scholarly journals Influence of the Arctic Circumpolar Vortex on the Mass Balance of Canadian High Arctic Glaciers

2007 ◽  
Vol 20 (18) ◽  
pp. 4586-4598 ◽  
Author(s):  
Alex S. Gardner ◽  
Martin Sharp
Keyword(s):  
Mass Balance ◽  
Regime Shift ◽  
High Arctic ◽  
Western Hemisphere ◽  
The Arctic ◽  
Glacier Mass Balance ◽  
Canadian High Arctic ◽  
Circumpolar Vortex ◽  
Eastern Hemisphere ◽  
Air Temperatures

Abstract Variability in July mean surface air temperatures from 1963 to 2003 accounted for 62% of the variance in the regional annual glacier mass balance signal for the Canadian High Arctic. A regime shift to more negative regional glacier mass balance occurred between 1986 and 1987, and is linked to a coincident shift from lower to higher mean July air temperatures. Both the interannual changes and the regime shifts in regional glacier mass balance and July air temperatures are related to variations in the position and strength of the July circumpolar vortex. In years when the July vortex is “strong” and its center is located in the Western Hemisphere, positive mass balance anomalies prevail. In contrast, highly negative mass balance anomalies occur when the July circumpolar vortex is either weak or strong without elongation over the Canadian High Arctic, and its center is located in the Eastern Hemisphere. The occurrence of westerly positioned July vortices has decreased by 40% since 1987. The associated shift to a dominantly easterly positioned July vortex was associated with an increased frequency of tropospheric ridging over the Canadian High Arctic, higher surface air temperatures, and more negative regional glacier mass balance.

scholarly journals Multiphase formation of superimposed ice during a mass-balance year at a maritime high-Arctic glacier

2002 ◽  
Vol 48 (163) ◽  
pp. 545-551 ◽  
Author(s):  
Jemma L. Wadham ◽  
Anne-Marie Nuttall
Keyword(s):  
Mass Balance ◽  
High Arctic ◽  
Ice Formation ◽  
Glacier Mass Balance ◽  
Climatic Warming ◽  
Arctic Regions ◽  
Air Temperatures ◽  
Arctic Glacier ◽  
Second Period ◽  
Snow Temperature

AbstractMeteorological and snow-temperature data from midtre Lovénbreen, Spitsbergen, Svalbard, indicate two distinct annual phases of rapid snowpack warming and superimposed-ice formation in 1998/99. Short periods of positive air temperatures in early winter, lasting up to 36 hours and often coinciding with rainfall, caused rapid glacier-wide melting. Percolating water froze to form superimposed ice on the lower half of the glacier, and wetted–refrozen snow and ice lenses at higher altitudes. The second period of superimposed-ice formation commenced in May/June 1999 and continued for 5 weeks at low altitudes and throughout the summer at high altitudes. These observations at midtre Lovénbreen are typical of Spitsbergen glaciers and reflect the unique climatology of the region. They contrast with those from glaciers in more continental climatic settings where superimposed-ice formation is confined to a single period during summer. There are significant implications for glacier mass balance, with superimposed ice locally comprising up to 20% of winter balances and accounting for ∼16–25% of the annual accumulation. Since projected climatic warming is greatest during the winter months in Arctic regions, superimposed ice may become an increasingly important component of the winter, and potentially the net, balance of Spitsbergen glaciers.

scholarly journals A trajectory analysis of atmospheric transport of black carbon aerosols to Canadian High Arctic in winter and spring (1990–2005)

2010 ◽  
Vol 10 (2) ◽  
pp. 2221-2244 ◽  
Author(s):  
L. Huang ◽  
S. L. Gong ◽  
S. Sharma ◽  
D. Lavoué ◽  
C. Q. Jia
Keyword(s):  
Regression Model ◽  
Black Carbon ◽  
North American ◽  
Emission Intensity ◽  
Atmospheric Transport ◽  
High Arctic ◽  
The Arctic ◽  
Canadian High Arctic ◽  
Near Surface ◽  
Annual Variations

