IAG Newsletter     

Ole Baltazar Andersen 《Journal of Geodesy》2003,76(9-10):586-596

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Climate Change Impact on Snow Coverage, Evaporation and River Discharge in the Sub-Arctic Tana Basin, Northern Fennoscandia     

Rutger Dankers  Ole Bøssing Christensen 《Climatic change》2005,69(2-3):367-392

Arctic environments are generally believed to be highly sensitive to human-induced climatic change. In this paper, we explore the impacts on the hydrological system of the sub-arctic Tana Basin in Northernmost Finland and Norway. In contrast with previous studies, attention is not only given to river discharge, but also to the spatial patterns in snow coverage and evapotranspiration. We used a distributed water balance model that was coupled to a regional climate model in order to calculate a scenario of climate change by the end of this century. Three different model experiments were performed, adopting different approaches to using the climate model output in the hydrological model runs. The results were largely consistent, indicating a much shorter snow season and, accordingly, decreased sublimation, an increase in evapotranspiration, and a shift in the annual runoff peak. As the snow-free season is extended, the amount of solar radiation that is received during this period increases significantly. The results also show important local differences in the hydrological response to climate change. For example, in the scenario runs, the snow season was more than 30 days shorter at higher elevations, but in some of the river valleys, this was up to 70 days.  相似文献   

Fast transformation of iron oxyhydroxides by the catalytic action of aqueous Fe(II)     

Hanne D. Pedersen  Dieke Postma  Ole Larsen 《Geochimica et cosmochimica acta》2005,69(16):3967-3977

Iron oxides may undergo structural transformations when entering an anoxic environment. These transformations were investigated using the isotopic exchange between aqueous Fe(II) and iron oxides in experiments with ⁵⁵Fe-labelled iron oxides. ⁵⁵Fe was incorporated congruently into a ferrihydrite, two lepidocrocites (#1 and #2), synthesised at 10°C and 25°C, respectively, a goethite and a hematite. The iron oxides were then submerged in Fe²⁺ solutions (0-1.0 mM) with a pH of 6.5. In the presence of aqueous Fe²⁺, an immediate and very rapid release of ⁵⁵Fe was observed from ferrihydrite, the two lepidocrocites and goethite, whereas in the absence of Fe²⁺ no release was observed. ⁵⁵Fe was not released from hematite, even at the higher Fe²⁺ concentration. The release rate is mainly controlled by characteristics of the iron oxides, whereas the concentration of Fe²⁺ only has minor influence. Ferrihydrite and 5-nm-sized lepidocrocite crystals attained complete isotopic equilibration with aqueous Fe(II) within days. Within this timeframe ferrihydrite transformed completely into new and more stable phases such as lepidocrocite and goethite. Lepidocrocite #2 and goethite, having larger particles, did not reach isotopic equilibrium within the timeframe of the experiment; however, the continuous slow release of ⁵⁵Fe suggests that isotopic equilibrium will ultimately be attained.Our results imply a recrystallization of solid Fe(III) phases induced by the catalytic action of aqueous Fe(II). Accordingly, iron oxides should properly be considered as dynamic phases that change composition when exposed to variable redox conditions. These results necessitate a reevaluation of current models for the release of trace metals under reducing conditions, the sequestration of heavy metals by iron oxides, and the significance of stable iron isotope signatures.  相似文献   

4416565 Method and column for collection and separation of oil,gas and water from blowing wells at the sea bed     

Ole C Ostlund 《Marine pollution bulletin》1984,15(3):120-121

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Future extreme events in European climate: an exploration of regional climate model projections   总被引：7，自引：0，他引：7  

Martin Beniston  David B. Stephenson  Ole B. Christensen  Christopher A. T. Ferro  Christoph Frei  Stéphane Goyette  Kirsten Halsnaes  Tom Holt  Kirsti Jylhä  Brigitte Koffi  Jean Palutikof  Regina Schöll  Tido Semmler  Katja Woth 《Climatic change》2007,81(1):71-83

This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape. The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures of temperature but that ground station data may still be preferred for measuring precipitation in rural settings.  相似文献   

All about water and land? Resource-related conflicts in East and West Africa revisited     

Hanne Seter  Ole Magnus Theisen  Janpeter Schilling 《GeoJournal》2018,83(1):169-187

Recent years have seen an upsurge in the numbers of studies investigating the potential link between climate variability and conflict—and particularly so quantitative studies of this relationship—without reaching any consensus on causal pathways or main findings. This study sets out to explore what the main causes of conflict between resource-user groups in arid and semi-arid areas in Sub-Saharan Africa are, with a particular focus on renewable-resource scarcity. We conduct a comparative analysis of eleven high-quality case studies of the escalation into violence of disputes between pastoralists and farmers or pastoralists in the Western Sahel and East Africa. This enables us to identify the mechanisms underpinning the actors’ motivations. Our analysis shows that the nature of these conflicts is complex. They cannot be reduced to a stimulus (resource scarcity)–response (violence) relationship. We find that drought is a contributing factor in four of the conflicts, and that a poor rainy season plays a role in a fifth one. However, resource scarcity is never the most important cause and it does not explain well the differences in conflict intensity. The most important contributor to explaining different levels of intensity is when local autochthonous and exclusionary claims are coupled with national-level political processes.  相似文献   

Range and AGC normalization in airborne discrete-return LiDAR intensity data for forest canopies   总被引：1，自引：0，他引：1  

Ilkka Korpela  Hans Ole Ørka  Juha Hyyppä  Ville Heikkinen  Timo Tokola 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(4):369-379

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A new integalacial sequence from Washington Land, Northern Greenland     

Ole Bennike  Hans. f. Jepsen 《Polar research》2000,19(2):267-270

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IAG Newsletter     

Ole Baltazar Andersen 《Journal of Geodesy》2000,74(7-8):603-620

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Cenozoic sediment distribution and tectonic movements in the Faroe region     

Morten Sparre Andersen  Tove Nielsen  Aage Bach Srensen  Lars Ole Boldreel  Anton Kuijpers 《Global and Planetary Change》2000,24(3-4)

A complex history of Cenozoic vertical movements in the Faroe region has been revealed from interpretation of geophysical and geological data, mainly offshore reflection seismic data, side-scan images, shallow cores, and onshore mapping. The history comprises several phases of tectonic disturbances observed at different scales. On the eastern margin of the Faroe Platform a late Eocene–early Oligocene phase of doming of the Faroe Platform has caused a postdepositional tilting of Eocene strata along the southern margin of the platform; a mid-Miocene phase of compressional tectonics is evidenced on seismic transects as gentle anticlines and associated reverse faults; and possible Pliocene uplift of the Faroe Islands is indicated by a progradational wedge of sediments deposited on the eastern Faroe Platform. At the continental margin/slope north of the Faroe Platform, reflection seismic data imaging the postbasalt sedimentary strata indicate three distinct tectonic events phases in the Eocene–Oligocene, Miocene and Pliocene, respectively. In contrast to the Faroe Platform the Faroe–Shetland Channel was characterised by more or less continuous subsidence dominated throughout the Cenozoic. During the Eocene, sediments deposited in the Faroe–Shetland Channel was mostly derived from a source area on the British shelf.  相似文献