Remote Sensing

Research

Jump to: Other

18 pages, 7071 KiB

Open AccessArticle

Giant Aufeis—Unknown Glaciation in North-Eastern Eurasia According to Landsat Images 2013–2019

by Olga Makarieva, Nataliia Nesterova, Andrey Shikhov, Anastasiia Zemlianskova, Dongliang Luo, Andrey Ostashov and Vladimir Alexeev

Remote Sens. 2022, 14(17), 4248; https://doi.org/10.3390/rs14174248 - 28 Aug 2022

Cited by 12 | Viewed by 2286

Abstract

Based on the analysis of Landsat satellite images over the period of 2013–2019, the number (6683) and total area (4529 km²) of giant aufeis fields (area ≥ 0.1 km²) were estimated for the territory of North-Eastern Eurasia. The contribution [...] Read more.

Based on the analysis of Landsat satellite images over the period of 2013–2019, the number (6683) and total area (4529 km²) of giant aufeis fields (area ≥ 0.1 km²) were estimated for the territory of North-Eastern Eurasia. The contribution of aufeis runoff to river streamflow in different seasons was calculated for 58 hydrological gauges (area 523–526,000 km²). The contribution of aufeis and glaciers to water balance is compared. The aufeis resources vary from 0.4 to 4.25 km³ (or 3.7–11 mm) for individual basins of large rivers. They are at least 10.6 km³ in total or 5 mm of water depth on average for the study area. Aufeis annual runoff varies from 0.3 to 29 mm (0.1–22%, average 3.8%), with the share in winter runoff amount about 6–712% (average 112%) and the spring freshet 0.2–43% (average 7.1%). In general, the aufeis runoff exceeds the glacial runoff. The dynamics of aufeis formation are directly related to winter runoff, whose changes are observed in different parts of the cryosphere. The presented results are relevant for studying the impact of climate change on the hydrological cycle and its components in the permafrost regions of the Northern Hemisphere. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

18 pages, 116090 KiB

Open AccessArticle

Monitoring Regional-Scale Surface Deformation of the Continuous Permafrost in the Qinghai–Tibet Plateau with Time-Series InSAR Analysis

by Zhida Xu, Liming Jiang, Fujun Niu, Rui Guo, Ronggang Huang, Zhiwei Zhou and Zhiping Jiao

Remote Sens. 2022, 14(13), 2987; https://doi.org/10.3390/rs14132987 - 22 Jun 2022

Cited by 8 | Viewed by 2582

Abstract

As an important indicator of permafrost degradation, surface deformation is often used to monitor the thawing and freezing process in the permafrost active layer. However, due to the large area of the continuous permafrost of the Qinghai–Tibet Plateau (QTP) and the large amount [...] Read more.

As an important indicator of permafrost degradation, surface deformation is often used to monitor the thawing and freezing process in the permafrost active layer. However, due to the large area of the continuous permafrost of the Qinghai–Tibet Plateau (QTP) and the large amount of data processed by conventional time-series InSAR, previous studies have mostly focused on local area investigations, and regional characteristics of surface deformation of the continuous permafrost area on the QTP are still unclear. In this paper, we characterized surface deformation in space and time over the main continuous permafrost area on the QTP, by analyzing 11 ascending and 8 descending orbits of Sentinel-1 SAR data acquired between 2018 and 2021 with the time-series InSAR processing system LiCSAR. The reliability of the InSAR deformation results was verified by a combination of leveling measurement data, the intercomparison of overlapping area results, and field verification. The results show that the permafrost regions of the central QTP exhibited the most significant linear subsidence trend. The subsidence trend of permafrost on the QTP was mainly related to the thermal stability of permafrost, and the regions with larger subsidence rates were concentrated in sub-stable, transitional and unstable permafrost areas. We also found that, according to analysis of time-series displacement, the beginning and ending times of permafrost thawing were highly spatially heterogeneous, with the time of maximum thawing depth varying between mid-October and mid-November, which was probably attributed to the active layer thickness (ALT), water content in the active layer, and vegetation cover in these regions. This study is of great significance for understanding the changing trend of permafrost on the QTP under the background of climate change. In addition, this study also demonstrates that combination of Sentinel-1 SAR images with the LiCSAR system has significant potential for detecting permafrost deformation with high accuracy and high efficiency at regional and global scales. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

18 pages, 9562 KiB

Open AccessArticle

Existence of Glacier Anomaly in the Interior and Northern Tibetan Plateau between 2000 and 2012

by Lin Liu, Liming Jiang, Hansheng Wang and Yafei Sun

Remote Sens. 2022, 14(13), 2962; https://doi.org/10.3390/rs14132962 - 21 Jun 2022

Cited by 3 | Viewed by 1753

Abstract

There was sufficient evidence to indicate a nearly balanced glacier mass change (termed glacier anomaly) for Karakoram Mts. since the 1970s, in contrast to worldwide glacier mass losses caused by climate warming. Recently, this anomalous phenomenon was detected over the neighboring western Kunlun [...] Read more.