Abstract. Black carbon (BC) particles accumulated in the Arctic troposphere and deposited over snow have significant effects on radiative forcing of the Arctic regional climate. Applying cluster analysis technique on 10-day backward trajectories, transport pathways affecting Alert (82.5° N, 62.5° W), Nunavut in Canada are identified in this work, along with the associated transport frequency. Based on the atmospheric transport frequency and the estimated BC emission intensity from surrounding regions, a linear regression model is constructed to investigate the inter-annual variations of BC observed at Alert in January and April, representative of winter and spring respectively, between 1990 and 2005. Strong correlations are found between BC concentrations predicted with the regression model and measured at Alert for both seasons (R2 equals 0.77 and 0.81 for winter and spring, respectively). Results imply that atmospheric transport and BC emission are the major contributors to the inter-annual variations in BC concentrations observed at Alert in the cold seasons for the 16-year period. Based on the regression model the relative contributions of regional BC emissions affecting Alert are attributed to the Eurasian sector, composed of the European Union and the former USSR, and the North American sector. Considering both seasons, the model suggests that Eurasia is the major contributor to the near-surface BC levels at the Canadian High Arctic site with an average contribution of over 85% during the 16-year period. In winter, the atmospheric transport of BC aerosols from Eurasia is found to be even more predominant with a multi-year average of 94%. The model estimates smaller contribution from the Eurasian sector in spring (70%) than that in winter. It is also found that the change in Eurasian contributions depends mainly on the reduction of emission intensity, while the changes in both emission and atmospheric transport contributed to the inter-annual variation of North American contributions.

scholarly journals Dynamics of Ice-Island Motion Near the Coast of Axel Heiberg Island, Canadian High Arctic

1989 ◽  
Vol 12 ◽  
pp. 152-156 ◽  
Author(s):  
W.M. Sackinger ◽  
M.O. Jeffries ◽  
H. Tippens ◽  
F. Li ◽  
M. Lu
Keyword(s):  
Surface Wind ◽  
High Arctic ◽  
The Arctic ◽  
Movement Direction ◽  
Canadian High Arctic ◽  
North West ◽  
The North ◽  
Pack Ice ◽  
Axel Heiberg Island ◽  
Ice Force

The largest ice island presently known to exist in the Arctic Ocean has a mass of about 700 × 106 tonnes, an area of about 26 km2, and a mean thickness of 42.5 m. Known as Hobson’s Ice Island, this large ice feature has been tracked almost continuously since August 1983 with a succession of Argos buoys. In this paper, two particular ice-island movement episodes near the north-west coast of Axel Heiberg Island are described: 6–16 May 1986 and 14–21 June 1986. Each movement episode is analyzed in terms of the forces acting on the ice island, including wind shear, water drag, water shear, Coriolis force, sea-surface tilt, and pack-ice force. Ice-island movement is generally preceded by an offshore surface wind, and a threshold wind speed of 6 m s°1 appears to be necessary to initiate ice-island motion. An angle of 50° between surface wind and ice-island movement direction is noted during one episode. The pack-ice force, which appears to be the dominant arresting factor of ice-island motion for these two episodes, varies from 100° to 180° to the left of the ice-island velocity direction, depending upon whether the ice island is accelerating or decelerating.

scholarly journals Equilibrium-Line Altitudes, Mass Balance, and July Freezing-Level Heights in the Canadian High Arctic

1975 ◽  
Vol 14 (71) ◽  
pp. 267-274 ◽  
Author(s):  
R. S. Bradley
Keyword(s):  
Mass Balance ◽  
High Arctic ◽  
Equilibrium Line ◽  
Canadian High Arctic ◽  
North West ◽  
Freezing Level ◽  
Ice Cap ◽  
The North ◽  
Devon Ice Cap ◽  
Axel Heiberg Island

Equilibrium-line altitudes on the White Glacier, Axel Heiberg Island, and the north-west sector of the Devon Ice Cap are shown to be closely related to mean July freezing-level heights at nearby upper-air weather stations. An inverse relationship between July freezing-level heights and mass balance on the Devon Ice Cap is also shown. Reasons for such correlations are suggested and some limitations of the relationship are outlined. Recent lowering of the freezing level in July is discussed in relation to the theoretical “steady-state” equilibrium-line altitudes in the Canadian high Arctic. It is suggested that positive mass-balance years have predominated over a large part of northern Ellesmere Island and north-central Axel Heiberg Island since 1963, and some glaciological evidence supporting this hypothesis is given.

