scholarly journals Southwest-facing slopes control the formation of debris-covered glaciers in the Bhutan Himalaya

2013 ◽  
Vol 7 (4) ◽  
pp. 1303-1314 ◽  
Author(s):  
H. Nagai ◽  
K. Fujita ◽  
T. Nuimura ◽  
A. Sakai
Keyword(s):  
Satellite Images ◽  
Important Variable ◽  
Permafrost Degradation ◽  
Freeze Thaw ◽  
The North ◽  
Covered Area ◽  
Debris Cover ◽  
Local Topography ◽  
Formation Conditions ◽  
Geographic Setting

Abstract. To understand the formation conditions of debris-covered glaciers, we examined the dimension and shape of debris-covered areas and potential debris-supply (PDS) slopes of 213 glaciers in the Bhutan Himalaya. This was undertaken using satellite images with 2.5 m spatial resolution for manual delineation of debris-covered areas and PDS slopes. The most significant correlation exists between surface area of southwest-facing PDS slopes and debris-covered area. This result suggests that the southwest-facing PDS slopes supply the largest quantity of debris mantle. The shape of debris-covered areas is also an important variable, quantitatively defined using a geometric index. Elongate or stripe-like debris-covered areas on north-flowing glaciers are common throughout the Bhutan Himalaya. In contrast, south-flowing glaciers have large ablation zones, entirely covered by debris. Our findings suggest that this difference is caused by effective diurnal freeze–thaw cycles rather than seasonal freeze–thaw cycles, permafrost degradation, or snow avalanches. In terms of geographic setting, local topography also contributes to glacier debris supply and the proportion of debris cover on the studied glaciers is suppressed by the arid Tibetan climate, whereas the north-to-south asymmetric topography of the Bhutan Himalaya has less influence on the proportion of debris cover.

scholarly journals Southwest-facing slopes control the formation of debris-covered glaciers in the Bhutan Himalaya

2013 ◽  
Vol 7 (2) ◽  
pp. 1673-1705
Author(s):  
H. Nagai ◽  
K. Fujita ◽  
T. Nuimura ◽  
A. Sakai
Keyword(s):  
Satellite Images ◽  
Important Variable ◽  
Permafrost Degradation ◽  
Freeze Thaw ◽  
The North ◽  
Covered Area ◽  
Debris Cover ◽  
Local Topography ◽  
Formation Conditions ◽  
Geographic Setting

Abstract. To understand the formation conditions of debris-covered glaciers, we examined the dimension and shape of debris-covered areas and potential debris-supply (PDS) slopes of 208 glaciers in the Bhutan Himalaya. This was undertaken using satellite images with 2.5 m spatial resolution for manual delineation of debris-covered areas and PDS slopes. The most significant correlation exists between surface area of southwest-facing PDS slopes and debris-covered area. This result suggests that the southwest-facing PDS slopes supply the largest quantity of debris mantle. The shape of debris-covered areas is also an important variable quantitatively defined using a geometric index. Elongate or stripe-like debris-covered areas on north-flowing glaciers are common throughout the Bhutan Himalaya, associated with the small quantities of debris from north-facing PDS slopes. In contrast, south-flowing glaciers have large ablation zones, entirely covered by debris. Our findings suggest that this difference is caused by effective diurnal freeze–thaw cycles rather than seasonal freeze–thaw cycles, permafrost degradation, or snow avalanches. In terms of geographic setting, local topography also contributes to glacier debris supply and the proportion of debris cover on the studied glaciers is suppressed by the arid Tibetan climate, whereas the north-to-south asymmetric topography of the Bhutan Himalaya has less influence on the proportion of debris cover.

scholarly journals Applications of Satellite Thermal Infrared Images for Monitoring North Water during the Periods of Polar Darkness

1980 ◽  
Vol 25 (93) ◽  
pp. 425-438
Author(s):  
B. Dey
Keyword(s):  
Satellite Images ◽  
Open Water ◽  
Thermal Infrared ◽  
Water Area ◽  
Infrared Images ◽  
Baffin Bay ◽  
The North ◽  
Thermal Infrared Images ◽  
North Water

AbstractThe study reported here illustrates the unique value of NOAA thermal infrared (TIR) images for monitoring the North Water area in Smith Sound and northern Baffin Bay during the periods of polar darkness. Wintertime satellite images reveal that, during the months of December through February, open water and thin ice occur in a few leads and polynyas. However, in March, the areas of open water and thin ice decrease to a minimum with a consequent higher concentration of ice. Two ice dams, in northern Kennedy Channel and in northern Smith Sound, regulate the flow of ice into northern Baffin Bay and also determine the areal variations of open water and thin ice in Smith Sound.

scholarly journals Glacial debris cover and melt water production for glaciers in the Altay, Russia