There was sufficient evidence to indicate a nearly balanced glacier mass change (termed glacier anomaly) for Karakoram Mts. since the 1970s, in contrast to worldwide glacier mass losses caused by climate warming. Recently, this anomalous phenomenon was detected over the neighboring western Kunlun and Pamir Mts. However, the southeastern limit of this glacier anomaly remains uncertain, owing to the paucity of glacier mass balance observations across the interior and northern Tibetan Plateau (INTP). In this study, we presented a decadal glacier mass balance estimation in the INTP by differencing the SRTM DEM with the topographic data produced from TanDEM-X bistatic InSAR images. From 2000 to 2012, decade-average glacier mass balances of between −0.339 ± 0.040 and 0.237 ± 0.078 m w.e. yr⁻¹ were detected over 22 glacierized areas. Significantly, we found a gradient and switch of glacier mass loss over the southeastern portion to glacier mass gain over the northwestern portion. This varying spatial pattern illustrates that glacier anomaly has existed over the northwestern or even central zone of the INTP since the early 21st century. This study provides important evidence for the model simulation of both glacier evolution and atmospheric circulations in investigating the prevailing mechanism of the regional anomalous phenomenon. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

16 pages, 2840 KiB

Open AccessArticle

Laboratory Observations of Preferential Flow Paths in Snow Using Upward-Looking Polarimetric Radar and Hyperspectral Imaging

by Christopher Donahue and Kevin Hammonds

Remote Sens. 2022, 14(10), 2297; https://doi.org/10.3390/rs14102297 - 10 May 2022

Cited by 3 | Viewed by 2231

Abstract

The infiltration of liquid water in a seasonal snowpack is a complex process that consists of two primary mechanisms: a semi-uniform melting front, or matrix flow, and heterogeneous preferential flow paths. Distinguishing between these two mechanisms is important for monitoring snow melt progression, [...] Read more.

The infiltration of liquid water in a seasonal snowpack is a complex process that consists of two primary mechanisms: a semi-uniform melting front, or matrix flow, and heterogeneous preferential flow paths. Distinguishing between these two mechanisms is important for monitoring snow melt progression, which is relevant for hydrology and avalanche forecasting. It has been demonstrated that a single co-polarized upward-looking radar can be used to track matrix flow, whereas preferential flow paths have yet to be detected. Here, from within a controlled laboratory environment, a continuous polarimetric upward-looking C-band radar was used to monitor melting snow samples to determine if cross-polarized radar returns are sensitive to the presence and development of preferential flow paths. The experimental dataset consisted of six samples, for which the melting process was interrupted at increasing stages of preferential flow path development. Using a new serial-section hyperspectral imaging method, polarimetric radar returns were compared against the three-dimensional liquid water content distribution and preferential flow path morphology. It was observed that the cross-polarized signal increased by 13.1 dB across these experiments. This comparison showed that the metrics used to characterize the flow path morphology are related to the increase in cross-polarized radar returns spanning the six samples, indicating that the upward-looking polarimetric radar has potential to identify preferential flow paths. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

29 pages, 7016 KiB

Open AccessArticle

Glacier Recession in the Altai Mountains after the LIA Maximum

by Dmitry Ganyushkin, Kirill Chistyakov, Ekaterina Derkach, Dmitriy Bantcev, Elena Kunaeva, Anton Terekhov and Valeria Rasputina

Remote Sens. 2022, 14(6), 1508; https://doi.org/10.3390/rs14061508 - 20 Mar 2022

Cited by 13 | Viewed by 3257

Abstract

The study aims to reconstruct the Altai glaciers at the maximum of the LIA, to estimate the reduction of the Altai glaciers from the LIA maximum to the present, and to analyze glacier reduction rates on the example of the Tavan Bogd mountain [...] Read more.

The study aims to reconstruct the Altai glaciers at the maximum of the LIA, to estimate the reduction of the Altai glaciers from the LIA maximum to the present, and to analyze glacier reduction rates on the example of the Tavan Bogd mountain range. Research was based on remote sensing and field data. The recent glaciation in the southern part of the Altai is estimated (1256 glaciers with the total area of 559.15 ± 31.13 km²), the area of the glaciers of the whole Altai mountains is estimated at 1096.55 km². In the southern part of Altai, 2276 glaciers with a total area of 1348.43 ± 56.16 km² were reconstructed, and the first estimate of the LIA glacial area for the entire Altai mountain system was given (2288.04 km²). Since the LIA, the glaciers decrease by 59% in the southern part of Altai and by 47.9% for the whole Altai. The average increase in ELA in the southern part of Altai was 106 m. The larger increase of ELA in the relatively humid areas was probably caused by a decrease in precipitation. Glaciers in the Tavan Bogd glacial center degraded with higher rates after 1968 relative to the interval between 1850–1968. One of the intervals of fast glacier shrinkage in 2000–2010 was caused by a dry and warm interval between 1989 and 2004. However, the fast decrease in glaciers in 2000–2010 was mainly caused by the shrinkage or disappearance of the smaller glaciers, and large valley glaciers started a fast retreat after 2010. The study results present the first evaluation of the glacier recession of the entire Altai after the LIA maximum. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

