scholarly journals Snow accumulation of a high alpine catchment derived from LiDAR measurements

2012 ◽  
Vol 32 ◽  
pp. 31-39 ◽  
Author(s):  
K. Helfricht ◽  
J. Schöber ◽  
B. Seiser ◽  
A. Fischer ◽  
J. Stötter ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Snow Accumulation ◽  
Airborne Lidar ◽  
Surface Elevation ◽  
High Mountain ◽  
Runoff Generation ◽  
Spatial Characteristics ◽  
Simple Regression Model ◽  
Lidar Measurements ◽  
Elevation Changes

Abstract. The spatial distribution of snow accumulation substantially affects the seasonal course of water storage and runoff generation in high mountain catchments. Whereas the areal extent of snow cover can be recorded by satellite data, spatial distribution of snow depth and hence snow water equivalent (SWE) is difficult to measure on catchment scale. In this study we present the application of airborne LiDAR (Light Detecting And Ranging) data to extract snow depths and accumulation distribution in an alpine catchment. Airborne LiDAR measurements were performed in a glacierized catchment in the Ötztal Alps at the beginning and the end of three accumulation seasons. The resulting digital elevation models (DEMs) were used to calculate surface elevation changes throughout the winter season. These surface elevation changes were primarily referred to as snow depths and are discussed concerning measured precipitation and the spatial characteristics of the accumulation distribution in glacierized and unglacierized areas. To determine the redistribution of catchment precipitation, snow depths were converted into SWE using a simple regression model. Snow accumulation gradients and snow redistribution were evaluated for 100 m elevation bands. Mean surface elevation changes of the whole catchment ranges from 1.97 m to 2.65 m within the analyzed accumulation seasons. By analyzing the distribution of the snow depths, elevation dependent patterns were obtained as a function of the topography in terms of aspect and slope. The high resolution DEMs show clearly the higher variation of snow depths in rough unglacierized areas compared to snow depths on smooth glacier surfaces. Mean snow depths in glacierized areas are higher than in unglacierized areas. Maximum mean snow depths of 100 m elevation bands are found between 2900 m and 3000 m a.s.l. in unglacierized areas and between 2800 m and 2900 m a.s.l. in glacierized areas, respectively. Calculated accumulation gradients range from 8% to 13% per 100 m elevation band in the observed catchment. Elevation distribution of accumulation calculated by applying these seasonal gradients in comparison to elevation distribution of SWE obtained from airborne laser scanning (ALS) data show the total redistribution of snow from higher to lower elevation bands. Revealing both, information about the spatial distribution of snow depths and hence the volume of the snow pack, ALS data are an important source for extensive snow accumulation measurements in high alpine catchments. These information about the spatial characteristics of snow distribution are crucial for calibrating hydrological models in order to realistically compute temporal runoff generation by snow melt.

scholarly journals LiDAR snow cover studies on glacier surface: significance of snow- and ice dynamical processes

2013 ◽  
Vol 7 (2) ◽  
pp. 1787-1832 ◽  
Author(s):  
K. Helfricht ◽  
M. Kuhn ◽  
M. Keuschnig ◽  
A. Heilig
Keyword(s):  
Spatial Distribution ◽  
Standard Deviation ◽  
Snow Cover ◽  
Snow Depth ◽  
Laser Scanning ◽  
Snow Accumulation ◽  
Surface Elevation ◽  
High Mountain ◽  
Dynamical Processes ◽  
Elevation Changes

