The occurrence of several high-magnitude abrupt climatic changes during the last glacial period (~120-10 ka BP) was first recognised within the Greenland deep ice-core records. Subsequent identification of similar climatic variations has demonstrated the potential global significance of these events. Three of these millennial-scale events occurred during Marine Isotope Stage (MIS) 4 (~79-59 ka BP), a period characterised by cooler global temperatures. An understanding of the forcing mechanisms and the environmental responses to these events is currently unattainable due to chronological uncertainties and the inability to precisely synchronise disparate records. Tephrochronology, however, has the potential to facilitate high-precision ice-marine correlations by tracing isochronous horizons between different sequences spanning this period. This potential is demonstrated through the construction of the first tephrochronological framework for MIS 4 within the North Atlantic region. Fourteen cryptotephra horizons are identified within the NGRIP and GRIP ice-cores and the MD04-2822 marine core. Both major and trace element compositions are presented for these previously unknown tephra horizons and form the backbone of this framework. In addition, high-precision, independent age estimates have been assigned to the horizons identified within the ice-core sequences. This framework represents a significant first step towards the regional and potentially hemispheric synchronisation of MIS 4 climatic archives. As well as providing the first evidence for the activity of Icelandic volcanic systems during MIS 4, this framework also demonstrates the widespread dispersal of basaltic-trachybasaltic products from the Jan Mayen volcanic region and potentially the deposition of Japanese volcanic material over Greenland. In addition, investigations of laser ablation inductively coupled plasma mass spectrometry have demonstrated that reliable trace element characterisations can be obtained from tephra shards?20 ?m in diameter, which opens up new possibilities for the incorporation of this technique in distal tephra studies.

The climate variability over the North Atlantic region is described in the 10-50 year band, using a 500-year integration of the Hamburg ECHAMl/LSG coupled general circulation model. In order to isolate nearly periodic components of the atmosphere and the ocean, the multichannel version of the singular spectrum analysis (MSSA) is applied to 11 components of the climate system. In doing so the main focus is on the turbulent exchange between the two subsystems. One interdecadal oscillation of the system ocean and atmosphere is detected with a period of about 18 years. The associated anomalies of sea level pressure (SLP) are situated east of Newfoundland while these of the geopotential height at 500 hPa are slightly shifted to the East. Both the fields undergo a primarily standing oscillation. The sea surface temperature (SST) and the sub surface temperature anomalies have a large extension along the 40° N latitude circle with most of their variability south of Newfoundland. lt is found that the SST anomaly is primarily generated by the temperature advection in the upper ocean layer which is coupled to the Subpolar Gyre strength and Ekman pumping vertical velocity. Both the processes are forced by the atmosphere. In a further analysis applied only to the SST and the Geopotential height at 500 hPa over the whole Northern Hemisphere this 18 year mode was also isolated. The modes obtained by the local and hemispheric analyses are well correlated both in time and space, suggesting a more active role of atmosphere than of the ocean, in addition a strong modulation of the amplitude of the oscillation due to local processes over the North Atlantic was detected. / Die Klimavariabilität über dem Nordatlantik wird anhand einer 500 Jahre Integration des Hamburger gekoppelten Klimamodels ECHAMl/LSG untersucht. Um periodische Komponenten in Ozean und Atmosphäre zu isolieren, wird die MSSA ("multichannel singular spectrum analysis") auf 11 Komponenten des Klimasystems angewandt. Bei den Analysen wird besonderes Augenmerk auf den turbulenten Austausch zwischen beiden Subsystemen gelegt. Es kann eine Oszillation des gekoppelten Systems mit einer Periode von etwa 18 Jahren detektiert werden. Die Anomalie des Bodendrucks weist ihre maximale Amplitude östlich von Neufundland auf, während die Anomalie des 500 hPa Geopotentials leicht östlich dazu verschoben ist. Die Anomalie der SST zeigt ihre größte Variabilität südlich von Neufundland. Diese wird im wesentlichen durch die Temperaturadvektion in der oberen Ozeanschicht generiert, welche im wesentlichen an den subpolaren ozeanischen Wirbel sowie an das "Ekman pumping" gekoppelt ist. Beide Prozesse werden durch die Atmosphäre angetrieben. In einer weiteren Analyse, in der die MSSA auf die SST und das 500 hPa Geopotential der gesamten nördlichen Hemisphäre angewandt wird, kann ebenfalls ein Oszillation von 18 Jahren detektiert werden. Diese Mode korreliert räumlich und zeitlich gut mit dem der lokalen Analyse über dem Nordatlantik, welches auf ein aktivere Rolle der Atmosphäre hinweist. Die starken Unterschiede der Amplitudenmodulation könnten durch lokale Prozesse bedingt sein.