2011 ◽  
Vol 5 (1) ◽  
pp. 401-430 ◽  
Author(s):  
C. Mayer ◽  
A. Lambrecht ◽  
W. Hagg ◽  
Y. Narozhny
Keyword(s):  
Ice Melt ◽  
The North ◽  
Altay Mountains ◽  
Digital Elevation ◽  
Glacier Runoff ◽  
Debris Cover ◽  
Continuous Mass ◽  
Different Depths ◽  
The 1960S ◽  
Elevation Model

Abstract. Glaciers are important water storages on a seasonal and long-term time scale. Where high mountains are surrounded by arid lowlands, glacier runoff is an important source of water during the growing season. This situation can be found in the Altay mountains in Southern Siberia, where the recent glacierization of >700 km2 is subject to continuous mass loss, even though the shrinking is comparably slow. The glacier retreat is accompanied by an extension of supra-glacial moraine, which itself strongly influences ablation rates. To quantify these effects, the spatial evolution of debris cover since 1952 was analysed for three glaciers in the North Chuya Ridge using satellite and airborne imagery. In summer 2007, an ablation experiment was carried out on debris covered parts of Maliy Aktru glacier. Thermistors in different depths within the moraine provided data to calculate thermal resistance of the debris. A set of ablation stakes was installed at locations with differing debris thickness and observed regularly throughout the entire melt season. Air temperature from an AWS was used to calculate degree day factors in dependence of the debris thickness. To take into account the shading effect of surrounding walls and peaks, the potential solar radiation and its evolution throughout the summer was determined from a digital elevation model. This allows us to extrapolate our measurements from Maliy Aktru to the other two glaciers of the Aktru basin and to estimate basin melt rates. In addition accumulated ice melt was derived for 12 glaciers in the North Chuya Range. Changes in summer runoff from the 1960s are compared to the results from our melt model and the evolution of debris cover is analysed in respect to the melt activity.

scholarly journals Aufeis of the Indigirka river basin (Russia): the database from historical data and recent Landsat images

2018 ◽  
Author(s):  
Olga Makarieva ◽  
Andrey Shikhov ◽  
Nataliia Nesterova ◽  
Andrey Ostashov
Keyword(s):  
Interannual Variability ◽  
20Th Century ◽  
Historical Data ◽  
Topographic Maps ◽  
Landsat Images ◽  
North East ◽  
The North ◽  
Digital Database ◽  
Formation Conditions ◽  
Basin Area

Abstract. Detailed spatial geodatabase of aufeis in the Indigirka River, the basin area 305 000 km2, Russia was compiled from the Cadaster of aufeis of the North-East of the USSR published in 1958, topographic maps and Landsat images for 2013–2017. The aufeis area share varies from 0.26 to 1.15 % in different river sub-basins within the studied area. Digitized Cadaster (1958) contains the coordinates and characteristics of 897 aufeises with total area of 2064 km2. The Landsat-based identification of aufeises for 2013–2017 allowed the description of 1213 aufeises on a total area of 128 km2. The combined digital database of the aufeis is available at https://doi.pangaea.de/10.1594/PANGAEA.891036. The satellite-derived total area of aufeis is 1.6 times less than in the Cadaster (1958). At the same time, more than 600 aufeis identified by Landsat images analyses are missing in the Cadaster (1958). It implies that the aufeis formation conditions may have been changed between the mid-20th century and the present. About 60 % of total area presents 10 % of the largest aufeis. Most aufeis are located in the elevation band of 1100–1300 m. The interannual variability of the aufeis area was estimated by the example of the Bolshaya Momskaya naled (aufeis) and the group of large aufeis in the basin of the Syuryuktyakh River for the period of 2001–2016. The results of analysis indicate a tendency towards a decrease in the area of the Bolshaya Momskaya naled in recent years, at the same time the reduction in the aufeis area in the basin of the Syuryuktyakh River has not occurred.

Cryogenic cave carbonate formation during the Industrial Era in the Central Pyrenees (Iberian Peninsula)

2021 ◽  
Author(s):  
Miguel Bartolomé ◽  
Ana Moreno ◽  
Marc Luetscher ◽  
Christoph Spötl ◽  
Maria Leunda ◽  
...  
Keyword(s):  
Spring Water ◽  
Ice Formation ◽  
Cumulative Probability ◽  
Temperature Record ◽  
Permafrost Degradation ◽  
The North ◽  
Carbonate Formation ◽  
Discontinuous Permafrost ◽  
Ice Retreat ◽  
Instrumental Temperature

