| 1. |
- Aldenhoff, Wiebke, 1985, et al.
(författare)
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COMPARISON OF SENTINEL-1 SAR AND SENTINEL-3 ALTIMETRY DATA FOR SEA ICE TYPE DISCRIMINATION
- 2019
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Ingår i: IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium. - 9781538691540
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper near co-incidental Sentinel-1 C-band SAR imagery and Sentinel-3 SRAL Ku-band altimeter data are compared for their capabilities of sea ice type discrimination. Knowledge of sea ice type is important for climate research and safety in Arctic offshore operations. First-year ice is characterised by a low SAR backscatter intensity in both HH and HV polarisation compared to multi-year ice, while the altimeter waveform parameters show high pulse peakiness and peak power compared to multi-year ice. Thus SAR imagery and altimetry can principally discriminate different ice types. The complexity of the backscattered radar signal however impedes a clear separation of the two types for all cases. Cross comparison of the two sensors offers an opportunity of high resolution validation data, which is often lacking for sea ice studies.
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| 2. |
- Brandt, S. Anders, 1970-, et al.
(författare)
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3D geovisualization as a communication and analysis tool in fluvial geomorphology
- 2004
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Ingår i: Geoinformatics 2004. - Gävle : Gävle University Press. - 919749481X ; , s. 339-346
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Konferensbidrag (refereegranskat)abstract
- The fields of hydrology and fluvial geomorphology get more and more attention in the general public. The reason for this is changed climate patterns with increased frequencies of storms and river flooding and as a result changed geomorphology and living conditions for the inhabitants of the area. With the development of 3D geovisualization, hydrological and geomorphological processes can be better simulated and visualized. Thus not only the domain specialists, but also the general public can appreciate very complex hydrological processes and resulting geomorphology. This is of great value since a high frequency of storms and flooding has been a big issue for politicians, planners, and the general public. It is in this sense that 3D geovisualization can be an important tool for analysis and communication. Complex hydrological and geomorphological processes can be effectively simulated and analyzed by the domain specialists while efficient and effective visualization provides a common platform for communication among domain specialists and the general public. This paper will discuss and illustrate these issues using a case study of geomorphology along the Reventazón River, downstream from the Cachí Reservoir in Costa Rica, due to the release of extreme amounts of sediment during flushing of the reservoir.
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| 3. |
- Brandt, S. Anders, 1970-
(författare)
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Conceptualization of hydraulic and sedimentary processes in downstream reaches during flushing of reservoirs
- 2005
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Ingår i: Proceedings of the XXXI IAHR Congress [Elektronisk resurs]. - Seoul : Korea Water Resources Association. - 8987898237 ; , s. 2577-2588
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Konferensbidrag (refereegranskat)abstract
- The main focus of this paper is to describe the active hydraulic and sedimentary processes in downstream river reaches during flushing of sediments from reservoirs. During flushing extreme amounts of sediment may be released. Therefore, these processes are different than those downstream from dams and reservoirs not subjected to flushing. Hence, also the effects differ, which knowledge of may be of value for biologists, etc. During flushing of a reservoir a wave will be released to the downstream reaches. This wave can be divided into one water part and one sediment part. Initially they are in phase with each other, but with increased distance downstream from the dam, the transported sediment lags behind the water due to different traveling velocities. The paper treats when and where sedimentation occurs, and how this is related to the different traveling velocities of water and sediment. Also included are discussions on how the downstream effects during flushing differ from non-flushing effects, how visualization of effects can enhance both the analysis and communication with planners, politicians, etc., as well as discussions on how the studies of these effects can benefit from improved field-work methods.
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| 4. |
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| 5. |
- Hauber, Ernst, et al.
(författare)
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DEBRIS FLOW FANS AND PERMAFROST LANDFORMS ON SVALBARD (NORWAY): TERRESTRIAL ANALOGUES FOR MARTIAN MID-LATITUDE PERIGLACIAL LANDSCAPES.
