The Effects of Flowline Length Evolution on Chemistry-Delta O-18 Profiles from Penny Ice Cap, Baffin Island, Canada

The isotopic and chemical signatures for ice-age and Holocene ice from Summit, Greenland and Penny Ice Cap, Baffin Island, Canada, arc compared. The usual pattern of low delta(18)O, high Ca2+ and high Cl- is presented in the Summit records, but Penny Ice Cap has lower than present Cl- in its ice-age ice. A simple extension of the Hansson model (Hansson, 1994) is developed and used to simulate these signatures. The low ice-age Cl- from Penny Ice Cap is explained by having the ice-age ice originating many thousands of km inland near the centre of the Laurentide ice sheet and much further from the marine sources. Summit\u27s flowlines all start close to the present site. The Penny Ice Cap early-Holocene delta(18)O\u27s had to be corrected to offset the Laurentide meltwater distortion. The analysis suggests that presently the Summit and Penny Ice Cap marine impurity originates about,500 km away, and that presently Penny Ice Cap receives a significant amount of local continental impurity

Greenland and Canadian Arctic ice temperature profiles database

Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally available here for the first time. These newly available profiles, which are associated with pre-2010 boreholes, have been submitted by community members or digitized from published graphics and/or data tables. All 95 profiles are now made available in both absolute (meters) and normalized (0 to 1 ice thickness) depth scales and are accompanied by extensive metadata. These metadata include a transparent description of data provenance. The ice temperature profiles span 70 years, with the earliest profile being from 1950 at Camp VI, West Greenland. To highlight the value of this database in evaluating ice flow simulations, we compare the ice temperature profiles from the Greenland ice sheet with an ice flow simulation by the Parallel Ice Sheet Model (PISM). We find a cold bias in modeled near-surface ice temperatures within the ablation area, a warm bias in modeled basal ice temperatures at inland cold-bedded sites, and an apparent underestimation of deformational heating in high-strain settings. These biases provide process level insight on simulated ice temperatures

An ice-marginal δ18O record from Barnes Ice Cap, Baffin Island, Canada

Barnes Ice Cap, Baffin Island, Canada, is a remnant of the Laurentide ice sheet that separated from it about 8500 years ago. Owing to recession of the ice cap during the Holocene, Pleistocene-age ice is now exposed along the margin in a distinctive bubble-rich white band. δ180 variations across the white ice resemble those in Canadian Arctic ice cores, suggesting that Barnes Ice Cap preserves a climatic record through thelast glacial period, possibly reaching back into the previous (Sangamon) interglacial. The δ180 shift at the Wisconsin-Holocene transition (15 per mil) exceeds that in other Canadian and Greenland records and cannot be explained solely in climatic terms. A steady-state model reconstruction of the Laurentide ice sheet during the Last Glacial Maximum suggests that Late-glacial strata in Barnes Ice Cap originated high up ( >2400 m a.s.l.) and far "inland" on the ice sheet, along a ridge that extended between the ancestral Foxe and Keewatin ice domes

Calibration of an ice-core glaciochemical (sea salt) record with sea-ice variability in the Canadian Arctic. Annals of Glaciology 44

ABSTRACT. Correlation between glaciochemical time series from an ice core collected on Devon Ice Cap, Nunavut, Canada, and gridded time series of sea-ice concentrations reveals statistically significant inverse relationships between sea-salt concentrations (mainly Na +,Mg 2+ and Cl – ) in the ice core and sea-ice cover in Baffin Bay over the period 1980–97. An empirical orthogonal function (EOF) analysis performed on all major ions shows that the dominant mode of glaciochemical variability (EOF1) represents a sea-salt signal, which correlates best with sea-ice concentration in Baffin Bay. On a seasonal basis, the strongest and most spatially extensive anticorrelations are found in Baffin Bay during the fall, followed by spring, summer and winter. These results support the notion that increased openwater conditions in Baffin Bay during the stormy seasons (fall and spring) promote increased production, transport and deposition of sea-salt aerosols on Devon Ice Cap. Comparison of ice-core time series of EOF1, d 18 O and melt percentage, with air temperatures recorded in Upernavik, Greenland, suggests that ice-cover variations in Baffin Bay over the past �145 years were dynamically rather than thermodynamically controlled, with periods of strengthened cyclonic circulation leading to increased open-water conditions, and a greater sea-salt flux on Devon Ice Cap

A Holocene Record of Atmospheric Dust Deposition on the Penny Ice Cap, Baffin Island, Canada

An \u3e11,550-yr-long record of atmospheric dust deposition was developed from an ice core (P95) drilled through the Penny ice cap, Baffin Island. The P95 record documents environmental changes that affected the production and transport of dust in the eastern Canadian Arctic during the late Pleistocene and Holocene. Dust deposition on the Penny ice cap was greatest in late-glacial time when the climate was dry and windy and comparatively low in the Holocene. Microparticles deposited during late-glacial time are finer than in Greenland cores, suggesting distinct dust sources and transport trajectories to each region. Dust deposition at the P95 site increased after ca. 7800 yr ago as the Penny ice cap receded and distance from local dust sources was reduced. Deflation of newly exposed marine sediments on southwestern Baffin Island may have contributed to this dust increase. The P95 and GISP2 (Greenland) dust records show diverging trends in the middle to late Holocene, reflecting the growing influence of regional environmental conditions (e.g., dust source area, snow cover extent) on atmospheric dust deposition. This study further demonstrates how valuable records of regional-scale paleoenvironmental changes can be developed from small circum-Arctic ice caps, even those affected by considerable melt

Calibration of an ice-core glaciochemical (sea-salt) record with sea-ice variability in the Canadian Arctic

Correlation between glaciochemical time series from an ice core collected on Devon Ice Cap, Nunavut, Canada, and gridded time series of sea-ice concentrations reveals statistically significant inverse relationships between sea-salt concentrations (mainly Na+, Mg2+ and Cl−) in the ice core and sea-ice cover in Baffin Bay over the period 1980–97. An empirical orthogonal function (EOF) analysis performed on all major ions shows that the dominant mode of glaciochemical variability (EOF1) represents a sea-salt signal, which correlates best with sea-ice concentration in Baffin Bay. On a seasonal basis, the strongest and most spatially extensive anticorrelations are found in Baffin Bay during the fall, followed by spring, summer and winter. These results support the notion that increased open-water conditions in Baffin Bay during the stormy seasons (fall and spring) promote increased production, transport and deposition of sea-salt aerosols on Devon Ice Cap. Comparison of ice-core time series of EOF1, 18O and melt percentage, with air temperatures recorded in Upernavik, Greenland, suggests that ice-cover variations in Baffin Bay over the past ∼145 years were dynamically rather than thermodynamically controlled, with periods of strengthened cyclonic circulation leading to increased open-water conditions, and a greater sea-salt flux on Devon Ice Cap