Search Results (26)

Glacier mass balance and ice flow dynamics, strongly influenced by climatic variability, topography, and geological–structural controls, can be precisely characterized through in situ GPS measurements of surface ice velocity, though such data remain limited due to logistical challenges in field acquisition. This study presents direct measurements of surface ice velocity on Grey Glacier, a major outlet glacier of the Southern Patagonian Icefield (SPI) in Chile. Ice flow was monitored over a one-week period in late 2002 by tracking the displacement of six stakes installed on the glacier surface. The resulting velocity data reveal spatial patterns of surface flow that provide significant information for the comparison and validation of remote sensing observations, which is particularly relevant considering that the ice mass from which the data were collected has since disappeared due to glacier retreat. The combined use of ground-based and remote sensing methods is essential for advancing our understanding of glacier motion and behavior, particularly in the context of climate forcing. Full article

With an area of 13,000 km² and more than 60 outlet glaciers (tidewater or lake-terminating), the Southern Patagonian Icefield (SPI) stores a substantial volume of freshwater, and its accelerating melt contributes to global sea level rise. In addition to monitoring frontal retreat and ice thinning, tracking near-terminus glacier surface velocity can provide key insight into glacier dynamics. Here, we aimed to understand the current state of the SPI and to explore the dynamic restructuring of the glaciers in comparison with previous results. Considering that ice velocity acceleration near termini can be indicative of a drastic ice thinning and calving, during 2019–2020, we investigated the surface velocity of glaciers in the SPI using feature and speckle tracking. We calculated velocity maps (450 in total) from Sentinel-1 SAR images. Velocity ranged from 0 to 6571 myr⁻¹ for the whole study period, taking into account the 846 one square kilometer subsamples. Mean values of the topographic parameters (elevation, slope, aspect) have variable correlation with the mean velocity values, while mean ice thickness does not have a strong correlation with velocity. Nevertheless, mean velocities show association between near-frontal motion acceleration and calving, as observed in tidewater glaciers and four lake-terminating glaciers. Considering along-length changes in the glaciers, it is found that there are glaciers with upward increasing velocities, downward increasing velocities, and with a single velocity peak and multiple velocity peaks. Comparing our measurements with previous studies, we found major dynamic changes in several glaciers. A massive calving event at Pío XI Glacier significantly affected its velocity for months. The slowdown observed at 13–14 km from the terminus of the Jorge Montt Glacier contrasts with all previous studies that showed an acceleration of the glacier in this area. Our observations indicate rapid changes in some of the SPI glaciers, which suggests their unstable state. Full article

The first comprehensive mass balance estimation for the world’s largest tropical icefield is presented. Geodetical mass balance was calculated using photogrammetry from aerial and satellite images spanning from 1955 to 2024. The results meet expected quality standards using some new satellite sources, such as the Peruvian PeruSAT-1, although the quality of airborne imagery is consistently lower than that of satellite sources. The Nevado Coropuna icefield remained almost stable between 1955 and 1986 with −0.04 m dh yr⁻¹. Since then, it has undergone a sustained and accelerated negative mass balance, reaching a maximum annual dh yr⁻¹ of −0.73 ± 0.19 in the 2020–2023 timeframe. The glacier loss is not equal across the entire ice mass, but more acute in the northern and northeastern outlet tongues. Debris-covered ice and rock glaciers show a much weaker negative mass balance signal. The impact of ENSO events is not evident in the overall ice evolution, although their long-term relevance is acknowledged. Overall, the negative response of Nevado Coropuna to global warming (−0.36 ± 0.12 m.w.e. yr⁻¹ for the 2013 to 2024 period) is less pronounced than that of other Peruvian glaciers, but more severe than that reported for the nearby Dry Andes of Chile and Argentina. Full article