Abstract. The storage of water within the seasonal snow cover is a substantial source for runoff in high mountain catchments. Information about the spatial distribution of snow accumulation is necessary for calibration and validation of hydro-meteorological models. Generally only a small number of precipitation measurements deliver precipitation input for modeling in remote mountain areas. The spatial interpolation and extrapolation of measurements of precipitation is still difficult. Multi-temporal application of Light Detecting And Ranging (LiDAR) techniques from aircraft, so-called airborne laser scanning (ALS), enables to derive surface elevations changes even in inaccessible terrain. Within one snow accumulation season these surface elevation changes can be interpreted as snow depths as a first assumption for snow hydrological studies. However, dynamical processes in snow, firn and ice are contributing to surface elevation changes on glaciers. To evaluate the magnitude and significance of these processes on alpine glaciers in the present state, ALS derived surface elevation changes were compared to converted snow depths from 35.4 km of ground penetrating radar (GPR) profiles on four glaciers in the high alpine region of Ötztal Alps. LANDSAT data were used to distinguish between firn and ice areas of the glaciers. In firn areas submerging ice flow and densification of firn and snow are contributing to a mean relative deviation of ALS surface elevation changes from actually observed snow depths of −20.0% with a mean standard deviation of 17.1%. Deviations between ALS surface elevation changes and GPR snow depth are small along the profiles on the glacier tongues. At these areas mean absolute deviation of ALS surface elevation changes and GPR snow depth is 0.004 m with a mean standard deviation of 0.27 m. Emergence flow leads to distinct positive deviations only at the very front of the glacier tongues. Snow depths derived from ALS deviate less from actually measured snow depths than expected errors of in-situ measurements of solid precipitation. Hence, ALS derived snow depths are an important data source for both, spatial distribution and total sum of the snow cover volume stored on the investigated glaciers and in the corresponding high mountain catchments at the end of an accumulation season.

scholarly journals Lidar snow cover studies on glaciers in the Ötztal Alps (Austria): comparison with snow depths calculated from GPR measurements

2014 ◽  
Vol 8 (1) ◽  
pp. 41-57 ◽  
Author(s):  
K. Helfricht ◽  
M. Kuhn ◽  
M. Keuschnig ◽  
A. Heilig
Keyword(s):  
Spatial Distribution ◽  
Standard Deviation ◽  
Snow Cover ◽  
Snow Depth ◽  
Snow Accumulation ◽  
Surface Elevation ◽  
Absolute Difference ◽  
High Mountain ◽  
Depth Maps ◽  
Elevation Changes

Abstract. The storage of water within the seasonal snow cover is a substantial source of runoff in high mountain catchments. Information about the spatial distribution of snow accumulation is necessary for calibration and validation of hydro-meteorological models. Generally, only a small number of precipitation measurements deliver precipitation input for modelling in mountain areas. The spatial interpolation and extrapolation of measurements of precipitation is still difficult. Multi-temporal application of lidar techniques from aircraft, so-called airborne laser scanning (ALS), provides surface elevations changes even in inaccessible terrain. These ALS surface elevation changes can be used to derive changes in snow depths of the mountain snow cover for seasonal or subseasonal time periods. However, since glacier surfaces are not static over time, ablation, densification of snow, densification of firn and ice flow contribute to surface elevation changes. ALS-derived surface elevation changes were compared to snow depths derived from 35.4 km of ground penetrating radar (GPR) profiles on four glaciers. With this combination of two different data acquisitions, it is possible to evaluate the effect of the summation of these processes on ALS-derived snow depth maps in the high alpine region of the Ötztal Alps (Austria). A Landsat 5 Thematic Mapper image was used to distinguish between snow covered area and bare ice areas of the glaciers at the end of the ablation season. In typical accumulation areas, ALS surface elevation changes differ from snow depths calculated from GPR measurements by −0.4 m on average with a mean standard deviation of 0.34 m. Differences between ALS surface elevation changes and GPR derived snow depths are small along the profiles conducted in areas of bare ice. In these areas, the mean absolute difference of ALS surface elevation changes and GPR snow depths is 0.004 m with a standard deviation of 0.27 m. This study presents a systematic approach to analyze deviations from ALS generated snow depth maps to ground truth measurements on four different glaciers. We could show that ALS can be an important and reliable data source for the spatial distribution of snow depths for most parts of the here investigated glaciers. However, within accumulation areas, just utilizing ALS data may lead to systematic underestimation of total snow depth distribution.

