An early Holocene Greenland whale from Melville Bugt, Greenland

2008 ◽  
Vol 69 (1) ◽  
pp. 72-76 ◽  
Author(s):  
Ole Bennike
Keyword(s):  
Age Determination ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Holocene ◽  
Balaena Mysticetus ◽  
Similar Position ◽  
Radiocarbon Age

Radiocarbon age determination of a Greenland whale (Balaena mysticetus) vertebra from Melville Bugt in northwestern Greenland yields an age of 9259–8989 cal yr BP. The margin of the Greenland Ice Sheet in Melville Bugt was situated behind its AD 1950–2000 position in the early Holocene, at a similar position to that being reached following rapid retreat in recent years. Such an early deglaciation of areas close to the Greenland Ice Sheet is unusual. This probably reflects the unique glaciological setting resulting from the narrow fringe of ice-free islands and peninsulas and offshore waters with deep areas that characterize this part of Greenland. The timing of Greenland Ice Sheet retreat to its present margin varies significantly around Greenland.

scholarly journals The Determination of Snow Albedo from Satellite Measurements Using Fast Atmospheric Correction Technique

2020 ◽  
Vol 12 (2) ◽  
pp. 234 ◽  
Author(s):  
Alexander Kokhanovsky ◽  
Jason E. Box ◽  
Baptiste Vandecrux ◽  
Kenneth D. Mankoff ◽  
Maxim Lamare ◽  
...  
Keyword(s):  
Atmospheric Correction ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Correction Algorithm ◽  
Satellite Measurements ◽  
Snow Albedo ◽  
Single View ◽  
French Alps ◽  
Correction Technique

We present a simplified atmospheric correction algorithm for snow/ice albedo retrievals using single view satellite measurements. The validation of the technique is performed using Ocean and Land Colour Instrument (OLCI) on board Copernicus Sentinel-3 satellite and ground spectral or broadband albedo measurements from locations on the Greenland ice sheet and in the French Alps. Through comparison with independent ground observations, the technique is shown to perform accurately in a range of conditions from a 2100 m elevation mid-latitude location in the French Alps to a network of 15 locations across a 2390 m elevation range in seven regions across the Greenland ice sheet. Retrieved broadband albedo is accurate within 5% over a wide (0.5) broadband albedo range of the (N = 4155) Greenland observations and with no apparent bias.

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.

XXV.—The Determination of Temperature Gradients over the Greenland Ice Sheet by Optical Methods

1957 ◽  
Vol 64 (4) ◽  
pp. 381-397
Author(s):  
R. A. Hamilton
Keyword(s):  
Temperature Gradient ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Temperature Gradients ◽  
Lower Atmosphere ◽  
Optical Methods ◽  
Snow Surface ◽  
Vertical Angle ◽  
Gradient Measurements

SynopsisThe temperature gradient in the lower atmosphere can be directly determined by measuring the optical refractive index of the air. This method is suitable for use on the Greenland ice sheet where errors introduced by water vapour are small, and where the strong solar radiation reflected by the snow surface makes it difficult to measure temperature differences over height differences of about I metre.The refraction was measured by observing the apparent vertical angle of each of a set of targets at distances up to 4 km. from a theodolite. The refraction was found to vary linearly with the distance of the target. The true vertical angle to the targets was determined when a second theodolite was available and reciprocal sights could be taken with it from the site of target to the fixed theodolite. The true vertical angle varied with time due to slow descent of the theodolite as the firn slumped; a correction for this was made. The standard error of the temperature gradient measurements was about 1.5 × 10−2 C.° per metre. It is considered that the method could be developed and improved so that over a range of only 100 metres temperature gradients could be measured to an accuracy of about 0·1° C. per metre.

