scholarly journals Early Holocene temperature variability in the Nordic Seas: The role of oceanic heat advection versus changes in orbital forcing

2011 ◽  
Vol 26 (4) ◽  
Author(s):  
Bjørg Risebrobakken ◽  
Trond Dokken ◽  
Lars Henrik Smedsrud ◽  
Carin Andersson ◽  
Eystein Jansen ◽  
...  
Keyword(s):  
Temperature Variability ◽  
Early Holocene ◽  
Orbital Forcing ◽  
Heat Advection ◽  
Nordic Seas

The Role of Oceanic Heat Advection in the Evolution of Tropical North and South Atlantic SST Anomalies*

2006 ◽  
Vol 19 (23) ◽  
pp. 6122-6138 ◽  
Author(s):  
Gregory R. Foltz ◽  
Michael J. McPhaden
Keyword(s):  
Surface Flux ◽  
South Atlantic ◽  
Shortwave Radiation ◽  
Heat Advection ◽  
Horizontal Advection ◽  
Latent Heat Loss ◽  
North And South ◽  
Sst Gradient ◽  
Sst Anomalies

Abstract The role of horizontal oceanic heat advection in the generation of tropical North and South Atlantic sea surface temperature (SST) anomalies is investigated through an analysis of the oceanic mixed layer heat balance. It is found that SST anomalies poleward of 10° are driven primarily by a combination of wind-induced latent heat loss and shortwave radiation. Away from the eastern boundary, horizontal advection damps surface flux–forced SST anomalies due to a combination of mean meridional Ekman currents acting on anomalous meridional SST gradients, and anomalous meridional currents acting on the mean meridional SST gradient. Horizontal advection is likely to have the most significant effect on the interhemispheric SST gradient mode through its impact in the 10°–20° latitude bands of each hemisphere, where the variability in advection is strongest and its negative correlation with the surface heat flux is highest. In addition to the damping effect of horizontal advection in these latitude bands, evidence for coupled wind–SST feedbacks is found, with anomalous equatorward (poleward) SST gradients contributing to enhanced (reduced) westward surface winds and an equatorward propagation of SST anomalies.

The Peopling of the Baraba Forest-Steppe in the Neolithic: Cranial Evidence

2021 ◽  
Vol 49 (1) ◽  
pp. 133-146
Author(s):  
T. A. Chikisheva ◽  
D. V. Pozdnyakov
Keyword(s):  
Local Population ◽  
Principal Component ◽  
Early Holocene ◽  
Russian Plain ◽  
Northern Eurasia ◽  
Forest Steppe ◽  
Early Neolithic ◽  
Population Continuity ◽  
Lake Systems

On the basis of statistical analysis of craniometric data relating to Mesolithic and Neolithic samples from northern Eurasia, we discuss the peopling of the Baraba forest-steppe in the Early Holocene. This region is represented by samples from Sopka-2/1 (early sixth millennium BC), Protoka (late fifth to early fourth millennia BC), Korchugan (early-mid sixth millennium BC), and Vengerovo-2A (late sixth millennium BC). The results of the principal component analysis are interpreted in the context of debates over the role of autochthonous traditions in the Neolithic. During the Preboreal period (10 ka BP), large parts of the Baraba forest-steppe were flooded by the transgression of lake systems during climatic warming. This may have caused depopulation, lasting for at least a millennium. The Early Holocene people of Baraba were an offshoot of Meso-Neolithic populations of the northwestern Russian Plain. On that basis, the Early Neolithic populations of Baraba were formed. Direct population continuity is traceable only through the Chalcolithic. Since the late sixth millennium BC, however, the local population had incorporated migrants from the Pit-Comb Ware area in the central Russian Plain and, indirectly (via the Neolithic Altai), from the Cis-Baikal area.

scholarly journals The Holocene thermal maximum in the Nordic Seas: the impact of Greenland Ice Sheet melt and other forcings in a coupled atmosphere–sea-ice–ocean model

2013 ◽  
Vol 9 (4) ◽  
pp. 1629-1643 ◽  
Author(s):  
M. Blaschek ◽  
H. Renssen
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Holocene ◽  
Surface Cooling ◽  
Holocene Climate ◽  
Nordic Seas ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Thermal Maximum ◽  
The Impact