<p>Cryogenic cave carbonates (CCC) are rare speleothems that form when water freezes inside cave ice bodies. CCC have been used as an proxy for permafrost degradation, permafrost thickness, or subsurface ice formation. The presence of these minerals is usually attributed to warm periods of permafrost degradation. We found coarse crystalline CCC types within transparent, massive congelation ice in two Pyrenean ice caves in the Monte Perido Massif: Devaux, located on the north face at 2828 m a.s.l., and Sarrios 6, located in the south face at 2780 m a.s.l. The external mean annual air temperature (MAAT) at Devaux is ~ 0°C, while at Sarrios 6 is ~ 2.5°C. In the Monte Perdido massif discontinuous permafrost is currently present between 2750 and 2900 m a.s.l. and is more frequent above 2900 m a.s.l. in northern faces. In Devaux, air and rock temperatures, as well as the presence of hoarfrost and the absence of drip sites indicate a frozen host rock. Moreover, a river flows along the main gallery, and during winters the water freezes at the spring causing backflooding in the cave. In contrast, Sarrios 6 has several drip sites, although the gallery where CCC were collected is hydrologically inactive. This gallery opened in recent years due to ice retreat. During spring, water is present in the gallery due to the overflow of ponds forming beneath drips. CCC commonly formed as sub-millimeter-size spherulites, rhombohedrons and rafts. <sup>230</sup>Th ages of the same CCC morphotype indicate that their formation took place at 1953±7, 1959±14, 1957±14, 1958±15, 1974±16 CE in Devaux, while in Sarrios 6 they formed at 1964±5, 1992±2, 1996±1 CE. The cumulative probability density function indicates that the most probable formation occurred 1957-1965 and 1992-1997. The instrumental temperature record at 2860 m a.s.l. indicates positive MAAT in 1964 (0.2°C) and 1997 (0.8°C). CCC formation could thus correspond with those two anomalously warm years. The massive and transparent ice would indicate a sudden ingress of water and subsequent slow freezing inside both caves during those years. Probably, CCC formation took place at a seasonal scale during the annual cycle.</p>

scholarly journals Supra-glacial debris cover changes in the Greater Caucasus from 1986 to 2014

2020 ◽  
Vol 14 (2) ◽  
pp. 585-598 ◽  
Author(s):  
Levan G. Tielidze ◽  
Tobias Bolch ◽  
Roger D. Wheate ◽  
Stanislav S. Kutuzov ◽  
Ivan I. Lavrentiev ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Google Earth ◽  
Gps Data ◽  
Glacier Area ◽  
Greater Caucasus ◽  
Abstract Knowledge ◽  
Covered Area ◽  
Debris Cover ◽  
Automated Methods

Abstract. Knowledge of supra-glacial debris cover and its changes remain incomplete in the Greater Caucasus, in spite of recent glacier studies. Here we present data of supra-glacial debris cover for 659 glaciers across the Greater Caucasus based on Landsat and SPOT images from the years 1986, 2000 and 2014. We combined semi-automated methods for mapping the clean ice with manual digitization of debris-covered glacier parts and calculated supra-glacial debris-covered area as the residual between these two maps. The accuracy of the results was assessed by using high-resolution Google Earth imagery and GPS data for selected glaciers. From 1986 to 2014, the total glacier area decreased from 691.5±29.0 to 590.0±25.8 km2 (15.8±4.1 %, or ∼0.52 % yr−1), while the clean-ice area reduced from 643.2±25.9 to 511.0±20.9 km2 (20.1±4.0 %, or ∼0.73 % yr−1). In contrast supra-glacial debris cover increased from 7.0±6.4 %, or 48.3±3.1 km2, in 1986 to 13.4±6.2 % (∼0.22 % yr−1), or 79.0±4.9 km2, in 2014. Debris-free glaciers exhibited higher area and length reductions than debris-covered glaciers. The distribution of the supra-glacial debris cover differs between the northern and southern and between the western, central and eastern Greater Caucasus. The observed increase in supra-glacial debris cover is significantly stronger on the northern slopes. Overall, we have observed up-glacier average migration of supra-glacial debris cover from about 3015 to 3130 m a.s.l. (metres above sea level) during the investigated period.

scholarly journals Observations on the May 2019 Joffre Peak landslides, British Columbia

Landslides ◽  
2020 ◽  
Vol 17 (4) ◽  
pp. 913-930 ◽  
Author(s):  
Pierre Friele ◽  
Tom H. Millard ◽  
Andrew Mitchell ◽  
Kate E. Allstadt ◽  
Brian Menounos ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Seismic Analysis ◽  
Rock Avalanche ◽  
Permafrost Degradation ◽  
Depth Estimate ◽  
Coast Mountains ◽  
Conditioning Factors ◽  
The North ◽  
Debris Flood