Holocene emergence at Cape Herschel, east-central Ellesmere Island, Arctic Canada: implications for ice sheet configuration

1992 ◽  
Vol 29 (9) ◽  
pp. 1958-1980 ◽  
Author(s):  
Weston Blake Jr.
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Convincing Evidence ◽  
Ellesmere Island ◽  
East Central ◽  
Radiocarbon Age ◽  
Ice Stream ◽  
Emergence Curve ◽  
Late Wisconsinan

Twenty-five radiocarbon age determinations on marine molluscs, basal organic pond sediments, charred remains in archeological sites, and a variety of other materials have allowed the construction of an emergence curve for Cape Herschel, east-central Ellesmere Island (78°35′N, 74°40′W). Only a narrow fringe of land is present between the Prince of Wales Icefield and Smith Sound, yet emergence of the order of 135 m has taken place during the last 8500–8700 radiocarbon years. The highest in situ shells were collected at an elevation of 107.5 m, and ages of 8470 ± 100 BP (GSC-3314) and 8230 ± 70 BP (TO-230) were obtained on this material.The spectacular and fresh-appearing glacial sculpture along both sides of Smith Sound, coupled with the rapid emergence in Holocene time and the fact that the oldest dates on marine shells at the fiord heads to the west are 3000–4000 years younger than those at Cape Herschel, provides convincing evidence that an ice stream filled Smith Sound (> 500 m deep) during the Late Wisconsinan glacial maximum. The Smith Sound Ice Stream drained southward from the Greenland Ice Sheet and the Innuitian Ice Sheet, which were confluent over Kane Basin, and it overrode the top of Pim Island (550 m asl). Massive melt-off of ice must have been occurring at the transition from Pleistocene to Holocene time, and this melting continued until the mid-Holocene, when all investigated outlet glaciers were behind their present positions.

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

2012 ◽  
Vol 8 (5) ◽  
pp. 5263-5291 ◽  
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 reveal 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 a 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 a 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 early Holocene GIS is crucial for understanding the HTM characteristics in the Nordic Seas area. This implies that the 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 The Determination of Snow Albedo from Satellite Measurements Using Fast Atmospheric Correction Technique

2019 ◽  
Author(s):  
Alexander Kokhanovsky ◽  
Jason E. Box ◽  
Baptiste Vandecrux ◽  
Kenneth Mankoff ◽  
Maxim Lamare ◽  
...  
Keyword(s):  
Atmospheric Correction ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Correction Algorithm ◽  
Satellite Measurements ◽  
Snow Albedo ◽  
Single View ◽  
French Alps ◽  
Correction Technique

We present a simplified atmospheric correction algorithm for the snow/ice albedo retrieval using single view satellite measurements. The validation of the technique is performed using Ocean and Land Colour Instrument (OLCI) on board Copernicus Sentinel - 3 satellite and ground spectral or broadband albedo measurements from locations on the Greenland ice sheet and in the French Alps. Through comparison with independent ground observations, the technique is shown to perform accurately in a range of conditions from a 2100 m elevation mid-latitude location in the French Alps to a network of 15 locations across a 2390 m elevation range in seven regions across the Greenland ice sheet. Retrieved broadband albedo is accurate within 5% over a wide (0.5) broadband albedo range of the (N = 4,155) Greenland observations and with no apparent bias.

scholarly journals Maximum Southwest Greenland Ice Sheet Recession in the Early Holocene

2020 ◽  
Vol 47 (1) ◽  
Author(s):  
A. J. Lesnek ◽  
J. P. Briner ◽  
N. E. Young ◽  
J. K. Cuzzone
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Holocene ◽  
Southwest Greenland

scholarly journals Ages of Charcoal Samples of Geomorphologic Interest in Northeast Hungary

Radiocarbon ◽  
1980 ◽  
Vol 22 (3) ◽  
pp. 774-777 ◽  
Author(s):  
Eva Csongor ◽  
Zoltán Borsy ◽  
Ilona Szabô
Keyword(s):  
Sand Dune ◽  
Soil Layer ◽  
Age Determination ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Radiocarbon Age ◽  
Fossil Soil ◽  
Hungarian Plain ◽  
The Last Glacial

There are extended wind-blown sand territories in the northeastern part of the Great Hungarian Plain. Wind-blown sand migration periods were distineuished by means of radiocarbon age determination of charcoal samples found in the same type of a thin soil layer of chernozem character in different sand dune exposures. The ages of the samples were determined by proportional counter, and are around 12 000 years BP. This thin fossil soil layer, which is regionally spread in the northeast Hungarian wind-blown sand areas, presents a chronological mark between the blown sand forms evolved in the last glacial period and in the Holocene.

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