19 pages, 5430 KiB

Open AccessArticle

Specific Effects of the 1988 Earthquake on Topography and Glaciation of the Tsambagarav Ridge (Mongolian Altai) Based on Remote Sensing and Field Data

by Anna Agatova, Roman Nepop, Dmitry Ganyushkin, Demberel Otgonbayar, Semen Griga and Ivan Ovchinnikov

Remote Sens. 2022, 14(4), 917; https://doi.org/10.3390/rs14040917 - 14 Feb 2022

Cited by 4 | Viewed by 1977

Abstract

Strong earthquakes could serve as a trigger for glacier detachment and associated ice–rock avalanches. The 1988 Tsambagarav earthquake (M = 6.4) initiated collapse of part of the glacier tongue and a further ice–rock avalanche with an abnormal 5 km long path in Zuslan [...] Read more.

Strong earthquakes could serve as a trigger for glacier detachment and associated ice–rock avalanches. The 1988 Tsambagarav earthquake (M = 6.4) initiated collapse of part of the glacier tongue and a further ice–rock avalanche with an abnormal 5 km long path in Zuslan valley, Tsambagarav ridge (Mongolian Altai). Early documentation of surface effects in 1988, remote sensing and field data gathered 16 and 30 years after this event allowed for the assessment of the seismic impact on a reduction of “damaged” glacier under conditions of global warming as well as estimating topography changes in this arid and seismically active area. Because of the earthquake, the glacier immediately lost 10.4 % of its area (0.1 km² of tongue surface). Additionally, 56% of its area was lost during 1988–2015, shrinking much faster than neighboring glaciers of similar size and exposition. Collapse of snow–ice cornice in the accumulation zone could play a key role in rapid acceleration of the detached ice block and abnormally long path of the ice–rock avalanche. A large amount of debris material provided more than 16 years of ice melting. Downstream, the valley avalanche debris cover repeats the topography of underlying Pleistocene moraines, which should be considered in regional paleogeographical reconstructions. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Figure 1

12 pages, 4483 KiB

Open AccessArticle

3D Interpretation of a Broadband Magnetotelluric Data Set Collected in the South of the Chinese Zhongshan Station at Prydz Bay, East Antarctica

by Enzhao Xiao, Feng Jiang, Jingxue Guo, Khalid Latif, Lei Fu and Bo Sun

Remote Sens. 2022, 14(3), 496; https://doi.org/10.3390/rs14030496 - 21 Jan 2022

Cited by 2 | Viewed by 2659

Abstract

Antarctica is covered by a thick ice sheet, and the application of geophysical methods is necessary to image the subglacial structures for studying the hydrologic systems and tectonic deformations in the Antarctic continent. The magnetotelluric (MT) method is one of the best approaches [...] Read more.

Antarctica is covered by a thick ice sheet, and the application of geophysical methods is necessary to image the subglacial structures for studying the hydrologic systems and tectonic deformations in the Antarctic continent. The magnetotelluric (MT) method is one of the best approaches to obtain the subglacial electrical resistivities. However, only a very small volume of data has been collected so far in Antarctica using this method. In this paper, we report on a broadband MT profile collected at 10 sites in the south of the Chinese Zhongshan Station at Prydz Bay, and a 3D resistivity model was constructed by inversion of these data. This 3D model shows two low resistivity zones at a depth shallower than 6 km. They are consistent with the low-velocity zones in the previous shear-wave model and can be interpreted as the result of interconnected fluids associated with a downward migration of subglacial water. In addition, a distinct eastward dipping low resistivity zoneis present in the crust, which extends from the top surface to the lower crust. Since its location coincides with the highly positive magnetization named Amery Lineament, it is proposed that this eastward dipping low resistivity zoneextending in the entire crust probably reveals the geometry structure of the Amery Lineament at depth. Besides, it can be inferred from this new 3D resistivity model that the Amery Lineament is at least a crustal-scale structure, which probably outcrops on the land surface but was covered by the ice sheets in the study area. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

20 pages, 8571 KiB

Open AccessArticle

Detection of Surface Crevasses over Antarctic Ice Shelves Using SAR Imagery and Deep Learning Method

by Jingjing Zhao, Shuang Liang, Xinwu Li, Yiru Duan and Lei Liang

Remote Sens. 2022, 14(3), 487; https://doi.org/10.3390/rs14030487 - 20 Jan 2022

Cited by 16 | Viewed by 5901

Abstract

Crevasses are formed by glacier movement and the stresses within glacier ice. Knowledge of the crevasses’ distribution is critical for understanding the glacier and ice shelf stability. In this study, we propose an automated crevasse extraction framework based on Sentinel-1 SAR imagery and [...] Read more.