The climate variability over the North Atlantic region is described in the 10-50 year band, using a 500-year integration of the Hamburg ECHAMl/LSG coupled general circulation model. In order to isolate nearly periodic components of the atmosphere and the ocean, the multichannel version of the singular spectrum analysis (MSSA) is applied to 11 components of the climate system. In doing so the main focus is on the turbulent exchange between the two subsystems. One interdecadal oscillation of the system ocean and atmosphere is detected with a period of about 18 years. The associated anomalies of sea level pressure (SLP) are situated east of Newfoundland while these of the geopotential height at 500 hPa are slightly shifted to the East. Both the fields undergo a primarily standing oscillation. The sea surface temperature (SST) and the sub surface temperature anomalies have a large extension along the 40° N latitude circle with most of their variability south of Newfoundland. lt is found that the SST anomaly is primarily generated by the temperature advection in the upper ocean layer which is coupled to the Subpolar Gyre strength and Ekman pumping vertical velocity. Both the processes are forced by the atmosphere. In a further analysis applied only to the SST and the Geopotential height at 500 hPa over the whole Northern Hemisphere this 18 year mode was also isolated. The modes obtained by the local and hemispheric analyses are well correlated both in time and space, suggesting a more active role of atmosphere than of the ocean, in addition a strong modulation of the amplitude of the oscillation due to local processes over the North Atlantic was detected. / Die Klimavariabilität über dem Nordatlantik wird anhand einer 500 Jahre Integration des Hamburger gekoppelten Klimamodels ECHAMl/LSG untersucht. Um periodische Komponenten in Ozean und Atmosphäre zu isolieren, wird die MSSA ('multichannel singular spectrum analysis') auf 11 Komponenten des Klimasystems angewandt. Bei den Analysen wird besonderes Augenmerk auf den turbulenten Austausch zwischen beiden Subsystemen gelegt. Es kann eine Oszillation des gekoppelten Systems mit einer Periode von etwa 18 Jahren detektiert werden. Die Anomalie des Bodendrucks weist ihre maximale Amplitude östlich von Neufundland auf, während die Anomalie des 500 hPa Geopotentials leicht östlich dazu verschoben ist. Die Anomalie der SST zeigt ihre größte Variabilität südlich von Neufundland. Diese wird im wesentlichen durch die Temperaturadvektion in der oberen Ozeanschicht generiert, welche im wesentlichen an den subpolaren ozeanischen Wirbel sowie an das 'Ekman pumping' gekoppelt ist. Beide Prozesse werden durch die Atmosphäre angetrieben. In einer weiteren Analyse, in der die MSSA auf die SST und das 500 hPa Geopotential der gesamten nördlichen Hemisphäre angewandt wird, kann ebenfalls ein Oszillation von 18 Jahren detektiert werden. Diese Mode korreliert räumlich und zeitlich gut mit dem der lokalen Analyse über dem Nordatlantik, welches auf ein aktivere Rolle der Atmosphäre hinweist. Die starken Unterschiede der Amplitudenmodulation könnten durch lokale Prozesse bedingt sein.

No description available.

Following the German occupation of Denmark on April 9th 1940 Danish representatives were left to their own devices and their positions in their respective host-countries became very much dependent upon the goodwill shown to them by their host-governments and, in the case of the Faroe Islands, Iceland and Greenland, the governments and officials of the occupying forces. With their connections with the Government in Copenhagen severed the main task of the Danish representatives was to secure Danish interests in the North Atlantic Territories as well as elsewhere. The fact that Denmark had not put up a fight to defend her neutrality and the subsequent collaboration of the Danish Government with the German occupiers counted against the Danish representatives abroad. However, the Danes were able to exercise a remarkable level of influence on the British and Americans with regard to their policies towards the North Atlantic Area. The extent of influence was mainly due to the entrepreneurship of each individual, the constitutional status of the territory as part of the Kingdom of Denmark, and also due to strategic importance attached by the occupying forces' governments to the occupied territories in question. This latter point became especially apparent in the power struggle amongst the Danish representatives that emerged from the lack of a Danish Government in exile. It became important to the British and the Americans that it was the Danish representative in their country, who emerged as the victor of this power struggle, because that would help to secure their future interests in the North Atlantic territories. The Danish representatives were thus in some cases shown more goodwill and attention than their Norwegian colleagues, although the Norwegians had put up a brave fight against the Germans and had joined the allied side. The North Atlantic area proved very important to the general war policy of the British and Americans during Second World War. British policies were much dependent upon the Americans and Greenland and Iceland became instrumental in the increased involvement of the Americans in the war.