The Patagonia Icefield, the largest ice mass in the Southern Hemisphere outside Antarctica, has experienced significant growth and expansion of ice-contact lakes in recent decades, with lake surface water temperature (LSWT) being one of the key influencing factors. LSWT affects glacier melting at the waterline and accelerates glacier mass loss. However, the observations of ice-contact LSWT are often limited to short-term, site-based field measurements, which hinders long-term, whole-lake monitoring. This study examines LSWT for the three largest ice-contact lakes in the Patagonia Icefield—Lake Argentino, Lake Viedma, and Lake O’Higgins, each exceeding 1000 km²—and the three largest nearby non-ice-contact lakes for comparison using MODIS data between 2002 and 2022. In 2022, the mean LSWTs for Lake Argentino, Lake Viedma, and Lake O’Higgins were 7.2, 7.0, and 6.4 °C, respectively. In summer, ice-contact lakes exhibited wider LSWT ranges and more pronounced cooling near glacier termini and warming farther away compared to other seasons, demonstrating glacier melt cooling and its seasonal variability. Over the past 20 years, both Lake Viedma and Lake O’Higgins showed a warming rate of +0.20 °C dec⁻¹, p > 0.1, with slower warming near the glacier, reflecting glacier contact suppression on the LSWT trend. Conversely, Lake Argentino displayed a significant warming rate of +0.43 °C dec⁻¹ (p < 0.05), with faster rates near the glacier terminus, possibly linked to a prolonged and large (>64 km²) iceberg accumulation event from March 2010 to October 2011 in Glacier Upsala’s fjord. Iceberg mapping shows that larger events caused more pronounced short-term (24 days) LSWT cooling in Lake Argentino’s ice-proximal region. This study highlights the role of glacier–lake interactions including calving events in regulating ice-contact lake water temperature. Full article

This paper investigates the ability of a relatively low cost, commercially available uncrewed aerial vehicle (UAV), the DJI Mavic 3 Multispectral, to perform cryospheric research. The performance of this UAV, where applicable, is compared to a similar but higher cost system, the DJI Matrice 350, equipped with a Micasense RedEdge-MX Multispectral dual-camera system. The Mavic 3 Multispectral was tested at three field sites: the Lemon Creek Glacier, Juneau Icefield, AK; the Easton Glacier, Mt. Baker, WA; and Bagley Basin, Mt. Baker, WA. This UAV proved capable of mapping the spatial distribution of red snow algae on the surface of the Lemon Creek Glacier using both spectral indices and a random forest supervised classification method. The UAV was able to assess the timing of snowmelt and changes in suncup morphology on snow-covered areas within the Bagley Basin. Finally, the UAV was able to classify glacier surface features using a random forest algorithm with an overall accuracy of 68%. The major advantages of this UAV are its low weight, which allows it to be easily transported into the field, its low cost compared to other alternatives, and its ease of use. One limitation would be the omission of a blue multispectral band, which would have allowed it to more easily classify glacial ice and snow features. Full article

Cross-correlation of image-pairs derived from both optical and synthetic aperture radar satellite imagery is the most common technique for measuring glacier flow velocity and quantifying the dynamics and discharge of glaciers. While the technique has been shown to be effective on polar ice sheets, the accuracy of satellite-derived velocities in temperate alpine regions is poorly constrained. Flow velocities were measured in situ using an RTK-GPS along four profiles on Taku, Matthes, Vaughan-Lewis, and Llewellyn Glaciers in southeast Alaska from 2016 through 2018. These GNSS-measured velocities were correlated against spatially coincident and contemporaneous satellite-derived velocity datasets, including both versions 1 and 2 of ITS_LIVE and velocities determined by offset tracking of SAR data in the Sentinel Application Platform (SNAP) and GAMMA (RETREAT dataset). Significant gaps in velocity maps derived from optical imagery (Landsat/Sentinel-2) were observed and determined to be due to low coherence rather than cloud contamination. Cross-correlation of SAR data (Sentinel-1) in SNAP and RETREAT achieved better accuracy compared to optical, although a strong dichotomy in performance was observed. SAR-derived velocities in the accumulation zone and transient snowline area showed overall poor correlation to GNSS-measured velocities that were likely due to significant shifts in the backscatter amplitude of the homogenous, snow-covered surface, although both SAR-derived SNAP and RETREAT velocities were anomalously accurate where GNSS velocities were below 0.10 m/day along the glacier margins. SNAP and RETREAT achieved the most accurate results in the study in the ablation zone of the Llewellyn Glacier where stable backscatter targets on the glacier surface (crevasses, supraglacial debris) facilitated high coherence in the cross-correlation procedure. SAR data are likely the most suitable for the derivation of satellite-derived velocities on temperate alpine glaciers, particularly in slow-moving and ablation zones, but should be subject to scrutiny for fast-flowing glaciers and those with an active hydrologic surface system. Full article

