scholarly journals An ~1899 glacier inventory for Nordland, northern Norway, produced from historical maps

2020 ◽  
Vol 66 (256) ◽  
pp. 259-277 ◽  
Author(s):  
Paul Weber ◽  
Liss M. Andreassen ◽  
Clare M. Boston ◽  
Harold Lovell ◽  
Sidsel Kvarteig
Keyword(s):  
Ice Age ◽  
Aerial Photographs ◽  
Historical Maps ◽  
Glacier Inventory ◽  
Field Surveys ◽  
Northern Norway ◽  
Future Studies ◽  
Raster Graphics ◽  
Original Field ◽  
Written Descriptions

AbstractGlaciers depicted on old maps reveal their historical extents, before the advent of aerial and satellite remote sensing. Digital glacier inventories produced from these maps can be employed in assessments of centennial-scale glacier change. This study reconstructs the ~1899 (covering the period 1882–1916) glacier extent in Nordland, northern Norway, from historical gradteigskart maps, with an emphasis on examining the accuracy of the mapped glaciers. Glacier outlines were digitised from georectified scans of the analogue maps in a raster graphics editor and were subsequently inventoried in a GIS. The accuracy of the historical glacier extent was established from written descriptions and landscape photographs created during the original field surveys, and further validated against independent glacier outlines of (1) the maximum Little Ice Age extent derived from geomorphological evidence, and (2) the 1945 extent derived from vertical aerial photographs. An overall uncertainty of ±17% is associated with our inventory. Nordland's glaciers covered an area of 1712 ± 291 km2 in 1899. By 2000, total ice cover had decreased by 47% (807 ± 137 km2) at a rate of 6% 10 a−1 (80 ± 14 km2 10 a−1). The approach presented here may serve as a blueprint for future studies intending to derive glacier inventories from historical maps.

scholarly journals The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

1991 ◽  
Vol 37 (127) ◽  
pp. 388-400 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Gordon S. Hamilton ◽  
Jon Ove Hagen
Keyword(s):  
Time Series ◽  
North America ◽  
Active Phase ◽  
Aerial Photographs ◽  
Polar Ice ◽  
Phase Duration ◽  
Field Surveys ◽  
The World ◽  
Glacier Surges ◽  
Fast Motion

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

scholarly journals A new glacier inventory for the Svartisen region, Norway, from Landsat ETM+ data: challenges and change assessment

2009 ◽  
Vol 55 (192) ◽  
pp. 607-618 ◽  
Author(s):  
Frank Paul ◽  
Liss M. Andreassen
Keyword(s):  
Topographic Map ◽  
Large Area ◽  
Study Region ◽  
Glacier Inventory ◽  
Northern Norway ◽  
Change Assessment ◽  
Hydropower Production ◽  
Snow Conditions ◽  
Key Indicators ◽  
Glacier Mapping

AbstractGlaciers are widely recognized as key indicators of climate change, and their meltwater plays an important role in hydropower production in Norway. Since the last glacier inventory was compiled in northern Norway in the 1970s, marked fluctuations in glacier length and mass balance have been reported for individual glaciers, and the current overall glacier state is thus not well known. Within the framework of the Global Land Ice Measurements from Space (GLIMS) initiative, we have created a new inventory for 489 glaciers in the Svartisen region, northern Norway, using a Landsat Enhanced Thematic Mapper Plus (ETM+) satellite scene from 7 September 1999 and automated multispectral glacier mapping (thresholded band ratios). In addition, visual inspection and correction of the generated glacier outlines has been applied. Adverse snow conditions and uncertain drainage divides made glacier mapping challenging in some regions of the study site. Glacier outlines from 1968, as digitized from a topographic map, were used for a quantitative change assessment for a selection of 300 glaciers. The overall area change of this sample from 1968 to 1999 was close to zero, but with a strongly increasing scatter towards smaller glaciers, large area gains (>50%) for small glaciers (<1 km2), and an unexpected stronger relative area loss towards the wetter coast. The overall size changes are small (<1%) for the three largest ice masses in the study region (Vestisen, Østisen and Blåmannsisen).

scholarly journals A new glacier inventory on southern Baffin Island, Canada, from ASTER data: I. Applied methods, challenges and solutions

2009 ◽  
Vol 50 (53) ◽  
pp. 11-21 ◽  
Author(s):  
Felix Svoboda ◽  
Frank Paul
Keyword(s):  
Climate Change Impacts ◽  
Ice Age ◽  
Baffin Island ◽  
Glacier Inventory ◽  
Ice Caps ◽  
Digital Elevation ◽  
Glacier Length ◽  
Length And Area ◽  
Shortwave Infrared ◽  
Glacier Mapping