The subject of this study is Viking-Late Norse settlement (c. AD800-1200) in the North Atlantic, focusing on Orkney and on longhouse complexes constructed on mounds. For the first time these mound settlements are investigated as a group and as deliberately constructed mounds. Settlement mounds in Orkney are also closely associated with nearly 40 Skaill ON skáli ('hall') place-names, which place-names linked the sites with the social and economic networks of Orkney's peripatetic leaders. This association is examined more closely. The analysis also demonstrates that constructing settlements on mounds required particular building techniques, which relied heavily on the use of midden-type material. Those techniques are examined using new and freshly analysed material from published and grey literature-published excavations and surveys of sites from the Viking-Late Norse period in Orkney and elsewhere. Three core data-sets were established to provide the evidential basis: the first, also drawing on site-visits, looking broadly at mound landscapes and skáli-areas in Orkney; the second at the building techniques and materials used on settlement mounds; and the third, also requiring site-visits, at all the skáli place-name sites. The possible origins of settlement mound living in the settlers' Scandinavian homelands are investigated, then the extent to which mound living was also followed in Shetland, Caithness and the Western Isles, and finally in previously unoccupied lands, using Iceland as a case study. The mound-sites, their archaeology, mound architecture, place-names and landscape setting are also analysed in a new theoretical framework to reach fresh understandings of Viking-Late Norse settlement in Orkney. The analysis thus considers the wider cultural significance of constructing and living on settlement mounds, and what that communicated about Viking-Late Norse society. The thesis argues that Viking-Late Norse groups chose prominently-placed sites for their visual dominance and commanding views, but also that the rebuilding of mound structures in one spot, and building out and up of the mound itself using midden material, set strong cultural messages about stability, continuity and association with the surrounding landscape. The mounds were complex features of culturally meaningful architecture.

Four continuous high-resolution peat records for the Holocene have been reconstructed across a ~300km transect from Shebster in Caithness to Yell in the Shetland Isles. These records describe the nature and extent of North Atlantic climate changes inferred from indicators of storminess and minerogenic aeolian dust, and are supported by radiogenic isotope analysis, tephrochronology and radiocarbon dating. The environmental changes at all four sites displays a significant degree of synchrony in response to changes in the position of the polar front jet (PFJ) stream and the phase of the North Atlantic Oscillation (NAO). Bromine concentrations in the peat, derived from sea spray, are used to reconstruct storm frequency and storm intensity, and mire surface wetness is used as an indicator of longer-term climate shifts. The results suggest a strong link between positive phases of the NAO and storminess. Subtle differences between the bromine concentrations and the mire surface wetness suggest that high intensity but perhaps less frequent periods of storminess are not necessarily associated with a wetter climate. Atmospheric minerogenic dust concentrations are used to reconstruct large-scale climate changes across the wider North Atlantic region. The results suggest a sympathy between dust activity and periods of glacial advance and a negative index of the NAO. Radiogenic isotope analysis suggests that the smallest particles may originate from Iceland.

Over the past two decades, environmental history as an approach to the understanding and explanation of historical processes has become gradually fashionable amongst academics; empirical data collected over the North Atlantic proposed new trends with regards to economic patterns during the Viking Age. The increasing number of Viking Age sites exposed in Iceland, the amount of zooarchaeological collections highlighting an abundant presence of fish bones in the overall archaeofauna, together with one’s expertise in environmental history as well as a strong interest in socio-economic development during the Viking Age and medieval periods were many factors which help identify strengths and weaknesses with regards to the understanding of the emergence of commercial fish trade in Iceland, and to a lesser extent, the Faeroe Islands. The thesis proposes a new theory with regards to human adaptation to new environments, and subsequent economic developments based on the commercial exploitation of fish. The interdisciplinary aspect of this project using cultural sediment analysis and zooarchaeology, as well as concepts from anthropology and economic anthropology, allows for the theory to be tested by empirical data.