Crevasses are formed by glacier movement and the stresses within glacier ice. Knowledge of the crevasses’ distribution is critical for understanding the glacier and ice shelf stability. In this study, we propose an automated crevasse extraction framework based on Sentinel-1 SAR imagery and an improved U-Net network. The spatial distribution of crevasses on Antarctic ice shelves in 2020 was mapped with a spatial resolution of ~40 m, and the characteristics of crevasses on the Nickerson Ice Shelf, Jelbart Ice Shelf, Amery Ice Shelf, Thwaites Glacier, and Shackleton Ice Shelf were analyzed. The results indicated the extraction accuracy of our method was 84.2% and the F1 score was 72.5%. Compared with previous published studies, the identification of the crevasse areas had good visual consistency. However, in some scenes, the recall rate was relatively lower due to the quality of the SAR image, terrain surrounding the crevasses, and observation geometry. The crevasses on different ice shelves had different characteristics in terms of length, density, type, and spatial pattern, implying the different stress structures of ice shelves. The Thwaites Glacier and the Nickerson Ice Shelf in the West Antarctica Ice Sheet (WAIS) had shorter ice crevasses, whereas the lengths of ice crevasses on the Jelbart Ice Shelf and the Amery Ice Shelf in the East Antarctica Ice Sheet (EAIS) were relatively long. Nevertheless, there are more closely spaced crevasses on the ice shelf in WAIS compared to that in the EAIS. For the distribution of crevasse types, the Nickerson Ice Shelf and the Shackleton Ice Shelf had various forms of crevasses. There were mainly transverse crevasses developed on the Jelbart Ice Shelf and the Amery Ice Shelf. This study provides a helpful reference and guidance for automated crevasse extraction. The method proposed by this study manifests great application potential and the efficacy of producing a time-series crevasse data set with higher spatial resolution and larger coverage. In the future, more Sentinel-1 SAR imagery will be applied and the effect of temporal and spatial variations in crevasses on the stability of ice shelves will be investigated, which will contribute to project the ice shelf stability and explore the sea level rise implications of recent and future cryosphere changes. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Figure 1

14 pages, 15962 KiB

Open AccessArticle

Ice Cover, Subglacial Landscape, and Estimation of Bottom Melting of Mac. Robertson, Princess Elizabeth, Wilhelm II, and Western Queen Mary Lands, East Antarctica

by Sergey Popov

Remote Sens. 2022, 14(1), 241; https://doi.org/10.3390/rs14010241 - 5 Jan 2022

Cited by 3 | Viewed by 3604

Abstract

This study demonstrates the results of Russian airborne radio-echo sounding (RES) investigations and also seismic reflection soundings carried out in 1971–2020 over a vast area of coastal part of East Antarctica. It is the first comprehensive summary mapping of these data. Field research, [...] Read more.

This study demonstrates the results of Russian airborne radio-echo sounding (RES) investigations and also seismic reflection soundings carried out in 1971–2020 over a vast area of coastal part of East Antarctica. It is the first comprehensive summary mapping of these data. Field research, equipment, errors of initial RES data, and methods of gridding are discussed. Ice thickness, ice base elevation, and bedrock topography are presented. The ice thickness across the research area varies from a few meters to 3620 m, and is greatest in the local subglacial depressions. The average thickness is about 1220 m. The total volume of the ice is about 710,500 km

^{3}

. The bedrock heights vary from 2860 m below sea level in the ocean bathyal zone to 2040 m above sea level in the Grove Mountains area (4900 m relief). The main directions of the bedrock orographic forms are concentrated mostly in three intervals: 345

^{\circ}

–30

^{\circ}

, 45

^{\circ}

–70

^{\circ}

, and 70

^{\circ}

–100

^{\circ}

. The bottom melting rate was estimated on the basis of the simple Zotikov model. Total annual melting under the study area is about 0.633 cubic meters. The total annual melting in the study area is approximately 1.5 mm/yr. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Figure 1

16 pages, 6987 KiB

Open AccessArticle

Grounding Event of Iceberg D28 and Its Interactions with Seabed Topography

by Xuying Liu, Xiao Cheng, Qi Liang, Teng Li, Fukai Peng, Zhaohui Chi and Jiaying He

Remote Sens. 2022, 14(1), 154; https://doi.org/10.3390/rs14010154 - 30 Dec 2021

Cited by 3 | Viewed by 3443

Abstract

Iceberg D28, a giant tabular iceberg that calved from Amery Ice Shelf in September 2019, grounded off Kemp Coast, East Antarctica, from August to September of 2020. The motion of the iceberg is characterized herein by time-series images captured by synthetic aperture radar [...] Read more.