Glacier surface elevation changes in Rongbuk Catchment of the Central Himalayas in the last four decades

2020 ◽  
Author(s):  
Qinghua Ye ◽  
Wei Nie ◽  
Yimin Chen ◽  
Gang Li ◽  
lide Tian ◽  
...  
Keyword(s):  
Climate Modeling ◽  
Melting Rate ◽  
Surface Elevation ◽  
High Mountain ◽  
Glacier Surface ◽  
Important Indicator ◽  
Central Himalayas ◽  
Glacier Melting ◽  
Elevation Changes ◽  
Thinning Rate

<p>Glaciers in the central Himalayas are important water resources for the downstream habitants, and accelerating melting of the high mountain glaciers speed up with continuous warming. We summerized the geodetic glacier surface elevation changes (Dh) by 6 data sets at different time periods during 1974-2016 in RongbukCatchment(RC) on the northern slope of Mt. Qomolangma (Mt. Everest) in the Central Himalayas. The result showed that glacier Dh varied with altitude and time, from -0.29 ± 0.03m a<sup>-1</sup> in 1974-2000, to -0.47 ±0.24 m a<sup>-1</sup> in 1974-2006,and -0.48 ±0.16 m a<sup>-1</sup> in 1974-2012. Dh increased to -0.60 ± 0.20 m a<sup>-1</sup> in 2000-2012, then decreased to-0.46 ± 0.24 m a<sup>-1</sup> in 2000-2014, and by -0.49 ± 0.08 m a<sup>-1</sup> in 2000-2016, showing a diverse rate being up - down- a little up. However, it generally presented a similar glacier thinning rate by -0.46~-0.49 m a<sup>-1</sup> in the last four decades since 1970s in RC according to Dh<sub>1974-2006</sub>, Dh<sub>1974-2012</sub>, Dh<sub>2000-2014</sub>, and Dh<sub>2000-2016</sub>. Local meteorological observations revealed that, to a first order, the glacier thinning rate was kept the same pace with the number of annual melting days (MD). In spite of the obviously arising summer air temperature (T<sub>S</sub>) in 2000-2014, a slowdown glacier melting rate by -391 mm w.e.a<sup>-1</sup> occurred in 2000-2014 because of less melting days with more precipitation and less annual mean temperature(T<sub>m</sub>). It shows that MD is another important indicator and controlling factor to evaluate or to estimate glacier melting trend, especially in hydrological or climate modeling.</p>

scholarly journals Airborne lidar measurements of aerosol spatial distribution and optical properties over the Atlantic Ocean during a European pollution outbreak of ACE-2

Tellus B ◽  
2000 ◽  
Vol 52 (2) ◽  
pp. 662-677 ◽  
Author(s):  
Cyrille Flamant ◽  
Jacques Pelon ◽  
Patrick Chazette ◽  
Vincent Trouillet ◽  
Patricia K. Quinn ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spatial Distribution ◽  
Atlantic Ocean ◽  
Airborne Lidar ◽  
Lidar Measurements

Occurrence and characteristics of ice-debris landforms in Poiqu basin (central Himalaya)

2020 ◽  
Author(s):  
Tobias Bolch ◽  
Philipp Rastner ◽  
Jan Bouke Pronk ◽  
Atanu Bhattacharya ◽  
Lin Liu ◽  
...  
Keyword(s):  
Surface Elevation ◽  
High Mountain ◽  
Central Himalaya ◽  
Digital Elevation ◽  
Debris Transport ◽  
Elevation Changes ◽  
Movement Field ◽  
Rock Glaciers ◽  
Southern Tibetan Plateau ◽  
Satellite Radar