- 2010
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Ingår i: 41st Lunar and Planetary Science Conference. ; :1922
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Konferensbidrag (refereegranskat)abstract
- Many young landforms on Mars that were probably formed by exogenic processes show a latitude- dependent geographic distribution. They include surface mantling, lobate debris aprons, lineated valley fill, and concentric crater fill, viscous flow features, gullies, and patterned ground. Collectively, these landforms are hypothesized to represent the surface records of Martian ice ages that were induced by astronomical forcing and associated climate changes. Previous studies often considered just one of the features in isolation (e.g., gullies), without taking into account the geomorphologic context. A more comprehensive investigation of the full assemblage of landforms (landscape analysis), however, has the potential to reduce the ambiguity in interpreting landforms (the problem of equifinality, e.g., in the case of pingos), and to reveal the evolution of the climatic environment in more detail. Here we present permafrost landforms of Svalbard (Norway) as useful terrestrial analogues for the suite of possible periglacial landforms that are typically found at mid-latitudes on Mars. We build on our previous investigations of gullies and fans, and include a number of classical periglacial landforms (patterned ground, rock glaciers, pingos) that all have close morphological analogues on Mars. Based on this comparison, we propose an evolutionary scenario which helps to understand the sequential formation of the Martian landforms into their present state.
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| 6. |
- Johnson, Mark D., 1954, et al.
(författare)
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SUBMARINE PUSH MORAINES OF THE MIDDLE SWEDISH END MORAINE ZONE
- 2011
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Ingår i: Geological Society of America abstracts with programs Minneapolis 2011.
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Konferensbidrag (refereegranskat)abstract
- During the Younger Dryas cold event (YD), the Scandinavian Ice Sheet formed the Middle Swedish end-moraine zone (MSEMZ) in south-central Sweden. The area around Skara was below sea level during the YD, and thick marine, varved clay was deposited proglacially on scoured bedrock in the ocean prior to, during, and after the YD. Recent highway exposures in four of the seven ridges in the MSEMZ reveal that, during overall retreat, the ice margin oscillated and, during each oscillation, deformed the marine clay into moraine ridges. The push moraines have little to no till, and then only on the proximal sides. A range of deformation structures are present including folded-and-thrusted to remobilized varved clay. At Ledsjö, a double oscillation is apparent with a grounding-line fan of sand formed between the two oscillations, which was then deformed. The grounding-line-fan sands are faulted and boudinized within 100 m of the former ice margin. Sand in boudins in places retains primary sedimentary structures, but elsewhere show fluidized flow. Farther up-ice, the clay and sands are complexly sheared along down-glacier-dipping reverse faults of several scales (cm to 10´s of m) indicating a subglacial tensional environment. At Ledsjö and Gullhammar, an upper, structureless clay likely represents proglacial, submarine, mudflow sediment deposited on the distal slope of the moraine. These exposures provide models for recent submarine push moraines imaged in fjords in Norway and Svalbard.
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| 7. |
- Sahlin, Eva A.U. 1971-, et al.
(författare)
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The Geomorphological Map of Wales and its use in Geoconservation Assessment (poster)
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A geomorphological map is probably the most comprehensive way of illustrating the landform distribution, surface form, material, age, and the processes responsible for the landscape look. As such geomorphological maps are invaluable in the fields of geoconservation assessment, evaluation and management. It is therefore an oddity, as well as an inconvenience, that there is no systematic landform inventory or mapping of the geomorphology that is comparable to the surveys undertaken for geology or soils in the UK. For that purpose the project of “Developing a Geomorphological Map of Wales” was initiated by the Countryside Council for Wales (CCW) as part of a PhD project investigating the Quaternary glaciations of Wales.To develop a mapping methodology suitable for the Welsh landscape, three contrasting areas were selected to provide a wide range of geomorphological features. Aerial photography, satellite imagery, digital elevation models, and field investigations of landform/sediment associations, formed the foundation for landform interpretation, which were compiled in a GIS.Geomorphological maps of Cadair Idris, and the Central and North Cambrian Mountains were produced, scale 1:10 000 – 1:25 000. The maps form an extensive inventory of the geomorphological geodiversity, and were used for providing data to palaeoglaciological reconstructions and making geoconservation recommendations to the CCW. The recommended sites are of regional interest; their rareness, distinct morphology, interesting research and educational value makes them worthy of RIGS (Regional Important Geodiversity Sites) protection.A Geomorphological Map of Wales has the potential for wider practical, scientific and educational benefits, such as for governmental bodies, local authority planners, tourism, researchers, teachers, landowners and land managers. Without a full account of all the geomorphological components of a landscape, there can be no full understanding of the landscape history or the various landforming processes. Important geodiversity sites may be overlooked, badly managed or lost before their full potential are realised.