Iceberg D28, a giant tabular iceberg that calved from Amery Ice Shelf in September 2019, grounded off Kemp Coast, East Antarctica, from August to September of 2020. The motion of the iceberg is characterized herein by time-series images captured by synthetic aperture radar (SAR) on Sentinel-1 and the moderate resolution imaging spectroradiometer (MODIS) boarded on Terra from 6 August to 15 September 2020. The thickness of iceberg D28 was estimated by utilizing data from altimeters on Cryosat-2, Sentinel-3, and ICESat-2. By using the iceberg draft and grounding point locations inferred from its motion, the maximum water depths at grounding points were determined, varying from 221.72 ± 21.77 m to 269.42 ± 25.66 m. The largest disagreements in seabed elevation inferred from the grounded iceberg and terrain models from the Bedmap2 and BedMachine datasets were over 570 m and 350 m, respectively, indicating a more complicated submarine topography in the study area than that presented by the existing seabed terrain models. Wind and sea water velocities from reanalysis products imply that the driving force from sea water is a more dominant factor than the wind in propelling iceberg D28 during its grounding, which is consistent with previous findings on iceberg dynamics. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

16 pages, 8907 KiB

Open AccessArticle

Analysis of Temporal and Spatial Variability of Fronts on the Amery Ice Shelf Automatically Detected Using Sentinel-1 SAR Data

by Tingting Zhu, Xiangbin Cui and Yu Zhang

Remote Sens. 2021, 13(17), 3528; https://doi.org/10.3390/rs13173528 - 5 Sep 2021

Cited by 1 | Viewed by 2694

Abstract

The Amery Ice Shelf (AIS) dynamics and mass balance caused by iceberg calving and basal melting are significant in the ocean climate system. Using satellite imagery from Sentinel-1 SAR, we monitored the temporal and spatial variability of the frontal positions on the Amery [...] Read more.

The Amery Ice Shelf (AIS) dynamics and mass balance caused by iceberg calving and basal melting are significant in the ocean climate system. Using satellite imagery from Sentinel-1 SAR, we monitored the temporal and spatial variability of the frontal positions on the Amery Ice Shelf, Antarctica, from 2015 to 2021. In this paper, we propose an automatic algorithm based on the SO-CFAR strategy and a profile cumulative method for frontal line extraction. To improve the accuracy of the extracted frontal lines, we developed a framework combining the Constant False Alarm Rate (CFAR) and morphological image-processing strategies. A visual comparison between the proposed algorithm and state-of-the-art algorithm shows that our algorithm is effective in these cases including rifts, icebergs, and crevasses as well as ice-shelf surface structures. We present a detailed analysis of the temporal and spatial variability of fronts on AIS that we find, an advance of the AIS frontal line before the D28 calving event, and a continuous advance after the event. The study reveals that the AIS extent has been advanced at the rate of 1015 m/year. Studies have shown that the frontal location of AIS has continuously expanded. From March 2015 to May 2021, the frontal location of AIS expanded by 6.5 km; while the length of the AIS frontal line is relatively different after the D28 event, the length of the frontal line increased by about 7.5% during 2015 and 2021 (255.03 km increased to 273.5 km). We found a substantial increase in summer advance rates and a decrease in winter advance rates with the seasonal characteristics. We found this variability of the AIS frontal line to be in good agreement with the ice flow velocity. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Figure 1

14 pages, 2159 KiB

Open AccessArticle

Geodetic Mass Balance of the South Shetland Islands Ice Caps, Antarctica, from Differencing TanDEM-X DEMs

by Kaian Shahateet, Thorsten Seehaus, Francisco Navarro, Christian Sommer and Matthias Braun

Remote Sens. 2021, 13(17), 3408; https://doi.org/10.3390/rs13173408 - 27 Aug 2021

Cited by 8 | Viewed by 3196

Abstract

Although the glaciers in the Antarctic periphery currently modestly contribute to sea level rise, their contribution is projected to increase substantially until the end of the 21st century. The South Shetland Islands (SSI), located to the north of the Antarctic Peninsula, are lacking [...] Read more.

Although the glaciers in the Antarctic periphery currently modestly contribute to sea level rise, their contribution is projected to increase substantially until the end of the 21st century. The South Shetland Islands (SSI), located to the north of the Antarctic Peninsula, are lacking a geodetic mass balance calculation for the entire archipelago. We estimated its geodetic mass balance over a 3–4-year period within 2013–2017. Our estimation is based on remotely sensed multispectral and interferometric SAR data covering 96% of the glacierized areas of the islands considered in our study and 73% of the total glacierized area of the SSI archipelago (Elephant, Clarence, and Smith Islands were excluded due to data limitations). Our results show a close to balance, slightly negative average specific mass balance for the whole area of −0.106 ± 0.007 m w.e. a⁻¹, representing a mass change of −238 ± 12 Mt a⁻¹. These results are consistent with a wider scale geodetic mass balance estimation and with glaciological mass balance measurements at SSI locations for the same study period. They are also consistent with the cooling trend observed in the region between 1998 and the mid-2010s. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

16 pages, 6354 KiB

Open AccessArticle

Seasonal Surface Change of Urumqi Glacier No. 1, Eastern Tien Shan, China, Revealed by Repeated High-Resolution UAV Photogrammetry

by Puyu Wang, Hongliang Li, Zhongqin Li, Yushuo Liu, Chunhai Xu, Jianxin Mu and Hui Zhang

Remote Sens. 2021, 13(17), 3398; https://doi.org/10.3390/rs13173398 - 27 Aug 2021

Cited by 12 | Viewed by 3133

Abstract

The seasonal surface changes of glaciers in Tien Shan have seen little prior investigation despite the increase in geodetic studies of multi-year changes. In this study, we analyzed the potential of an Unmanned Aerial Vehicle (UAV) to analyze seasonal surface change processes of [...] Read more.