<p>Rock glaciers and other ice-debris landforms (I-DLs) are an important part of the debris-transport system in high mountains and their internal ice could provide a relevant contribution to water supply especially in dry regions. Recent research has shown that I-DLs are abundant in High Mountain Asia, but knowledge about their occurrence and characteristics is still limited.</p><p>We are therefore investigating I-DLs in the Poiqu basin (~28°17´N, 85°58´E) – central Himalaya/southern Tibetan Plateau using remote sensing aided by field observations. We use very high-resolution stereo Pleiades data from the contemporary period and stereo Corona and Hexagon data from the 1970s to generate digital elevation models, applied satellite radar interferometry based on ALOS-1 PALSAR and Sentinel-1 SAR data and feature tracking using Sentinel-2 and the Pleiades data. Generated DEMs allowed us to create a hillshade to support identification, to derive their topographical parameters and to investigate surface elevation changes. I-DLs were identified and classified based on their characteristic shape, their surface structure and surface movement. Field observationssupported the identification of the landforms.</p><p>We found abundant occurrence of rock glaciers (with typical characteristics like lobate-shaped forms, ridges and furrows as well as steep fronts) but also significant movements of both former lateral moraines and debris-slopes in permafrost area. Preliminary results revealed the occurrence of more than 350 rock glaciers covering an area of about 21 km<sup>2</sup>. About 150 of them are active. The largest rock glacier has an area of 0.5 km<sup>2</sup> and three have an area of more than 0.3 km<sup>2</sup>. The rock glaciers are located between ~3715 m and ~5850 m with a mean altitude of ~5075 m a.s.l.. The mean slope of all rock glaciers is close to 17.5° (min. 6.8°, max. 37.6°). Most of the rock glaciers face towards the Northeast (19%) and West (18.5%). Surface elevation changes between the 1970s and 2018 show no significant changes but indicate slight elevation gain at the front of active rock glaciers caused by their downward movements.</p><p>Work will be continued to generate an inventory of all I-DLs in the study area including information about their activity and surface elevation changes.</p>

scholarly journals Recent volume and area changes of Kaskawulsh Glacier, Yukon, Canada

2011 ◽  
Vol 57 (203) ◽  
pp. 515-525 ◽  
Author(s):  
Norah Foy ◽  
Luke Copland ◽  
Christian Zdanowicz ◽  
Mike Demuth ◽  
Chris Hopkinson
Keyword(s):  
Satellite Imagery ◽  
Volume Change ◽  
Aerial Photography ◽  
Airborne Lidar ◽  
Ablation Zone ◽  
Constant Rate ◽  
Lidar Measurements ◽  
Historical Aerial Photography ◽  
Elevation Changes ◽  
Air Photo

AbstractRecent surface elevation changes of Kaskawulsh Glacier, Yukon, Canada, are quantified by comparing an air-photo derived DEM from 1977 and airborne lidar measurements from 1995, 2000 and 2007. Surface-area changes are assessed using historical aerial photography from 1956 and satellite imagery from 1977 to 2007. Combined, these measurements provide some of the first detailed records of volume change of a large Yukon glacier. Between 1977 and 2007, Kaskawulsh Glacier underwent a decrease in area of 1.53% and a decrease in volume of 3.27–5.94 km3 w.e.). The terminus also retreated by 655 m over the period 1956–2007. There was relatively minor volume change over the period 1977–95 (<+0.01 km3 w.e.a−1), while over the periods 1995–2000 and 2000–07 volume losses occurred at a relatively constant rate of −0.51 and −0.50 km3 a−1 w.e., respectively. Since 1995, thinning has been prominent throughout the ablation zone, while relative stability and even slight thickening has occurred in the accumulation zone. These findings are similar to those recently observed at other nearby Alaskan glaciers.

scholarly journals Airborne lidar measurements of aerosol spatial distribution and optical properties over the Atlantic Ocean during a European pollution outbreak of ACE-2

Tellus B ◽  
2000 ◽  
Vol 52 (2) ◽  
pp. 662-677 ◽  
Author(s):  
Cyrille Flamant ◽  
Jacques Pelon ◽  
Patrick Chazette ◽  
Vincent Trouillet ◽  
Patricia K. Quinn ◽  
...  
Keyword(s):  
Optical Properties ◽  
Spatial Distribution ◽  
Atlantic Ocean ◽  
Airborne Lidar ◽  
Lidar Measurements

scholarly journals No significant mass loss in the glaciers of Astore Basin (North-Western Himalaya), between 1999 and 2016