Soajo Mountain is located in the northwestern Iberian Peninsula near the border between Portugal and Spain. Its highest elevation is 1416 m at the Pedrada summit. During the Pleistocene, the cascade cirques on the east flank and the icefield that covered the flattened surface of the high plateau generated several glacier valleys. This study presents a paleoglacial reconstruction of the relict glacial landscape in Soajo Mountain for the Glacial Maximum Extent (GME) through the following methods: (1) a detailed geomorphological map supported by high-resolution orthophotography, digital elevation models with a spatial resolution of 70 cm, and field surveys; (2) the delineation of the glacial surface, and the calculation of the glacial flowlines to obtain the numerical model of the ice thickness; and (3) an estimation of the paleoELA altitudes. The paleoglacial reconstruction, using GlaRe methodology, reveals a glacial surface of 16 km², including an icefield on the Lamas de Vez plateau (mean elevation of 1150 m) and a radial glacial flow to the east and north. The arrangement of the glaciated area attests to the topographic, lithological, and structural conditioning on the development of small glacial tongues, with an emphasis on the ice tongue flowing northwards, with a thickness of 173 m and a length of 2.92 km. The Soajo GME paleoglacier comprises three main glacial sectors: Lamas de Vez Icefield, Vez and Aveleira Valleys, and the Eastern Glacial Sector. These paleoglaciers have achieved maximum ice volumes of 214.4 hm³, 269.2 hm³, and 115.8 hm³, respectively, with maximum ice thicknesses of 127 m, 173 m, and 118 m, respectively. On the west flank, a smaller paleoglacier named Branda da Gémea recorded an ice volume of 24.3 hm³ and a maximum ice thickness of 110 m. According to the ELA-AABR method, Soajo Mountain has one of the lowest ELA values in the Iberian NW, ranging from 1085 to 1057 m. This is due to its oceanic location, an orographic barrier effect, and the influence of the polar front. Full article

The Trevinca Massif is in the northwestern Iberian Peninsula, on the border between Galicia and Castilla-León. Its highest elevation is 2124 m at the Trevinca peak. During the Pleistocene, an extensive icefield developed in this area, occupying the flattened surfaces in the high massif zones, and generating several glacier valleys. In the occidental sector, the identified paleoglaciers reached 187 km², and glacier tongues up to 30 km in the Bibei valley, where the ice thickness came to 527 m. The glacial forms and deposits were mapped and analyzed in the entire Trevinca massif, whereas the paleoglacial reconstruction was carried out in the occidental sector (previous works analyzed the oriental sector). The reconstruction was performed by using high-resolution orthophotography, digital elevation models with a spatial resolution of 2 m, and fieldwork surveys to identify the primary forms and estimate the ice cover in the past through the GlaRe methodology. Moreover, the paleo-ELA was estimated for this sector, and the values of the ice thickness, the ELA position, and the moraines were related to other nearest sectors to analyze their similarities and differences. Three main paleoglaciers were identified in the occidental Trevinca massif (Xares, Canda, and Bibei-Barxacova). Bibei showed the highest ice thickness and ice extension, occupying more than 140 km² and with a thickness above 500 m some areas. Concerning the ELA, the values varied between the minimum at Xares with 1427 m and the maximum at Bibei-Barxacova with 1839 m. Four groups were identifying based on moraine ridges and were related to the different climatic phases in that sector. Full article

The Southern Patagonian Icefield (SPI) is the largest continuous ice mass in the Southern Hemisphere outside Antarctica. It has been shrinking since the Little Ice Age (LIA) period, with increasing rates in recent years. An uplift of crustal deformation in response to this deglaciation process has been expected. The goal of this investigation is to analyze the crustal deformation caused by ice retreat using time-series data from continuous GPS stations (2015–2020) in the northern area of the SPI. For this purpose, we installed two continuous GPS stations on rocky nunataks of the SPI (the GRCS near Greve glacier and the GBCS close by Cerro Gorra Blanca). In addition, ice elevation changes (2000–2019) were analyzed by the co-registration of the SRTM digital elevation model and ICESat elevation data points. The results of the vertical components are positive (36.55 ± 2.58 mm a⁻¹), with a maximum at GBCS, indicating the highest rate of crustal uplift ever continuously recorded in Patagonia; in addition, the mean horizontal velocities reached 11.7 mm a⁻¹ with an azimuth of 43°. The negative ice elevation changes detected in the region have also accelerated in the recent two decades, with a median $\Delta h$ (elevation change) of −3.36 ± 0.01 m a⁻¹ in the ablation zone. The seasonality of the GPS signals was contrasted with the water levels of the main Patagonian lakes around the SPI, detecting a complex interplay between them. Hence, the study sheds light on the knowledge of the crustal uplift as evidence of the wastage experienced by the SPI glaciers. Full article