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| 8. |
- Chrysoulakis, N, et al.
(författare)
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7E.3: Urban Energy Balance from Space: the URBANFLUXES Project
- 2018
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Ingår i: 10th International Conference on Urban Climate/14th Symposium on the Urban Environment, New York, US, August 2018.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The H2020-Space project URBANFLUXES investigated the potential of Copernicus Sentinels to retrieve the key components of the Urban Energy Budget (UEB). The Discrete Anisotropic Radiative Transfer (DART) model was used to estimate the net all-wave radiation fluxes. The storage heat flux was determined using the Element Surface Temperature Method (ESTM) after being modified to use satellite observations. Turbulent sensible and latent heat fluxes were estimated with the Aerodynamic Resistance Method (ARM). The fluxes were evaluated with in-situ flux measurements in London, Basel and Heraklion. URBANFLUXES prepared the ground for further innovative exploitation of Earth Observation data in climate variability studies scales and emerging applications (sustainable urban planning, mitigation technologies) to benefit climate change mitigation and adaptation. The wide range of data produced (e.g. land cover, vegetation phenology, surface morphology) have a much large possible applications. This project website (http://urbanfluxes.eu) provides more detailed information.
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| 9. |
- Hellqvist, Magnus, 1964-
(författare)
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A natural spring as a water resource in a landscape changing from sea to land in southcentral Sweden
- 2016
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Ingår i: Theme C – Landscapes and Water.
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Konferensbidrag (refereegranskat)abstract
- A natural spring that was revealed during archaeological excavations in Nibble (west of Enköping, Sweden) was investigated through the excavation and analysis of insect remains in order to understand landscape development in a landscape changing from seabed to terrestrial land. Sweden has been heavily affected by uplift following the terminal glaciation (Weichsel) in Scandinavia. The study area rose above sea level around 1200 BC. The spring was found in connection with the northern part of a large settlement and religious area, dating from the Younger Bronze Age and Pre-Roman Iron Age (1100-300 BC). However, 14Cdating from the lower and upper parts of the spring yielded a stratigraphic age range of 670- 870 to 660-810 AD, respectively, and we conclude that the site was probably abandoned in the late Iron Age (600-800 AD). A half-circle boulder construction at the site provides clear evidence that the natural spring was used and maintained early in prehistory, probably during the Bronze Age, and potentially cleaned at irregular periods. The insect assemblage was dominated by beetles (Coleoptera) indicative of open landscapes, grazing land and forested environments, suggesting that the spring was situated between arable land and forests, close to the former coastline. The high frequency of ground beetles (Carabidae) revealed the former ground conditions, correlating well with inorganic to organic composition. Two presently IUCN Red-Listed species that do not occur in the current fauna were found, indicating a radical change in the agricultural landscape over the last 1200 years.
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| 10. |
- Sahlin, Eva A.U. 1971-, et al.
(författare)
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Connectivity analyses of valley patterns reveal Devensian glacial drainage activity in Mid-Wales (poster)
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Connectivity analyses of valley patterns from detailed digital elevation models, and interpretation of satellite images and aerial photographs show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along Silurian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross profiles and valley spurs typical of valleys formed by fluvial processes.The connectivity analyses show that the Dyfi basin exhibits a purely dendritic pattern with little glacial modification of the preglacial fluvial valley pattern in form of valley breaching. It is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. This suggests a complex glacial drainage history, where cold-based ice was not only confined to the interior uplands, but also covered low-altitude areas previously believed to be a major drainage conduit for the Welsh Ice Cap. This indicates that Late Devensian glacial erosion was not as intense as previously believed and larger areas might have been overlain by cold-based ice.
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