scholarly journals Calculation of Mass Balance of Glaciers by Remote-Sensing Imagery Using Similarity of Accumulation and Ablation Isoline Patterns

1987 ◽  
Vol 33 (115) ◽  
pp. 363-368 ◽  
Author(s):  
A.N Krenke ◽  
V.M Menshutin
Keyword(s):  
Remote Sensing ◽  
Mass Balance ◽  
Satellite Imagery ◽  
Equilibrium Line ◽  
Glacier Mass Balance ◽  
Specific Mass ◽  
Mean Values ◽  
Remote Sensing Imagery ◽  
Air Temperatures ◽  
One Year

Abstract An investigation of the combined heat, ice, and water balances was carried out in the Marukh glacier basin (west Caucasus) in 1966–67 to 1976–77, according to the International Hydrological Decade programme. Averaged glacier mass balance for these 11 years appears to be −55 g cm−2 year−1 according to stake measurements, and −51 g cm−2 year−1 according to geodetic measurements. The variability of accumulation is estimated as C v = 0.15 and of ablation as C v = 0.11. Thus, the variation in accumulation governs the oscillations in glacier balance. The inner nourishment of the glacier was also taken into account. The glacier mass balance is closely related to the relation between the accumulation and ablation areas. The “transient” values of both figures during the whole period of ablation can be used for this relation. The forms of the accumulation and ablation fields are similar from year to year and from one 10 day period to another. The areas of the accumulation and ablation zones are very different from one year to another. On the contrary, the average specific balance for each zone changes very little. One can use these features for the construction of accumulation, ablation, and specific mass-balance maps from satellite imagery. Mean values for the mass-balance terms occur in the vicinity of the equilibrium line. They can be calculated by using the air temperatures. Deviations from the means in different areas of the glacier determine the typical fields of the mass-balance terms.

scholarly journals Changes in Eurasian glaciation during the past century: glacier mass balance and ice-core evidence

1997 ◽  
Vol 24 ◽  
pp. 283-287 ◽  
Author(s):  
Vladimir N. Mikhalenko
Keyword(s):  
Mass Balance ◽  
Ice Core ◽  
Climatic Conditions ◽  
Tien Shan ◽  
The Arctic ◽  
Past Century ◽  
Glacier Mass Balance ◽  
The Past ◽  
Ice Cap ◽  
Glacier Ice

Glaciers of both the Arctic and mid-latitude mountain systems within Eurasia have retreated intensively during the past century. Measured and reconstructed glacier mass balances show that glacier retreat began around the 1880s. The mean annual mass-balance value for 1880–1990 was −480 mm a−1 for glaciers with maritime climatic conditions, and −140 mm a−1 for continental glaciers. It can be concluded that warming in the Caucasus occurred during at least the last 60 years, according to the distribution of crystal sizes in an ice core from the Dzhantugan firn plateau. Temperatures measured in 1962 at 20 m on the Gregoriev ice cap, Tien Shan, were −4.2°C while in 1990 they were −2°C, a warming of 2.2°C over 28 years. Changes in the isotopic composition of glacier ice during the 20th century indicate recent and continuing warming in different regions of Eurasia. The δ18O records reveal an enrichment at the Gregoriev ice cap during the last 50 years, while surface temperatures at the Tien Shan meteorological station have increased 0.5°C since 1930.

Changes in the 300-mb North Circumpolar Vortex, 1963–2001

2006 ◽  
Vol 19 (12) ◽  
pp. 2984-2994 ◽  
Author(s):  
James K. Angell
Keyword(s):  
El Niño ◽  
El Nino ◽  
Western Hemisphere ◽  
Quasi Biennial Oscillation ◽  
Circumpolar Vortex ◽  
Eastern Hemisphere ◽  
University Of Berlin ◽  
El Chichón ◽  
Vortex Size ◽  
El Chichon