The seasonal surface changes of glaciers in Tien Shan have seen little prior investigation despite the increase in geodetic studies of multi-year changes. In this study, we analyzed the potential of an Unmanned Aerial Vehicle (UAV) to analyze seasonal surface change processes of the Urumqi Glacier No. 1 in eastern Tien Shan. We carried out UAV surveys at the beginning and the end of the ablation period in 2018. The high-precision evolution of surface elevation, geodetic mass changes, surface velocity, and terminus change in the surveyed ablation area were correspondingly derived in combination with ground measurements, including stake/snow-pit observation and GPS measurement. The derived mean elevation change in the surveyed ablation area was −1.64 m, corresponding to the geodetic mass balance of approximately −1.39 m w.e. during the ablation period in 2018. The mean surface velocity was 3.3 m/yr and characterized by the spatial change of the velocity, which was less in the East Branch than in the West Branch. The UAV survey results were a little less than those from the ground measurements, and the correlation coefficient was 0.88 for the surface elevation change and 0.87 for surface displacement. The relative error of the glacier terminus change was 4.5% for the East Branch and 6.2% for the West Branch. These results show that UAV photogrammetry is ideal for assessing seasonal glacier surface changes and has a potential application in the monitoring of detailed glacier changes. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

15 pages, 5915 KiB

Open AccessArticle

Snow Lapse Rate Changes in the Atlas Mountain in Morocco Based on MODIS Time Series during the Period 2000–2016

by Ahmed Marchane, Abdelghani Boudhar, Mohammed Wassim Baba, Lahoucine Hanich and Abdelghani Chehbouni

Remote Sens. 2021, 13(17), 3370; https://doi.org/10.3390/rs13173370 - 25 Aug 2021

Cited by 11 | Viewed by 2805

Abstract

The spatio-temporal distribution of snow cover metrics in a mountainous area is mainly related to the climatic conditions as well as to the prevailing morphological conditions. The present study aimed to investigate the altitudinal sensitivity of snow cover metrics using the MODIS Terra [...] Read more.

The spatio-temporal distribution of snow cover metrics in a mountainous area is mainly related to the climatic conditions as well as to the prevailing morphological conditions. The present study aimed to investigate the altitudinal sensitivity of snow cover metrics using the MODIS Terra snow cover product (MOD10A1 v5). Annual snow metrics, including start of snow season (SOSS), end of snow season (EOSS), and snow cover duration (SCD) were extracted from snow-covered area (SCA) maps, which had been pre-processed using a cloud removal algorithm; the maps were of the Atlas Mountains, taken from the period of 2001–2016. In addition, a linear regression was applied to derive an annual altitudinal gradient for each snow metric in relation to various spatial scales in order to analyze the interdependency between snow and topography, and especially to assess the potential temporal trend of the snow gradient. Results indicated that elevation was the principal regulator of snow presence where snow was mostly accumulated above 2500 m. The annual altitudinal gradients for EOSS and SCD showed a marked negative trend beginning in 2007. However, the SOSS altitudinal gradient was marked by a positive trend. The mean SCD gradient for the entire Atlas Mountains decreased from 6 days/100 m to 3 days/100 m. This is a new and important finding since it may indicate the impact of climate change on the dynamics of snow metrics and provides guidance for water managers to better manage the snowmelt water with different terrain features. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

15 pages, 10169 KiB

Open AccessArticle

High-Resolution Monitoring of Glacier Mass Balance and Dynamics with Unmanned Aerial Vehicles on the Ningchan No. 1 Glacier in the Qilian Mountains, China

by Bo Cao, Weijin Guan, Kaiji Li, Baotian Pan and Xiaodong Sun

Remote Sens. 2021, 13(14), 2735; https://doi.org/10.3390/rs13142735 - 12 Jul 2021

Cited by 15 | Viewed by 4254

Abstract

Glaciers located in the Qilian Mountains are rapidly retreating and thinning due to climate change. The current understanding of small glacier mass balance changes under a changing climate is limited by the scarcity of in situ measurements in both time and space as [...] Read more.