2019 ◽  
Vol 65 (250) ◽  
pp. 270-278 ◽  
Author(s):  
SHER MUHAMMAD ◽  
LIDE TIAN ◽  
MARCUS NÜSSER
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Thermal Emission ◽  
Western Himalaya ◽  
Surface Elevation ◽  
High Mountain ◽  
Differential Gps ◽  
Average Mass ◽  
Elevation Changes ◽  
Geodetic Mass Balance

ABSTRACTAlthough glaciers in High Mountain Asia produce an enormous amount of water used by downstream populations, they remain poorly observed in the field. This study presents a geodetic mass balance of the glaciers in the Astore Basin (with differential GPS (dGPS) measurements on Harcho glacier) between 1999 and 2016. Changes near the terminus of Harcho glacier (below 3800 m a.s.l.) featured heterogeneous surface elevation changes, whereas the middle section shows the most negative changes. The surface elevation changes were positive above 4200 m a.s.l. The average annual mass balance was −0.08 ± 0.07 m w.e. a−1 derived from a dGPS and DEM comparison whereas Advanced Spaceborne Thermal Emission and Reflection Radiometer DEM-based results show a slightly positive, that is 0.03 ± 0.24 m w.e. a−1 in the same period. In contrast, the terminus indicates a substantial retreat of ~368 m (4.5 m a−1) between 1934 and 2016. The average mass balance of 19 glaciers (>2 km2) covering ~60% of the total glaciers in the Basin exhibit no net mass loss in the period of 2000−2016 and follow a pattern similar to adjacent Karakoram glaciers.

scholarly journals Application and Validation of a Model for Terrain Slope Estimation Using Space-Borne LiDAR Waveform Data

2018 ◽  
Vol 10 (11) ◽  
pp. 1691 ◽  
Author(s):  
Xuebo Yang ◽  
Cheng Wang ◽  
Sheng Nie ◽  
Xiaohuan Xi ◽  
Zhenyue Hu ◽  
...  
Keyword(s):  
Surface Characteristics ◽  
Airborne Lidar ◽  
Estimation Accuracy ◽  
Estimation Model ◽  
Large Area ◽  
Waveform Data ◽  
Terrain Slope ◽  
Lidar Measurements ◽  
Slope Estimation ◽  
Study Sites

The terrain slope is one of the most important surface characteristics for quantifying the Earth surface processes. Space-borne LiDAR sensors have produced high-accuracy and large-area terrain measurement within the footprint. However, rigorous procedures are required to accurately estimate the terrain slope especially within the large footprint since the estimated slope is likely affected by footprint size, shape, orientation, and terrain aspect. Therefore, based on multiple available datasets, we explored the performance of a proposed terrain slope estimation model over several study sites and various footprint shapes. The terrain slopes were derived from the ICESAT/GLAS waveform data by the proposed method and five other methods in this study. Compared with five other methods, the proposed method considered the influence of footprint shape, orientation, and terrain aspect on the terrain slope estimation. Validation against the airborne LiDAR measurements showed that the proposed method performed better than five other methods (R2 = 0.829, increased by ~0.07, RMSE = 3.596°, reduced by ~0.6°, n = 858). In addition, more statistics indicated that the proposed method significantly improved the terrain slope estimation accuracy in high-relief region (RMSE = 5.180°, reduced by ~1.8°, n = 218) or in the footprint with a great eccentricity (RMSE = 3.421°, reduced by ~1.1°, n = 313). Therefore, from these experiments, we concluded that this terrain slope estimation approach was beneficial for different terrains and various footprint shapes in practice and the improvement of estimated accuracy was distinctly related with the terrain slope and footprint eccentricity.

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