Aeromagnetic survey data, Baffin Bay, North Atlantic and arctic oceans and Hudson bay

1977 ◽  
Author(s):  
M E Bower
Keyword(s):  
Survey Data ◽  
North Atlantic ◽  
Hudson Bay ◽  
Aeromagnetic Survey ◽  
Baffin Bay

scholarly journals Origins and Levels of Seasonal Forecast Skill for Sea Ice in Hudson Bay Using Canonical Correlation Analysis

2011 ◽  
Vol 24 (5) ◽  
pp. 1378-1395 ◽  
Author(s):  
Adrienne Tivy ◽  
Stephen E. L. Howell ◽  
Bea Alt ◽  
John J. Yackel ◽  
Thomas Carrieres
Keyword(s):  
Correlation Analysis ◽  
Sea Ice ◽  
Canonical Correlation Analysis ◽  
North Atlantic ◽  
Canonical Correlation ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Sea Surface ◽  
Hudson Bay ◽  
Ice Concentration

Abstract Canonical correlation analysis (CCA) is used to estimate the levels and sources of seasonal forecast skill for July ice concentration in Hudson Bay over the 1971–2005 period. July is an important transition month in the seasonal cycle of sea ice in Hudson Bay because it is the month when the sea ice clears enough to allow the first passage of ships to the Port of Churchill. Sea surface temperature (quasi global, North Atlantic, and North Pacific), Northern Hemisphere 500-mb geopotential height (z500), sea level pressure (SLP), and regional surface air temperature (SAT) are tested as predictors at 3-, 6-, and 9-month lead times. The model with the highest skill has three predictors—fall North Atlantic SST, fall z500, and fall SAT—and significant tercile forecast skill covering 61% of the Hudson Bay region. The highest skill for a single-predictor model is from fall North Atlantic SST (6-month lead). Fall SST explains 69% of the variance in July ice concentration in Hudson Bay and a possible atmospheric link that accounts for the lagged relationship is presented. CCA diagnostics suggest that changes in the subpolar North Atlantic gyre and the Atlantic multidecadal oscillation (AMO), reflected in sea surface temperature, precedes a deepening/weakening of the winter upper-air ridge northwest of Hudson Bay. Changes in the height of the ridge are reflected in the strength of the winter northwesterly winds over Hudson Bay that have a direct impact on the winter ice thickness distribution; anomalies in winter ice severity are later reflected in the pattern and timing of spring breakup. July ice concentration in Hudson Bay has declined by approximately 20% per decade between 1979 and 2007, and the hypothesized link to the AMO may help explain this significant loss of ice.

scholarly journals Evidence from 40Ar/39Ar Ages for a Churchill province source of ice-rafted amphiboles in Heinrich layer 2

1996 ◽  
Vol 42 (142) ◽  
pp. 440-446 ◽  
Author(s):  
Roberto H. Gwiazda ◽  
Sidney R. Hemming ◽  
Wallace S. Broecker ◽  
Tullis Onsttot ◽  
Chris Mueller
Keyword(s):  
North Atlantic ◽  
Drainage Basin ◽  
Ice Sheets ◽  
Bimodal Distribution ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Glacial Sediment ◽  
The North ◽  
Layer 2 ◽  
Eastern North Atlantic

Abstract40Ar/39Ar ages of most single ice-ratted amphiboles from Heinrich layer 2 (H2) from a core in the Labrador Sea, a core in the eastern North Atlantic and a core in the western North Atlantic range from 1600 to 2000 Ma. This range is identical to that for K/Ar ages from the Churchill province of the Canadian Shield that outcrops at Hudson Strait and forms the basement of the northern part of Hudson Bay. The ambient glacial sediment includes some younger and older grains derived from Paleozoic, Mesoproterozoic and Archean sources, but still the majority of the amphiboles have ages in the 1600–2000 Ma interval. The Ca/K ratios of these 1600–2000 Ma old amphiboles, however, have a bimodal distribution in contrast with the uniformity of the Ca/K ratios of H2 amphiboles. This indicates that 1600–2000 Ma old amphiboles of the ambient sediment were derived from an additional Early Proterozoic source besides Churchill province. In H2, Churchill-derived grains constitute 20–40% of the ice-rafted debris (IRD). The fraction in the ambient glacial sediment is 65–80%. Results presented here are consistent with the hypothesis that Heinrich events were produced by a sudden intensification of the iceberg discharge through Hudson Strait that mixed, in the North Atlantic, with icebergs that continued to calve from other ice sheets. The shift from mixed sources in the background sediment to a large dominance of Churchill province grains in H2 indicates that, even if calving of other ice sheets intensified during the Heinrich episode, the increase in the iceberg discharge via Hudson Strait from the Hudson Bay drainage basin of the Laurentide ice sheet was by far the largest.

scholarly journals Sensitivity of a Two-Layer Model Atmosphere to Changes in Ice-Sheet Topography

1997 ◽  
Vol 25 ◽  
pp. 246-249 ◽  
Author(s):  
Charles S. Jackson
Keyword(s):  
North Atlantic ◽  
Ice Sheet ◽  
Model Atmosphere ◽  
Hudson Bay ◽  
Surprising Result ◽  
Layer Model ◽  
The North ◽  
Two Layer Model ◽  
The North Atlantic ◽  
Ice Sheet Topography

Results are presented testing the sensitivity of a two-layer model to changes in the Laurentide ice sheet’s geometry following the collapse of the Hudson Bay ice dome. Since the ice sheet is thought to induce cooling over the North Atlantic through its mechanical effect on atmospheric circulation, the model shows a surprising result in that the removal of the Hudson Bay ice dome led to a further cooling of 4°C over the North Atlantic. This finding suggests that fluctuations in ice-sheet topography could have contributed to the climate variability witnessed in the geologic record. Further study is needed to understand the mechanism behind these results.

