediment flux between events. Reduction in total channel-margin length with progressive changes in drainage-network topology explains declining background flux later in summer. The model replicates well the timing, but not the absolute and relative magnitudes, of sediment-flux maxima in portal meltwaters draining from Gornergletscher.

Tropical glaciers have undergone significant shrinkage or complete disappearance due to climate change. Based on geodetic observations and remote sensing data, this study presents a comprehensive chronology of the extinction of Carihuairazo Ice Cap (Kari-Huayra-Razu in Quichua), located in the Ecuadorian Andes, from 1956 to 2020. The cumulative glacier mass balance over the 1956–2020 period was − 31.40 m w.e. (−0.49 ± 0.04 m w.e. a−1), determined over three periods of ice loss 1956–2005, 2005–2011, and 2011–2020, during which the annual average mass balance was − 0.41, − 0.77 and − 0.75 m w.e. a−1, respectively. The loss of glacier mass led to total glacier shrinkage, with a pronounced acceleration between 1978 and 1986, after which the glaciers retreated rapidly and disappeared by 2024. The ice cap experienced an average annual area loss of 3 % a−1 since the 1980s, a trend two times as high as that reported for the Antisana Ice Cap during a similar period.

Studies of palaeo-accumulation rates at Dome A, East Antarctica, are entirely absent. Here, spatio-temporal variations in ice accumulation rates for the past ~161 ka are calculated from isochronous internal layering, traced from radio-echo sounding (RES) data collected by the Polar Research Institute of China (PRIC) during the 21st CHINARE. The layers are dated by linking them to the site of Vostok ice core along an RES profile, which was flown by the Alfred-Wegener-Institut (AWI) in the Dome Connection East Antarctica (DoCo) project. The Dansgaard-Johnsen model is used to determine the spatial and temporal pattern of ice accumulation in Dome A region. The results show that there is a slight increasing pattern of ice accumulation from south to north along the 216 km radar profile at Dome A. The lowest ice accumulation rates were calculated around the Dome A zone. In the past ~90 ka, there were relatively high accumulation rates during the time period 34–47 ka (Marine Isotope Stage 3) at Dome A.

The cryosphere is represented in some hydrological models by the arealextent of snow cover, a variable that has been operationally available inrecent years through remote sensing. In particular, the snowmelt–runoffmodel (SRM) requires the remotely sensed snow-cover extent as a major inputvariable. The SRM is well-suited for simulating the hydrological response ofa basin to hypothetical climate change because it is a non-calibrated model.In order to run the SRM in a climate-change mode, the response of the arealsnow cover to a change in climate is critical, and must be calculated as afunction of elevation, precipitation, temperature, and snow-waterequivalent. For the snowmelt-runoff season, the effect of climate change onconditions in the winter months has a major influence. In a warmer climate,winter may experience more rain vs snow events, and more periods of wintersnowmelt that reduce the snow water equivalent present in the basin at thebeginning of spring snowmelt. As a result, the spring snowmelt runoff underconditions of climate warming will be affected not only by differenttemperatures and precipitation, but also by a different snow cover with achanged depletion rate. A new radiation-based version of the SRM is underdevelopment that will also take changes in cloudiness and humidity intoaccount, making climate-change studies of the cryosphere even morephysically based.

The Seal Nunataks ice shelf (SNIS, ~743 km2 in 2013) is an unofficial name for a remnant area between the former Larsen A and Larsen B ice shelves off the northeastern Antarctic Peninsula. Analyses using Landsat 7 ETM+ and Terra ASTER images from 2001 to 13 and ICESat altimetry from 2003 to 09 show it has retreated and thinned following the Larsen A (1995) and Larsen B (2002) disintegrations. Despite some regional cooling and more fast ice since 2008, SNIS continues to lose ice along its margins and may be losing contact with some nunataks. Detailed analysis of data from four ICESat tracks indicates that ice shelf thinning rates range between 1.9 and 2.7 m a−1, and generally increase from west to east. An ICESat repeat track crossing the adjacent Robertson Island shows a mean elevation loss of 1.8 m a−1. Two tracks crossing the SNIS's remaining tributary, Rogosh Glacier, show sub-meter elevation losses. Comparing shelf remnant and grounded ice thinning rates implies that basal ocean melting augments SNIS thinning by ~1 m a−1, a rate that is consistent with other estimates of ocean-driven shelf thinning in the region.

A large problem of the World Glacier Inventory is the Pakistan part which is still missing. The available official quarter-inch and half-inch maps of the Survey of India and Pakistan are not adequate for the purpose. The maps of some expeditions provide reliable data for a few areas. Landsat imagery does not yield heights and has other disadvantages. At the present time, the Spacelab mission, in September 1986, with its metric camera, seems to offer a rather good opportunity.

We analyze the internal structure of two polythermal glaciers, Hurd and Johnsons, located on Livingston Island, Antarctica, using 200 and 750 MHz GPR data collected in 2003/04, 2008/09 and 2016/17 field campaigns. Based on the different permittivities of snow and ice, we determined the thickness distribution of the end-of winter snow cover and of the cold ice layer. Their knowledge is fundamental for mass balance and glacier dynamics studies due to the different densities and rheological properties of such media. The average measured thicknesses for the snow and cold ice layers (the latter including the snow layer) were of 1.44 ± 0.09 and 29.1 ± 1.5 m, and their corresponding maxima were of 2.45 ± 0.21 and 80.8 ± 2.5 m. GPR snow profiling allowed for extension of the coverage of the snow thickness survey, but added little information to that supplied by snow pits, stake readings and manual snow probing, because of the multiplicity of reflections within the seasonal snowpack caused by internal ice layers and lenses. The polythermal structure determined for Hurd Glacier fits into the so-called Scandinavian type, seldom reported for the Antarctic region.