AbstractTwo catastrophic landslides occurred in quick succession on 13 and 16 May 2019, from the north face of Joffre Peak, Cerise Creek, southern Coast Mountains, British Columbia. With headscarps at 2560 m and 2690 m elevation, both began as rock avalanches, rapidly transforming into debris flows along middle Cerise Creek, and finally into debris floods affecting the fan. Beyond the fan margin, a flood surge on Cayoosh Creek reached bankfull and attenuated rapidly downstream; only fine sediment reached Duffey Lake. The toe of the main debris flow deposit reached 4 km from the headscarp, with a travel angle of 0.28, while the debris flood phase reached the fan margin 5.9 km downstream, with a travel angle of 0.22. Photogrammetry indicates the source volume of each event is 2–3 Mm3, with combined volume of 5 Mm3. Lidar differencing, used to assess deposit volume, yielded a similar total result, although error in the depth estimate introduced large volume error masking the expected increase due to dilation and entrainment. The average velocity of the rock avalanche-debris flow phases, from seismic analysis, was ~ 25–30 m/s, and the velocity of the 16 May debris flood on the upper fan, from super-elevation and boulder sizes, was 5–10 m/s. The volume of debris deposited on the fan was ~ 104 m3, 2 orders of magnitude less than the avalanche/debris flow phases. Progressive glacier retreat and permafrost degradation were likely the conditioning factors; precursor rockfall activity was noted at least ~6 months previous; thus, the mountain was primed to fail. The 13 May landslide was apparently triggered by rapid snowmelt, with debuttressing triggering the 16 May event.

A New Species of Glenanthe Haliday (Diptera: Ephydridae) from the North American Interior

1964 ◽  
Vol 96 (5) ◽  
pp. 811-812 ◽  
Author(s):  
J. G. Chillcott
Keyword(s):  
New Species ◽  
North American ◽  
Sand Dunes ◽  
Wing Pattern ◽  
Lake Agassiz ◽  
The North ◽  
Covered Area ◽  
The One ◽  
A New Species

One of the most unusual results of intensive collecting in southern Manitoba in. 1958 was the discovery of this striking representative of a dominantly coastal genus of Ephydridae. It ivas collected at several times but in only the one locality, the Bald Head Hills, a region of active sand dunes in the largely stabilized, spruce-covered area representing the shores of the Pleistocene Lake Agassiz. The species is strikingly different from other species of the genus in its thoracic and wing pattern, hut in structural characters it is fairly typical.

Comparing streamflow analysis and remote sensing observations to assess climate change impact on permafrost degradation

2020 ◽  
Author(s):  
flore sergeant ◽  
rene therrien ◽  
ludovic oudin ◽  
anne jost ◽  
françois anctil
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Satellite Images ◽  
Ground Subsidence ◽  
Permafrost Degradation ◽  
Analysis Method ◽  
Temporal And Spatial ◽  
Thawing Rate ◽  
Permafrost Thawing

<p><strong>ABSTRACT</strong></p><p>Due to polar amplification of climate change, high latitudes are warming up twice as fast as the rest of the world. This warming leads to permafrost thawing, which induces greenhouse gases release, ground subsidence, and modifies surface and subsurface hydrologic regimes. Ground subsidence in turn affects local infrastructure stability. In this context and to better manage future infrastructures and water resources of northern regions, it is crucial to be able to evaluate the thawing rate of permafrost.</p><p>In many Arctic zones, the frequency of environmental disturbances caused by permafrost thawing increases so rapidly that maintaining an accurate inventory of the state of permafrost at a regional scale represents a great challenge. Moreover, depending on the study area and the permafrost ice content, the thawing rate can vary from millimetres to decimeters per year. Another current challenge is the limited availability of temporal and spatial data on permafrost thawing rates.</p><p>To address the above challenges, two indirect methods are used: (1) Arctic river streamflow analysis method and (2) Ground settlement analysis method via satellite image observation. Both methods use free-access data that have an exceptionally large temporal and spatial coverage capacity for such a poorly instrumented region. The first method analyses the recession events’ behavior of Arctic streams and relates those behaviors to changes in catchment-scale depth to permafrost that influences storage-discharge dynamics. This work differs from previous hydrological system analysis in northern systems in that it looks at long-term trends (>10 years) in recession intercept to assess permafrost dynamics, while other studies looked at recession characteristics within a season to assess active-layer dynamics. The second method analyses satellite images of the Arctic ground and associates surface elevation change to long-term permafrost degradation due to climate change.</p><p>Both methods have already been tested through multiple local investigations and gave promising results. The recession flow analysis method has been applied to Yukon river basin, northern Sweden basins and Lena basin in Siberia, while the remote sensing analysis method has been tested on Baffin Island, Herschel Island in Canada, North Slope of Alaska and the Tibetan Plateau. However, no comparative study and no large-scale application have been conducted so far. Extending the analysis to hundreds of Arctic basins and comparing the resulting permafrost-thawing rate values from both methods constitute the innovative aspect of this project.</p><p> </p><p>KEY WORDS: climate change, permafrost thawing, storage-discharge dynamics, ground subsidence, satellite images</p>

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