AbstractThe quantitative assessment of glacier changes as well as improved modeling of climate-change impacts on glaciers requires digital vector outlines of individual glacier entities. Unfortunately, such a glacier inventory is still lacking in many remote but extensively glacierized gions such as the Canadian Arctic. Multispectral satellite data in combination with digital elevation models (DEMs) a particularly useful for creating detailed glacier inventory data including topographic information for each entity. In this study, we extracted glacier outlines and a DEM using two adjacent Terra ASTER scenes acquired in August 2000 for a remote region on southern Baffin Island, Canada. Additionally, Little Ice Age (LIA) extents we digitized from trimlines and moraines visible on the ASTER scenes, and Landsat MSS and TM scenes from the years 1975 and 1990 we used to assess changes in glacier length and area. Because automated delineation of glaciers is based on a band in the shortwave infrared, we have developed a new semi-automated glacier-mapping approach for the MSS sensor. Wrongly classified debris-coved glaciers, water bodies and attached snowfields we corrected manually for both ASTER and MSS. Glacier drainage divides we manually digitized by combining visual interptation with DEM information. In this first paper, we describe the applied methods for glacier mapping and the glaciological challenges encounted (e.g. data voids, snow cover, ice caps, tributaries), while the second paper ports the data analyses and the derived changes.

Recent, rapid and profound changes to glacier morphology and dynamics, Juneau Icefield, Alaska

2021 ◽  
Author(s):  
Bethan Davies ◽  
Jacob Bendle ◽  
Robert McNabb ◽  
Jonathan Carrivick ◽  
Christopher McNeil ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Aerial Photographs ◽  
Equilibrium Line Altitude ◽  
Regional Warming ◽  
Geomorphological Mapping ◽  
Glacier Recession ◽  
Digital Elevation ◽  
High Resolution Satellite Imagery ◽  
Global Sea Level

&lt;p&gt;The Alaskan region (comprising glaciers in Alaska, British Columbia and Yukon) contains the third largest ice volume outside of the Greenland and Antarctic ice sheets, and contributes more to global sea level rise than any other glacierised region defined by the Randolph Glacier Inventory. However, ice loss in this area is not linear, but in part controlled by glacier hypsometry as valley and outlet glaciers are at risk of becoming detached from their accumulation areas during thinning. Plateau icefields, such as Juneau Icefield in Alaska, are very sensitive to changes in Equilibrium Line Altitude (ELA) as this can result in rapidly shrinking accumulation areas. Here, we present detailed geomorphological mapping around Juneau Icefield and use this data to reconstruct the icefield during the &amp;#8220;Little Ice Age&amp;#8221;. We use topographic maps, archival aerial photographs, high-resolution satellite imagery and digital elevation models to map glacier lake and glacier area and volume change from the Little Ice Age to the present day (1770, 1948, 1979, 1990, 2005, 2015 and 2019 AD). Structural glaciological mapping (1979 and 2019) highlights structural and topographic controls on non-linear glacier recession.&amp;#160; Our data shows pronounced glacier thinning and recession in response to widespread detachment of outlet glaciers from their plateau accumulation areas. Glacier detachments became common after 2005, and occurred with increasing frequency since then. Total summed rates of area change increased eightfold from 1770-1948 (-6.14 km&lt;sup&gt;2&lt;/sup&gt; a&lt;sup&gt;-1&lt;/sup&gt;) to 2015-2019 (-45.23 km&lt;sup&gt;2&lt;/sup&gt; a&lt;sup&gt;-1&lt;/sup&gt;). Total rates of recession were consistent from 1770 to 1990 AD, and grew increasingly rapid after 2005, in line with regional warming.&lt;/p&gt;

The new Swiss Glacier Inventory SGI2016: a detailed cartographic representation of Swiss glacier extent and supraglacial debris-cover

2021 ◽  
Author(s):  
Andreas Linsbauer ◽  
Matthias Huss ◽  
Elias Hodel ◽  
Andreas Bauder ◽  
Mauro Fischer ◽  
...  
Keyword(s):  
Surface Area ◽  
Swiss Alps ◽  
Aerial Images ◽  
Aerial Photographs ◽  
Slope Aspect ◽  
Relative Area ◽  
Glacier Surface ◽  
Glacier Inventory ◽  
Digital Elevation ◽  
Debris Cover