Climate warming has become indisputable, and it is now crucial to increase our understanding of both the mechanisms and consequences of climate change. The Antarctic region is subjected to substantial changes, the trends of which have been recognized for several decades. In the South Shetland Islands, the most visible effect of climate change is progressive deglaciation. The following review focuses on past glaciological studies conducted on King George Island (KGI). The results of collected cryosphere element observations are discussed herein in a comprehensive manner. Our analysis showed that there is a lack of temporal as well as spatial continuity for studies on the basic mass balance parameters on the entire KGI ice dome and only Bellingshausen Dome has a relatively long history of data collection. The methodologies of past work, which have improved over time, are also discussed. When studying the glacier front fluctuations, the authors most frequently use a 1956 aerial photography as reference ice coverage. This was the case for seven papers, while other sources are seldomly mentioned. In other papers as many as 41 other sources were used, and therefore comparison to photos taken up to 60 years later can give misleading trends, as small glaciers may have both advanced and retreated in that time. In the case of glacial velocities there is also an apparent lack of consistency, as different glaciers were indicated as the fastest on KGI. Only Lange, Anna, Crystal, Eldred, and eastern part of Usher glaciers were determined by more than one author as the fastest. Additionally, there are gaps in the KGI Ground Penetrating Radar (GPR) survey area, which includes three ice domes: the Warszawa Icefield, the Krakow Icefield, and eastern part of King George Island. Ideas for further work on the topic are also suggested, allowing for easier access to data and thus contributing to a better understanding of glacier development mechanisms. Full article

Remote sensing techniques are frequently applied for the surveying of remote areas, where the use of conventional surveying techniques remains difficult and impracticable. In this paper, we focus on one of the remote glacier areas, namely the Tyndall Glacier area in the Southern Patagonian Icefield in Chile. Based on optical remote sensing data in the form of multi-spectral Sentinel-2 imagery, we analyze the extent of different snow and ice classes on the surface of the glacier by means of pixel-wise classification. Our study comprises three main steps: (1) Labeled Sentinel-2 compliant data are obtained from theoretical spectral reflectance curves, as there are no training data available for the investigated area; (2) Four different classification approaches are used and compared in their ability to identify the defined five snow and ice types, thereof two unsupervised approaches (k-means clustering and rule-based classification via snow and ice indices) and two supervised approaches (Linear Discriminant Analysis and Random Forest classifier); (3) We first focus on the pixel-wise classification of Sentinel-2 imagery, and we then use the best-performing approach for a multi-temporal analysis of the Tyndall Glacier area. While the achieved classification results reveal that all of the used classification approaches are suitable for detecting different snow and ice classes on the glacier surface, the multi-temporal analysis clearly reveals the seasonal development of the glacier. The change of snow and ice types on the glacier surface is evident, especially between the end of ablation season (April) and the end of accumulation season (September) in Southern Chile. Full article

The main goal of this paper is to compare two co-registration methods for geodetic mass balance (GMB) calculation in 28 glaciers making up the Upper Santa Cruz River basin, Southern Patagonian Icefield (SPI), from 1979 to 2018. For this purpose, geospatial data have been used as primary sources: Hexagon KH-9, ASTER, and LANDSAT optical images; SRTM digital radar elevation model; and ICESat elevation profiles. After the analyses, the two co-registration methods, namely M1, based on horizontal displacements and 3D shift vectors, and M2, based on three-dimensional transformations, turned out to be similar. The errors in the GMB were analyzed through a k index that considers, among other variables, the error in elevation change by testing four interpolation methods for filling gaps. We found that, in 63% of the cases, the relative error in elevation change contributes 90% or more to k index. The GMB throughout our study area reported that a loss value of −1.44 ± 0.15 m w. e. a⁻¹ (−3.0 Gt a⁻¹) and an ice thinning median of −1.38 ± 0.11 m a⁻¹ occurred within the study period. The glaciers that showed the most negative GMB values were Upsala, with an annual elevation change median of −2.07 ± 0.18 m w. e. a⁻¹, and Ameghino, with −2.31 ± 0.22 m w. e. a⁻¹. Full article