Abstract. The relatively warm early Holocene climate in the Nordic Seas, known as the Holocene thermal maximum (HTM), is often associated with an orbitally forced summer insolation maximum at 10 ka BP. The spatial and temporal response recorded in proxy data in the North Atlantic and the Nordic Seas reveals a complex interaction of mechanisms active in the HTM. Previous studies have investigated the impact of the Laurentide Ice Sheet (LIS), as a remnant from the previous glacial period, altering climate conditions with a continuous supply of melt water to the Labrador Sea and adjacent seas and with a downwind cooling effect from the remnant LIS. In our present work we extend this approach by investigating the impact of the Greenland Ice Sheet (GIS) on the early Holocene climate and the HTM. Reconstructions suggest melt rates of 13 mSv for 9 ka BP, which result in our model in an ocean surface cooling of up to 2 K near Greenland. Reconstructed summer SST gradients agree best with our simulation including GIS melt, confirming that the impact of the early Holocene GIS is crucial for understanding the HTM characteristics in the Nordic Seas area. This implies that modern and near-future GIS melt can be expected to play an active role in the climate system in the centuries to come.

scholarly journals Orbital forcing and role of the latitudinal insolation/temperature gradient

2008 ◽  
Vol 32 (2-3) ◽  
pp. 143-165 ◽  
Author(s):  
Basil A. S. Davis ◽  
Simon Brewer
Keyword(s):  
Temperature Gradient ◽  
Orbital Forcing

Influence of Nordic Seas dynamics on the Atlantic Water propagation and its impacts on sea ice concentration.

2021 ◽  
Author(s):  
Sourav Chatterjee ◽  
Roshin P Raj ◽  
Laurent Bertino ◽  
Nuncio Murukesh
Keyword(s):  
Sea Ice ◽  
Deep Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Deep Water Formation ◽  
Sea Ice Concentration ◽  
Nordic Seas ◽  
Ice Concentration ◽  
Water Formation

<p>Enhanced intrusion of warm and saline Atlantic Water (AW) to the Arctic Ocean (AO) in recent years has drawn wide interest of the scientific community owing to its potential role in ‘Arctic Amplification’. Not only the AW has warmed over the last few decades , but its transfer efficiency have also undergone significant modifications due to changes in atmosphere and ocean dynamics at regional to large scales. The Nordic Seas (NS), in this regard, play a vital role as the major exchange of polar and sub-polar waters takes place in this region. Further, the AW and its significant modification on its way to AO via the Nordic Seas has large scale implications on e.g., deep water formation, air-sea heat fluxes. Previous studies have suggested that a change in the sub-polar gyre dynamics in the North Atlantic controls the AW anomalies that enter the NS and eventually end up in the AO. However, the role of NS dynamics in resulting in the modifications of these AW anomalies are not well studied. Here in this study, we show that the Nordic Seas are not only a passive conduit of AW anomalies but the ocean circulations in the Nordic Seas, particularly the Greenland Sea Gyre (GSG) circulation can significantly change the AW characteristics between the entry and exit point of AW in the NS. Further, it is shown that the change in GSG circulation can modify the AW heat distribution in the Nordic Seas and can potentially influence the sea ice concentration therein. Projected enhanced atmospheric forcing in the NS in a warming Arctic scenario and the warming trend of the AW can amplify the role of NS circulation in AW propagation and its impact on sea ice, freshwater budget and deep water formation.</p>

scholarly journals The Role of Basketry in Early Holocene Small Seed Exploitation: Implications of a Ca. 9,000 Year-Old Basket from Cowboy Cave, Utah

2008 ◽  
Vol 73 (1) ◽  
pp. 83-102 ◽  
Author(s):  
Phil R. Geib ◽  
Edward A. Jolie
Keyword(s):  
North America ◽  
Great Basin ◽  
Processing Technique ◽  
Early Holocene ◽  
Western North America ◽  
Seed Processing ◽  
Small Seed ◽  
Food Exploitation ◽  
The Continuum

Despite ranking at the low end of the continuum in net caloric benefit relative to other foods, small seeds assumed great dietary importance in many parts of the world, including western North America. In a series of publications, Adovasio (1970a, 1974, 1980, 1986) argued that coiled basketry technology was invented in the eastern Great Basin during the early Holocene as a specialized food-processing technique. Coiled baskets are indeed useful for collecting and processing seeds, but it does not necessarily follow that they were originally designed for this purpose. A whole basket recently discovered at Cowboy Cave in southeastern Utah returned an AMS radiocarbon assay of 7960 ± 50 B.P., making it currently the earliest directly dated coiled basket from the Americas. This basket is not a parching tray and likely had nothing to do with harvesting seeds. We discuss the implications of this find with regard to tracking the temporal spread of coiled basketry technology in western North America and the role of coiled and twined forms in the initiation of small seed exploitation. Coiled and twined baskets for small seed processing may result from reconfiguration of existing technologies to create novel forms suited to a new food exploitation strategy.

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