&lt;p&gt;With increasing anthropogenic greenhouse gas emissions and corresponding global warming, glaciers in Switzerland are shrinking rapidly as in many mountain ranges on Earth. Repeated glacier inventories are a key task to monitor such glacier changes and provide detailed information on the extent of glaciation, and important parameters such as area, elevation range, slope, aspect etc. for a given point or a period in time. Here we present the new Swiss Glacier Inventory (SGI2016) that has been acquired based on high-resolution aerial imagery and digital elevation models in cooperation with the Federal Office of Topography (swisstopo) and Glacier Monitoring in Switzerland (GLAMOS), bringing together topological and glaciological knowhow. We define the process, workflow and required glaciological adaptations to compile a highly accurate glacier inventory based on the digital Swiss topographic landscape model (swissTLM&lt;sup&gt;3D&lt;/sup&gt;).&lt;/p&gt;&lt;p&gt;The SGI2016 provides glacier outlines (areas), supraglacial debris cover, ice divides and location points of all glaciers in Switzerland referring to the years 2013-2018, whereas most of the glacier outlines have been mapped based on aerial images acquired between 2015-2017 (75% in number and 87% in area), with the centre year 2016. The SGI2016 maps 1400 individual glacier entities with a total glacier surface area of 961 km&lt;sup&gt;2&lt;/sup&gt; (whereof 11% / 104 km&lt;sup&gt;2&lt;/sup&gt; are debris-covered) and constitutes the so far most detailed cartographic representation of glacier extent in Switzerland. Analysing the dependencies between topographic parameters and debris-cover fraction on the basis of individual glaciers reveals that short glaciers with a moderate mean slope and glaciers with a low median elevation tend to have high debris fractions. A change assessment between the SGI1973 and SGI2016 based on individual glacier entities affirms the largest relative area changes for small glaciers and for low-elevation glaciers, whereas the largest glaciers show small relative area changes, though large absolute changes. The analysis further indicates a tendency for glaciers with a high share of supraglacial debris to show larger relative area changes.&lt;/p&gt;&lt;p&gt;Despite of an observed strong glacier volume loss between 2010 and 2016, the total glacier surface area of the SGI2016 is somewhat larger than reported in the last Swiss glacier inventory SGI2010. Even though both inventories were created based on swisstopo aerial photographs, the additional data, tools, resources and methodologies used by the professional cartographers digitizing glacier outlines in 3D for the SGI2016, are able to explain the counter-intuitive difference between SGI2010 and SGI2016. A direct comparison of these two datasets is thus not meaningful, but an experiment where a representative glacier sample of the SGI2010 was re-assessed based on the approaches of the SGI2016 led to an upscaled total glacier surface area of 1010 km&lt;sup&gt;2&lt;/sup&gt; for the Swiss Alps around 2010. This indicates an area loss of 49 km&lt;sup&gt;2&lt;/sup&gt; between the two last Swiss glacier inventories. As swisstopo data products are and will be regularly updated, the SGI2016 is the first step towards a consistent and accurate data product of repeated glacier inventories in six-year time intervals that promises a high comparability for individual glaciers and glacier samples.&lt;/p&gt;

scholarly journals Unravelling the evolution of Zmuttgletscher and its debris cover since the end of the Little Ice Age

2019 ◽  
Vol 13 (7) ◽  
pp. 1889-1909 ◽  
Author(s):  
Nico Mölg ◽  
Tobias Bolch ◽  
Andrea Walter ◽  
Andreas Vieli
Keyword(s):  
Mass Balance ◽  
Ice Age ◽  
Aerial Photographs ◽  
Dynamic Interactions ◽  
Glacier Surface ◽  
Ablation Area ◽  
Debris Cover ◽  
Historic Maps ◽  
Length And Area ◽  
Flow Velocities

Abstract. Debris-covered glaciers generally exhibit large, gently sloping, slow-flowing tongues. At present, many of these glaciers show high thinning rates despite thick debris cover. Due to the lack of observations, most existing studies have neglected the dynamic interactions between debris cover and glacier evolution over longer time periods. The main aim of this study is to reveal such interactions by reconstructing changes of debris cover, glacier geometry, flow velocities, and surface features of Zmuttgletscher (Switzerland), based on historic maps, satellite images, aerial photographs, and field observations. We show that debris cover extent has increased from ∼13 % to ∼32 % of the total glacier surface since 1859 and that in 2017 the debris is sufficiently thick to reduce ablation compared to bare ice over much of the ablation area. Despite the debris cover, the glacier-wide mass balance of Zmuttgletscher is comparable to that of debris-free glaciers located in similar settings, whereas changes in length and area have been small and delayed by comparison. Increased ice mass input in the 1970s and 1980s resulted in a temporary velocity increase, which led to a local decrease in debris cover extent, a lowering of the upper boundary of the ice-cliff zone, and a strong reduction in ice-cliff area, indicating a dynamic link between flow velocities, debris cover, and surface morphology. Since 2005, the lowermost 1.5 km of the glacier has been quasi-stagnant, despite a slight increase in the surface slope of the glacier tongue. We conclude that the long-term glacier-wide mass balance is mainly governed by climate. The debris cover governs the spatial pattern of elevation change without changing its glacier-wide magnitude, which we explain by the extended ablation area and the enhanced thinning in regions with thin debris further up-glacier and in areas with abundant meltwater channels and ice cliffs. At the same time rising temperatures lead to increasing debris cover and decreasing ice flux, thereby attenuating length and area losses.