We mapped flow velocity and calving rates of the iconic Perito Moreno Glacier (PMG), belonging to the Southern Patagonian Icefield (SPI) in the Argentinian Patagonia. We tracked PMG from 2001 to 2017, focusing mostly upon the latest images from 2016–2017. PMG delivers about ca. 10⁶ m³ day⁻¹ of ice in the Lago Argentino, and its front periodically reaches the Peninsula Magallanes. Therein, the PMG causes an ice-dam, clogging Brazo Rico channel, and lifting water level by about 10 m, until ice-dam failure, normally occurring in March. Here, we used 36 pairs of satellite images with a resolution of 10 m (SENTINEL2, visible, 9 pairs of images) and 15 m (LANDSAT imagery, panchromatic, 27 pairs of images) to calculate surface velocity (V_S). We used Orientation Correlation technique, implemented via the ImGRAFT^® TemplateMatch tool. Calving rates were then calculated with two methods, namely, (i) M1, by ice flow through the glacier front, and (ii) M2, by ice flow at 7.5 km upstream of the front minus ablation losses. Surface velocity ranged from about 4 m day⁻¹ in the accumulation area to about 2 m day⁻¹ in the calving front, but it is variable seasonally with maxima in the summer (December–January–February). Calving rate (CR_M) ranges from 7.72 × 10⁵ ± 32% to 8.76 × 10⁵ ± 31% m³ day⁻¹, in line with recent studies, also with maxima in the summer. We found slightly lower flow velocity and calving rates than previously published values, but our estimates cover a different period, and a generally large uncertainty in flow assessment suggests a recent overall stability of the glacier. Full article

Meltwater from glaciers makes significant contributions to general streamflow and provides water for flora and fauna. Continuous glacier monitoring programs enhance our understanding of the impacts of global warming on glaciers and their topographical features. The objective of this study is to measure spatial and temporal changes in Canada’s Columbia Icefield glaciers. This study uses Landsat (TM 5 and OLI) images to delineate glacier extents in the Columbia Icefield between 1985 and 2018. The study also analyzes the retreat of the Athabasca, Castleguard, Columbia, Dome, Saskatchewan, and Stutfield Glaciers. The total area covered by the Icefield in 1985 was 227 km². By 2018, the Icefield had lost approximately 42 km² of its area coverage, representing 18% of its previous coverage. All glaciers in the study region retreated and decreased in area over the study period. The pattern observed in this study is one of general ice loss in the Columbia Icefield, which mirrors patterns observed in other mountain glaciers in Western Canada. Full article

The local climate in Southern Patagonia is strongly influenced by the interaction between the topography and persistent westerlies, which can generate föhn events, dry and warm downslope winds. The upstream flow regime influences different föhn types which dictate the lee-side atmospheric response regarding the strength, spatial extent and phenomenology. We use a combination of observations from four automatic weather stations (AWSs) and high-resolution numerical modeling with the Weather Research and Forecasting (WRF) model for a region in Southern Patagonia (48° S–52° S, 72° W–76.5° W) including the Southern Patagonian Icefield (SPI). The application of a föhn identification algorithm to a 10-month study period (June 2018–March 2019) reveals 81 föhn events in total. A simulation of three events of differing flow regimes (supercritical, subcritical, transition) suggests that a supercritical flow regime leads to a linear föhn event with a large spatial extent but moderate intensity. In contrast, a spatially limited but locally strong föhn response is induced by a subcritical regime with upstream blocking and by a transition regime with a hydraulic jump present. Our results imply that the hydraulic jump-type föhn event (transition case) is the most critical for glacier mass balances since it shows the strongest warming, drying, wind velocities and solar radiation over the SPI. The consideration of flow regimes over the last 40 years shows that subcritical flow occurs most frequently (78%), however transitional flow occurs 14% of the time, implying the potential impact on Patagonian glaciers. Full article