Abstract The mean monthly polar stereographic map analyses of the Free University of Berlin terminated at the end of 2001. This paper summarizes the changes in size of the 300-mb north circumpolar vortex, and quadrants, for the full period of record, 1963–2001, where the size has been defined by planimetering the area poleward of contours in the jet stream core. A contracted vortex has tended to be a deep vortex in winter but a shallow vortex in summer. During 1963–2001 there was a statistically significant decrease in vortex size of 1.5% per decade, the decrease in size of Western Hemisphere quadrants being twice that of Eastern Hemisphere quadrants. A significant increase in Arctic Oscillation (AO) index accompanies the significant decrease in vortex size, but since the vortex contracts appreciably in all four seasons, whereas the positive trend in the AO index is mainly in winter, the vortex cannot serve as a proxy for the AO index. The evidence for vortex contraction at the time of the 1976–77 regime shift is not conclusive, but there is good evidence for a 6% increase in vortex size due to the 1991 Pinatubo eruption. There is little change in vortex size following the 1982 El Chichon eruption, however. Because on average there is a significant 4% contraction of the vortex following an El Niño, it is proposed that the vortex expansion to be expected following the 1982 El Chichon eruption has been contravened by the contraction following the strong 1982–83 El Niño. There is little relation between vortex size and phase of the quasi-biennial oscillation (QBO), and the evidence for a contracted vortex near 11-yr sunspot maxima is tenuous because the vortex record extends through only three full sunspot cycles. There is a highly significant tendency for opposite vortex quadrants 0°–90°E and 90°W–180° to vary in size together, indicating either a pulsating polar vortex or the propagation of planetary wavenumber 2.

scholarly journals Relationships between interannual variability of glacier mass balance and climate

1999 ◽  
Vol 45 (151) ◽  
pp. 456-462 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Yu Zhang
Keyword(s):  
Standard Deviation ◽  
Mass Balance ◽  
Interannual Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Glacier Mass Balance ◽  
Strongly Correlated ◽  
Calculated Mass ◽  
The Difference

AbstractThe interannual variability of glacier mass balance is expressed by the standard deviation of net balance, which varies from about ±0.1 to ±1.4 m a−1for a sample of 115 glaciers with at least 5 years of record. The standard deviation of net balance is strongly correlated with the mass-balance amplitude (half the difference between winter and summer balances) for 60 glaciers, so the amplitude can be estimated from net balance standard deviation for the other 55 glaciers where winter and summer balances are unavailable. The observed and calculated mass-balance amplitudes for the 115 glaciers show contrasts between the Arctic and lower latitudes, and between maritime and continental regions. The interannual variability of mass balance means that balances must be measured for at least a few years to determine a statistically reliable mean balance for any glacier. The net balance of the Greenland ice sheet is still not accurately known, but its standard deviation is here estimated to be about ±0.24 m a−1, in agreement with other Arctic glaciers. Mass-balance variability of this magnitude implies that the ice sheet can thicken or thin by several metres over 20–30 years without giving statistically significant evidence of non-zero balance under present climate.

scholarly journals Factors influencing the basal temperatures of a High Arctic polythermal glacier

2009 ◽  
Vol 50 (52) ◽  
pp. 9-16 ◽  
Author(s):  
Trudy Wohlleben ◽  
Martin Sharp ◽  
Andrew Bush
Keyword(s):  
Thermal Characteristics ◽  
High Arctic ◽  
Ice Thickness ◽  
Temperature Model ◽  
Canadian High Arctic ◽  
Basal Ice ◽  
Air Temperatures ◽  
Modelling Studies ◽  
Pressure Melting ◽  
Polythermal Glacier

AbstractA number of glaciers in the Canadian High Arctic are composed primarily of cold ice, but the ice at or near their beds reaches the pressure-melting point (PMP) in the ablation zone. Past modelling studies have suggested that the basal temperatures of some of these glaciers reach the PMP where they should not, indicating that they are not in thermal equilibrium with present-day surface air temperatures. To investigate the possible reasons for thermal disequilibria in such glaciers, a two-dimensional ice temperature model was used to simulate the inferred thermal characteristics of John Evans Glacier, Ellesmere Island. Results indicate that while surface refreezing and historical ice-thickness changes have had a warming effect upon basal ice temperatures, supraglacial meltwater reaching the glacier bed provides the single most critical heat source for explaining the apparent thermal disequilibrium between present-day inferred ice–bed temperatures and those modelled under present-day boundary conditions.

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