scholarly journals Runoff processes and land use changes in the upper reaches of the Krupá river catchment during the last 70 years

2008 ◽  
Vol 2 (No. 3) ◽  
pp. 77-84
Author(s):  
R. Pavelková Chmelová ◽  
B. Šarapatka ◽  
M. Dumbrovský ◽  
P. Pavka
Keyword(s):  
Land Use ◽  
River Basin ◽  
Hydrological Model ◽  
Land Use Changes ◽  
Aerial Photographs ◽  
Historical Maps ◽  
River Catchment ◽  
Cadastral Maps ◽  
Left Tributary ◽  
Morava River

In this paper, the authors summarise the land use changes in the upper reaches of the Krup&aacute; river catchment, which is a left tributary of the Morava River. During last 70 years, the catchment was exposed to many important historical events that have been inscribed in the physique of the landscape in a very interesting way. The land use changes, which occurred during the last eight decades in the subcatchment of the Krup&aacute; river basin, have been analysed using historical maps, cadastral maps, and both historical and recent aerial photographs of the area. The next step is to estimate, through the CN method and DesQ hydrological model, how the runoff processes in the Krup&aacute; River catchment could be influenced by the land use changes.

scholarly journals Differential success in sampling of Atlantic Forest amphibians among different periods of the day

2015 ◽  
Vol 75 (2) ◽  
pp. 261-267 ◽  
Author(s):  
CFD. Rocha ◽  
CC. Siqueira ◽  
CV. Ariani ◽  
D. Vrcibradic ◽  
DM. Guedes ◽  
...  
Keyword(s):  
Large Scale ◽  
Atlantic Rainforest ◽  
Southeastern Brazil ◽  
Sampling Effort ◽  
Amphibian Species ◽  
Field Surveys ◽  
Future Studies ◽  
Pooled Data ◽  
Large Scale Field ◽  
Number Of Individuals

In general, anurans tend to be nocturnal, though diurnal activity is characteristic of some groups. Studies show that frog activity may be inferred based on the number of individuals collected at different periods of the day, during large-scale field surveys. We investigated the best period of the day to conduct amphibian sampling in nine Atlantic Rainforest areas in southeastern Brazil, based on intensive field surveys. At each locality we employed similar sampling effort during diurnal, crepuscular and nocturnal searches (totaling 704.5 sampling hours). We pooled data from all localities for each period and estimated the proportion of frogs of each species active at each period based on the total number of individuals and on the number of species found during all surveys for that period. We recorded a total of 817 individual frogs from 69 species. Species richness was highest at night (median = 12 species), intermediate at dusk (median = 8), and lowest during the day (median = 4). The percentage of the total number of individual frogs found (pooled species) was highest during the night (ca. 53%) and lowest during the day (ca. 14%). Analyzing each species separately, the number of individuals recorded was consistently higher at dusk and night for most species. Our study evidences a trend for nocturnal activity for most Atlantic Rainforest frogs, with few species having primarily diurnal habits. Those results may favor future studies and conservation efforts for amphibian species.

Glacier changes since the Little Ice Age maximum in the western Qilian Shan, northwest China, and consequences of glacier runoff for water supply

2003 ◽  
Vol 49 (164) ◽  
pp. 117-124 ◽  
Author(s):  
Liu Shiyin ◽  
Sun Wenxin ◽  
Shen Yongping ◽  
Li Gang
Keyword(s):  
Little Ice Age ◽  
Image Data ◽  
Northwest China ◽  
Ice Age ◽  
Aerial Photographs ◽  
Equilibrium Line Altitude ◽  
North West ◽  
Glacier Changes ◽  
Glacier Runoff ◽  
Topographical Maps

AbstractBased on aerial photographs, topographical maps and the Landsat-5 image data, we have analyzed fluctuations of glaciers in the western Qilian Shan, north-west China, from the Little Ice Age (LIA) to 1990. The areas and volumes of glaciers in the whole considered region decreased 15% and 18%, respectively, from the LIA maximum to 1956. This trend of glacier shrinkage continued and accelerated between 1956 and 1990. These latest decreases in area and volume were about 10% in 34 years. The recent shrinkage may be due either to a combination of higher temperatures and lower precipitation during the period 1956–66, or to continuous warming in the high glacierized mountains from 1956 to 1990. As a consequence, glacier runoff from ice wastage between 1956 and 1990 has increased river runoff by 6.2 km3 in the four river basins under consideration. Besides, the equilibrium-line altitude (ELA) rise estimated from the mean terminus retreat of small glaciers <1 km long is 46 m, which corresponds to a 0.3°C increase of mean temperatures in warm seasons from the LIA to the 1950s.

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