An ice sheet with fixed boundary conditions may have two steady configurations, as shown by a new one-dimensional model including the physics and continuity of ice, water, and deforming subglacial till. In one steady state, a steep surface slope causes rapid internal ice shearing but forces basal water through subglacial aquifers, suppressing basal velocity; in the other steady state, a gentle surface slope causes only slow ice shearing but allows water to lubricate the ice-bed interface and cause rapid basal velocities. Small climatic forcing may cause large ice-sheet response during a switch between steady states.

The changeable, variable and fragile nature of snow creates unique sampling challenges. In this paper, we present Star: an efficient, field-usable method for use in point-sampling spatial studies. We validate the accuracy of the Star method using a comparative Monte Carlo simulation of 1024 detailed samples of elevation data. As spatial snow studies generally attempt to find spatial continuity in layers and other properties, we use variogram ranges to compare the ability of four sampling methods to accurately reveal such spatial correlation. The three methods compared to Star represent gridded, gridded-random and pure-random methods; Star can be described as a linear-random method. The simulation shows Star’s accuracy to be comparable to both gridded and gridded-random methods. Following this comparative process we introduce a new measure of appropriateness for sampling methods: the correct convergence on a variogram model, which we call correct spatial correlation detection. This directly measures how many sampled areas become correctly classified with either spatially correlated or non-correlated variance for a given variogram model fit. In this measure, Star performs equivalently to the other methods, and in correct convergence it performs as well as pure-random sampling.

Landsat 5 Thematic Mapper observations are used to derive the horizontal distribution of reflectance over Hintereisferner in Austria. To analyze temporal evolution of surface reflectance, three different dates are considered. The retrieval method adopts the linear relation between the planetary and surface reflectance, which follows directly from the principles of invariance. Constants in this linear relation are determined using a simple two-stream radiation model for each of the three days under consideration. From a comparison with observations the retrieved albedo is shown to compare favorably with ground observations.

Bidirectional radiance measurements of various snow-covered surfaces have been acquired using the Advanced Solid-State Array Spectro-radiometer (ASAS) which was flown on the NASA C-130 aricraft over Glacier National Park, Montana on 14 March 1991. A frozen lake, a snow-covered meadow, a mixed coniferous/deciduous forest and a dense coniferous forest were studied. Knowledge of the bidirectional reflectance characteristics of various snow-covered surfaces is key to calculation of albedo from satellite sensors in the future. While the reflectance characteristics of pure snow targets have been measured from the ground, aircraft and satellites, very few bidirectional reflectance data exist for surface covers of mixed snow and vegetation. Analysis of the 14 March 1991 ASAS data show that the anisotropic reflectance of snow was strong over the snow-covered frozen lake but slightly dampened over the meadow because of the presence of low vegetation. Over the dense coniferous forest, strong backscatter was observed while higher radiances in both the forward and aftward sensor view zenith directions was measured over the mixed forest. Snow that was known to be beneath the coniferous forest canopy was not detected in our data.

A dynamic-thermodynamic sea-ice model (Hibler 1979) is used to simulate northern hemisphere sea ice for a 20-year period, 1961 to 1980. The model is driven by daily atmospheric grids of sea-level pressure (geo-strophic wind) and by temperatures derived from the Russian surface temperature data set. Among the modifications to earlier formulations are the inclusion of snow cover and a multilevel ice-thickness distribution in the thermodynamic computations.

The time series of the simulated anomalies show relatively large amounts of ice during the early 1960s and middle 1970s, and relatively small amounts during the late 1960s and early 1970s. The fluctuations of ice mass, both in the entire domain and in individual regions, are more persistent than are the fluctuations of ice-covered area. The ice dynamics tend to introduce more high-frequency variability into the regional (and total) amounts of ice mass. The simulated annual ice export from the Arctic Basin into the East Greenland Sea varies interannually by factors of 3 to 4.

Russian satellite imagery of the polar regions has recently become available to western scientists through Sojuzkarta. The KFA-1000 photographic camera is of particular interest to glaciologists due to its high resolution (a nominal 5 m). Digitized photographic products from this instrument are compared with digital data from Landsat and SPOT series satellites for a partly glacierized area of northwest Spitsbergen. Comparison of KFA-1000 data with detailed maps of man-made structures at the settlement of Ny Ålesund demonstrates that the resolution of the photographic imagery is about 3 m, but scanner resolution limited our digital data to about 6 m. Significantly less detail can be resolved on Landsat TM imagery and Landsat MSS data fail to resolve any of the structures. KFA-1000 data are compared with Landsat TM and MSS images and SPOT HRV multispectral imagery for several tidewater glaciers in Spitsbergen. KFA-1000 imagery is of a significantly higher geometric resolution than the other sensors, allowing the clear identification of individual crevasses and other ice surface features. KFA-1000 scenes from 1985 and 1988 are used to measure ice marginal fluctuations for several northwest Spitsbergen glaciers, and the onset of a surge can also be identified. This imagery has a 60% overlap between scenes and the heighting accuracy of the stereoscopic data is calculated at 45 m. Radiometric analysis of KFA-1000 data is restricted to relative brightness values, since no absolute calibration is available. The photographic products appear speckled, and the range and standard deviation of normalized pixel brightness values over snow is greater than for equivalent Landsat TM data. The very high spatial resolution of the KFA-1000 camera is its principal attraction for glaciologists.