Isotopic evidence for changes in the origin and cycling of nitrogen in the Labrador Sea during the last 8,000 years

2020 ◽  
Author(s):  
Markus Kienast ◽  
Sam Davin ◽  
Kristin Doering ◽  
Dierk Hebbeln ◽  
Stephanie Kienast ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Water Column ◽  
North Atlantic ◽  
North Pacific ◽  
Isotopic Signature ◽  
Labrador Sea ◽  
Nitrate Sources ◽  
Baffin Bay ◽  
The North ◽  
The North Atlantic

<p>Subsurface nitrate in the Labrador Sea (NW Atlantic) and Baffin Bay is provided by North Pacific water flowing through Bering Strait and the Canadian Arctic as well as by advection from the North Atlantic. Both these nitrate sources are distinct in their isotopic signature (δ<sup>15</sup>N), owing to benthic denitrification on the Bering, Chukchi and east Siberian shelves and nitrogen fixation in the North Atlantic, respectively. Accordingly, water column profiles of δ<sup>15</sup>N<sub>(nitrate)</sub> collected off Greenland in the eastern Labrador Sea show low δ<sup>15</sup>N<sub>(nitrate)</sub>, which mixes with more <sup>15</sup>N-enriched nitrate flowing through Baffin Bay into the northern Labrador Sea. The Labrador Current carries this mixture southward along the western Labrador Sea, toward Newfoundland. The δ<sup>15</sup>N of surface sediments in the Labrador Sea closely mirrors these water column signals, suggesting that sediments can be used to trace changes in both the source signature of Atlantic versus Pacific-derived nitrate as well as in the admixture of the two source waters.</p><p>Two downcore sedimentary δ<sup>15</sup>N records from the NE and NW Labrador Sea coast both show high δ<sup>15</sup>N values of ca. 7‰ during the early Holocene (9-7 kyrs BP). In the NE Labrador Sea, this is followed by a long-term decrease toward δ<sup>15</sup>N of ca. 4.5‰ at the core top, in contrast to a much more subtle decrease in the NW Labrador Sea (surface sediment δ<sup>15</sup>N of ca. 6.5‰). The decreasing δ<sup>15</sup>N values along the eastern Labrador Sea are consistent with a Holocene increase in nitrogen fixation in the North Atlantic or an increasing advection of isotopically light nitrate. In turn, an increasing admixture of North-Pacific-derived nitrate, or intensified denitrification on the Bering Shelf would be required to explain the much subdued Holocene δ<sup>15</sup>N decrease in the NW Labrador Sea.</p>

scholarly journals Precursory atmospheric circulations with Rossby wave trains leading to Eurasian extreme cold events

2021 ◽  
Author(s):  
Wenqin zhuo ◽  
Fei Huang ◽  
Ruichang Ding ◽  
Jin Luo
Keyword(s):  
Rossby Wave ◽  
North Atlantic ◽  
Wave Train ◽  
Teleconnection Pattern ◽  
Boreal Winter ◽  
Formation Mechanisms ◽  
Baffin Bay ◽  
Atmospheric Circulations ◽  
Westerly Jet ◽  
Wave Trains

Abstract This work examines precursory atmospheric circulations with various wave trains contributing to extreme cooling over central Eurasia in boreal winter from 1979-2016 based on the ERA-Interim dataset. The empirical orthogonal function (EOF) method is used to classify the anomalous sea level pressure field averaged in two weeks prior to extreme cooling. Based on the classification, three types of precursory atmospheric circulation patterns are named according to the origins of wave trains, and their formation mechanisms are revealed as well . Type1: Baffin Bay-origin pattern, which forms in the downstream development of Rossby wave packets generated from the downward stratospheric energy transmission over the Baffin Bay. Type2: Pacific-origin pattern, similar to a Eurasian (EU) teleconnection pattern, arises at the exit area of the westerly jet in the central North Pacific where cyclonic shear exists; then it develops along the northerly westerly jet over the North Atlantic, which may act as a waveguide to the Eurasian continent. Type 3: Atlantic-origin, manifests as the negative phase of type 2, consistent with the Scandinavian (SCAND) pattern, which may results from the air-sea interaction induced by the warm anomaly of sea surface temperature in the middle of North Atlantic. In conclusion, the three types of precursory atmospheric wave train patterns that bring extreme cooling to Eurasia possess diverse disturbing sources and development mechanisms. The results, which are investigated based on a quasi-biweekly time scale , deepen our understanding of the atmospheric genesis of extreme weather and have specific indicative significance to improve the technique of extended forecast.

scholarly journals Can Regulation of Freshwater Runoff in Hudson Bay Affect the Climate of the North Atlantic?

ARCTIC ◽  
1996 ◽  
Vol 49 (4) ◽  
Author(s):  
Paul H. LeBlond ◽  
John R. Lazier ◽  
Andrew J. Weaver
Keyword(s):  
North Atlantic ◽  
Hudson Bay ◽  
Freshwater Runoff ◽  
The North ◽  
The North Atlantic
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