Glaciers located in the Qilian Mountains are rapidly retreating and thinning due to climate change. The current understanding of small glacier mass balance changes under a changing climate is limited by the scarcity of in situ measurements in both time and space as well as the resolution of remote sensing products. Unmanned aerial vehicles (UAVs) provide an unparalleled opportunity to track the spatiotemporal variations in glacier extent at a high resolution and the changing glacier morphological features related to glacial dynamics. Five measurements were performed on the Ningchan No. 1 (NC01) glacier in the Qilian Mountains between 18 August 2017 and 13 August 2020. The glacier changes displayed in the digital orthophoto maps (DOMs) and digital surface models (DSMs) show a 7.4 ± 0.1 m a⁻¹ retreat of the terminus of NC01, a mass balance of −1.22 ± 0.1 m w.e. a⁻¹ from 2017 to 2020, and a maximum surface velocity of 3.2 ± 0.47 m from 18 August 2017 to 26 August 2018, which clearly show consistency with stake measurements. The surface elevation change was influenced by the combined effects of air temperature, altitude, slope, and surface velocity. This research demonstrates that UAV photogrammetry can greatly improve the temporal and spatial resolution of glaciological research. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Figure 1

19 pages, 2987 KiB

Open AccessArticle

A Revised Snow Cover Algorithm to Improve Discrimination between Snow and Clouds: A Case Study in Gran Paradiso National Park

by Chiara Richiardi, Palma Blonda, Fabio Michele Rana, Mattia Santoro, Cristina Tarantino, Saverio Vicario and Maria Adamo

Remote Sens. 2021, 13(10), 1957; https://doi.org/10.3390/rs13101957 - 18 May 2021

Cited by 5 | Viewed by 4436

Abstract

Snow cover plays an important role in biotic and abiotic environmental processes, as well as human activities, on both regional and global scales. Due to the difficulty of in situ data collection in vast and inaccessible areas, the use of optical satellite imagery [...] Read more.

Snow cover plays an important role in biotic and abiotic environmental processes, as well as human activities, on both regional and global scales. Due to the difficulty of in situ data collection in vast and inaccessible areas, the use of optical satellite imagery represents a useful support for snow cover mapping. At present, several operational snow cover algorithms and products are available. Even though most of them offer an up-to-daily time scale, they do not provide sufficient spatial resolution for studies requiring high spatial detail. By contrast, the Let-It-Snow (LIS) algorithm can produce high-resolution snow cover maps, based on the use of both the normalized-difference snow index (NDSI) and a digital elevation model. The latter is introduced to define a threshold value on the altitude, below which the presence of snow is excluded. In this study, we revised the LIS algorithm by introducing a new parameter, based on a threshold in the shortwave infrared (SWIR) band, and by modifying the overall algorithm workflow, such that the cloud mask selection can be used as an input. The revised algorithm has been applied to a case study in Gran Paradiso National Park. Unlike previous studies, we also compared the performance of both the original and the modified algorithms in the presence of cloud cover, in order to evaluate their effectiveness in discriminating between snow and clouds. Ground data collected by meteorological stations equipped with both snow gauges and solarimeters were used for validation purposes. The changes introduced in the revised algorithm can improve upon the overall classification accuracy obtained by the original LIS algorithm (i.e., up to 89.17 from 80.88%). The producer’s and user’s accuracy values obtained by the modified algorithm (89.12 and 95.03%, respectively) were larger than those obtained by the original algorithm (76.68 and 93.67%, respectively), thus providing a more accurate snow cover map. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

19 pages, 4841 KiB

Open AccessArticle

Spatio-Temporal Changes of Mass Balance in the Ablation Area of the Muz Taw Glacier, Sawir Mountains, from Multi-Temporal Terrestrial Geodetic Surveys

by Chunhai Xu, Zhongqin Li, Feiteng Wang and Jianxin Mu

Remote Sens. 2021, 13(8), 1465; https://doi.org/10.3390/rs13081465 - 10 Apr 2021

Cited by 10 | Viewed by 2912

Abstract

The glaciers in the Sawir Mountains are an important freshwater resource, and glaciers have been experiencing a continuing retreat over the past few decades. However, studies on detailed glacier mass changes are currently sparse. Here, we present the high-precision evolution of annual surface [...] Read more.

The glaciers in the Sawir Mountains are an important freshwater resource, and glaciers have been experiencing a continuing retreat over the past few decades. However, studies on detailed glacier mass changes are currently sparse. Here, we present the high-precision evolution of annual surface elevation and geodetic mass changes in the ablation area of the Muz Taw Glacier (Sawir Mountains, China) over the latest three consecutive mass-balance years (2017–2020) based on multi-temporal terrestrial geodetic surveys. Our results revealed clearly surface lowering and negative geodetic mass changes, and the spatial changing patterns were generally similar for the three periods with the most negative surface lowering (approximately −5.0 to −4.0 m a⁻¹) around the glacier terminus. The gradient of altitudinal elevation changes was commonly steep at the low elevations and gentle in the upper-elevation parts, and reduced surface lowering was observed at the glacier terminus. Resulting emergence velocities ranged from 0.11 to 0.86 m a⁻¹ with pronounced spatial variability, which was mainly controlled by surface slope, ice thickness, and the movement of tributary glaciers. Meanwhile, emergence velocities slightly compensated the surface ablation at the ablation area with a proportion of 14.9%, and dynamic thickening had small contributions to glacier surface evolution. Limited annual precipitation and glacier accumulation may result in these weak contributions. Higher-resolution surveys at the seasonal and monthly scales are required to get insight into the mass balance processes and their mechanism. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

30 pages, 21631 KiB

Open AccessArticle

Variation in Ice Phenology of Large Lakes over the Northern Hemisphere Based on Passive Microwave Remote Sensing Data

by Lei Su, Tao Che and Liyun Dai

Remote Sens. 2021, 13(7), 1389; https://doi.org/10.3390/rs13071389 - 4 Apr 2021

Cited by 9 | Viewed by 3187

Abstract

Ice phenology data of 22 large lakes of the Northern Hemisphere for 40 years (1979–2018) have been retrieved from passive microwave remote sensing brightness temperature (Tb). The results were compared with site-observation data and visual interpretation from Moderate Resolution Imaging Spectroradiometer (MODIS) surface [...] Read more.

Ice phenology data of 22 large lakes of the Northern Hemisphere for 40 years (1979–2018) have been retrieved from passive microwave remote sensing brightness temperature (Tb). The results were compared with site-observation data and visual interpretation from Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectivity products images (MOD09GA). The mean absolute errors of four lake ice phenology parameters, including freeze-up start date (FUS), freeze-up end date (FUE), break-up start date (BUS), and break-up end date (BUE) against MODIS-derived ice phenology were 2.50, 2.33, 1.98, and 3.27 days, respectively. The long-term variation in lake ice phenology indicates that FUS and FUE are delayed; BUS and BUE are earlier; ice duration (ID) and complete ice duration (CID) have a general decreasing trend. The average change rates of FUS, FUE, BUS, BUE, ID, and CID of lakes in this study from 1979 to 2018 were 0.23, 0.23, −0.17, −0.33, −0.67, and −0.48 days/year, respectively. Air temperature and latitude are two dominant driving factors of lake ice phenology. Lake ice phenology for the period 2021–2100 was predicted by the relationship between ice phenology and air temperature for each lake. Compared with lake ice phenology changes from 1990 to 2010, FUS is projected to be delayed by 3.1 days and 11.8 days under Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios, respectively; BUS is projected to be earlier by 3.3 days and 10.7 days, respectively; and ice duration from 2080 to 2100 will decrease by 6.5 days and 21.9 days, respectively. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

Other

Jump to: Research

20 pages, 18707 KiB

Open AccessTechnical Note

Attention Multi-Scale Network for Automatic Layer Extraction of Ice Radar Topological Sequences

by Yiheng Cai, Dan Liu, Jin Xie, Jingxian Yang, Xiangbin Cui and Shinan Lang

Remote Sens. 2021, 13(12), 2425; https://doi.org/10.3390/rs13122425 - 21 Jun 2021

Cited by 1 | Viewed by 2417

Abstract

Analyzing the surface and bedrock locations in radar imagery enables the computation of ice sheet thickness, which is important for the study of ice sheets, their volume and how they may contribute to global climate change. However, the traditional handcrafted methods cannot quickly [...] Read more.

Analyzing the surface and bedrock locations in radar imagery enables the computation of ice sheet thickness, which is important for the study of ice sheets, their volume and how they may contribute to global climate change. However, the traditional handcrafted methods cannot quickly provide quantitative, objective and reliable extraction of information from radargrams. Most traditional handcrafted methods, designed to detect ice-surface and ice-bed layers from ice sheet radargrams, require complex human involvement and are difficult to apply to large datasets, while deep learning methods can obtain better results in a generalized way. In this study, an end-to-end multi-scale attention network (MsANet) is proposed to realize the estimation and reconstruction of layers in sequences of ice sheet radar tomographic images. First, we use an improved 3D convolutional network, C3D-M, whose first full connection layer is replaced by a convolution unit to better maintain the spatial relativity of ice layer features, as the backbone. Then, an adjustable multi-scale module uses different scale filters to learn scale information to enhance the feature extraction capabilities of the network. Finally, an attention module extended to 3D space removes a redundant bottleneck unit to better fuse and refine ice layer features. Radar sequential images collected by the Center of Remote Sensing of Ice Sheets in 2014 are used as training and testing data. Compared with state-of-the-art deep learning methods, the MsANet shows a 10% reduction (2.14 pixels) on the measurement of average mean absolute column-wise error for detecting the ice-surface and ice-bottom layers, runs faster and uses approximately 12 million fewer parameters. Full article

(This article belongs to the Special Issue The Cryosphere Observations Based on Using Remote Sensing Techniques)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

The Cryosphere Observations Based on Using Remote Sensing Techniques

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Related Special Issue

Published Papers (19 papers)

Research

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI