scholarly journals The Mass Balance of the Devon Island Ice Cap, Northwest Territories, Canada, 1961-66

1970 ◽  
Vol 9 (57) ◽  
pp. 325-336 ◽  
Author(s):  
R.M. Koerner
Keyword(s):  
Mass Balance ◽  
Equilibrium Line ◽  
Accumulation Pattern ◽  
North West ◽  
Average Value ◽  
Devon Island ◽  
Ice Cap ◽  
The North ◽  
West Part ◽  
The Mean

Methods used in measuring the mass balance of the Devon Island ice cap are described. The use of dyes and melt trays is recommended in the superimposed-ice and firn zones of sub-polar glaciers. The north-west part of the ice cap was studied in most detail and has had a slightly negative net balance for the period 1961-66. An inverse relationship between mean net balance(bn)and elevation of the equilibrium line in the north-west part of the ice cap indicates that the mean net balance there would be zero with an equilibrium line at 920 m (±80 m) elevation. Accumulation on the ice cap is greatest in the south-east but the measurements suggest that the mean net balance there is similar to the mean net balance on the rest of the ice cap. It is concluded that the present accumulation pattern must have existed for several hundreds, and possibly thousands of years. A study of firn stratigraphy and of variations in the elevation of the firn and equilibrium lines indicates that between 1961 and 1966 only 1962 had a more negative mean net balance than the average value for the period 1934-60. During the same 26 year period the net balance at 1 787 m elevation has varied, but summer conditions do not appear to have changed significantly.

scholarly journals The Mass Balance of the Devon Island Ice Cap, Northwest Territories, Canada, 1961-66

1970 ◽  
Vol 9 (57) ◽  
pp. 325-336 ◽  
Author(s):  
R.M. Koerner
Keyword(s):  
Mass Balance ◽  
Equilibrium Line ◽  
Accumulation Pattern ◽  
North West ◽  
Average Value ◽  
Devon Island ◽  
Ice Cap ◽  
The North ◽  
West Part ◽  
The Mean

Methods used in measuring the mass balance of the Devon Island ice cap are described. The use of dyes and melt trays is recommended in the superimposed-ice and firn zones of sub-polar glaciers. The north-west part of the ice cap was studied in most detail and has had a slightly negative net balance for the period 1961-66. An inverse relationship between mean net balance (bn) and elevation of the equilibrium line in the north-west part of the ice cap indicates that the mean net balance there would be zero with an equilibrium line at 920 m (±80 m) elevation. Accumulation on the ice cap is greatest in the south-east but the measurements suggest that the mean net balance there is similar to the mean net balance on the rest of the ice cap. It is concluded that the present accumulation pattern must have existed for several hundreds, and possibly thousands of years. A study of firn stratigraphy and of variations in the elevation of the firn and equilibrium lines indicates that between 1961 and 1966 only 1962 had a more negative mean net balance than the average value for the period 1934-60. During the same 26 year period the net balance at 1 787 m elevation has varied, but summer conditions do not appear to have changed significantly.

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 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

AbstractEquilibrium-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 A mean net accumulation pattern derived from radioactive layers and radar soundings on Austfonna, Nordaustlandet, Svalbard

2001 ◽  
Vol 47 (159) ◽  
pp. 555-566 ◽  
Author(s):  
Jean Francis Pinglot ◽  
Jon Ove Hagen ◽  
Kjetil Melvold ◽  
Trond Eiken ◽  
Christian Vincent
Keyword(s):  
Mass Balance ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Equilibrium Line ◽  
Accumulation Pattern ◽  
Ice Cap ◽  
The Mean ◽  
Nuclear Tests ◽  
Ground Penetrating ◽  
High Degree

AbstractWe present the snow-accumulation distribution over Austfonna, Nordaustlandet, Svalbard, based on 29 shallow ice cores that were retrieved from this ice cap during 1998 and 1999. Mean annual net accumulation is deduced from radioactive layers resulting from the 1954–74 atmospheric nuclear tests (maximum in 1963) and the Chernobyl accident (1986). The Chernobyl layer was located in 19 ice cores in the accumulation area, and the nuclear test layer was located in two deeper ice cores. In addition, the spatial variation of the depth of winter 1998/99 snowpack was mapped using snow probing, ground-penetrating radar methods and pit studies. The altitudinal gradient of the mean annual net mass balance and the altitude of the mean equilibrium line are determined along five transects ending at the top of the ice cap. The mean annual net mass balance and the equilibrium-line altitudes show a high degree of asymmetry between the western and eastern parts of Austfonna, in accordance with the distribution of winter accumulation. Large interannual variations of the accumulation exist. However, the study of the mean annual net mass balance shows no trend for two different time periods, 1963–86 and 1986 to the date of the drillings (1998/99).

scholarly journals Accumulation on the Devon Island Ice Cap, Northwest Territories, Canada

1966 ◽  
Vol 6 (45) ◽  
pp. 383-392 ◽  
Author(s):  
R. M. Koerner
Keyword(s):  
Open Water ◽  
Cyclonic Activity ◽  
High Accumulation ◽  
Accumulation Pattern ◽  
Baffin Bay ◽  
North West ◽  
Devon Island ◽  
Ice Cap ◽  
The North ◽  
Snow Transport

The pattern of accumulation on the Devon Island ice cap is described. There is an area of minimum accumulation encircling the highest part of the ice cap and 100–200 m. below it. Below this zone, accumulation gradually increases to a maximum near the ice-cap edge. The overall pattern is related to snow transport by katabatic winds. There is a regional accumulation pattern of high accumulation (ca. 40.0 cm. water equivalent) in the south-east part of the ice cap and an area of low accumulation (ca. 11 0 cm. water equivalent) in the north-west. This east-south-east to west-north-west accumulation gradient is related to cyclonic activity to the east in Baffin Bay, and it is probably intensified by the presence of open water in the same area.

scholarly journals Accumulation on the Devon Island Ice Cap, Northwest Territories, Canada

1966 ◽  
Vol 6 (45) ◽  
pp. 383-392 ◽  
Author(s):  
R. M. Koerner
Keyword(s):  
Open Water ◽  
Cyclonic Activity ◽  
High Accumulation ◽  
Accumulation Pattern ◽  
Baffin Bay ◽  
North West ◽  
Devon Island ◽  
Ice Cap ◽  
The North ◽  
Snow Transport

The pattern of accumulation on the Devon Island ice cap is described. There is an area of minimum accumulation encircling the highest part of the ice cap and 100–200 m. below it. Below this zone, accumulation gradually increases to a maximum near the ice-cap edge. The overall pattern is related to snow transport by katabatic winds. There is a regional accumulation pattern of high accumulation (ca. 40.0 cm. water equivalent) in the south-east part of the ice cap and an area of low accumulation (ca. 11 0 cm. water equivalent) in the north-west. This east-south-east to west-north-west accumulation gradient is related to cyclonic activity to the east in Baffin Bay, and it is probably intensified by the presence of open water in the same area.

scholarly journals Studies of Englacial Profiles in the Lake Hazen Area of Northern Ellesmere Island

1960 ◽  
Vol 3 (27) ◽  
pp. 610-625
Author(s):  
G. Hattersley-Smith
Keyword(s):  
Crystal Structure ◽  
Budget Deficit ◽  
Ice Core ◽  
Ellesmere Island ◽  
Equilibrium Line ◽  
Mean Annual Temperature ◽  
The Past ◽  
Ice Cap ◽  
The North ◽  
The Mean

AbstractGlaciological research on the ice cap to the north of Lake Hazen in northern Ellesmere Island was one of the main objectives of the Canadian I.G.Y. expedition to this area in 1957–1958. The method of nourishment of this ice cap and of Gilman Glacier, one of its southward-flowing outlets, was studied in pit and bore hole profiles above and below the equilibrium line, which was found at an elevation of about 1,200 m. Between an elevation of about 1,450 and 2,000 m. accumulation is by firn formation, while between about 1,280 and 1,450 m. interfingering of firn and superimposed ice occurs. At 1,800 m. the mean annual accumulation over the past twenty years is estimated as 12.8 g. cm.–2. On Gilman Glacier below the equilibrium line variations in density and crystal structure in an ice core to a depth of 25 m. are seen to depend on the proportion of firn to superimposed ice formed during accumulation. These variations correspond to past changes in the position of the equilibrium line. Englacial temperature measurements indicate a mean annual temperature of about –18.5° C. at an elevation of 1 ,040 m. A budget deficit for Gilman Glacier during two years of observations may be related to the increased summer melting of the last 20 years, deduced from pit studies at 1,800 m.

A method for monitoring glacier mass balance using satellite albedo measurements: application to Vatnajökull, Iceland

2002 ◽  
Vol 48 (161) ◽  
pp. 267-278 ◽  
Author(s):  
Martijn S. De Ruyter De Wildt ◽  
Johannes Oerlemans ◽  
Helgi Björnsson
Keyword(s):  
Mass Balance ◽  
Surface Albedo ◽  
Global Radiation ◽  
Winter Precipitation ◽  
Equilibrium Line ◽  
Gradual Transition ◽  
Glacier Mass Balance ◽  
Ice Cap ◽  
The Mean ◽  
Melting Season

AbstractWe compare satellite albedo images of Vatnajökull, Iceland, with mass-balance measurements for the years 1991–99. We find that the equilibrium line is mostly not visible when it is located above its position of the previous year(s). Equilibrium-line detection is further hindered by clouds and a gradual transition between ice and firn or snow. Consequently, firn-line elevation at the end of the melting season is not particularly useful for estimating the annual mass balance. Instead, we propose to study the mean albedo of the entire ice cap throughout the melting season so that all available information about the surface albedo is taken into account. The mean net potential global radiation, which can be estimated from the mean surface albedo alone, both depends on and influences summer melt. It also depends on winter precipitation and, integrated over the melting season, is found to relate linearly to the specific mass balance B (r = 0.87 and 0.94 for different outlets of Vatnajökull). B can be estimated quantitatively when this relation is known and qualitatively when it is not. The uncertainty in the satellite-derived value of B is 0.5–0.8 m w.e., which for Vatnajökull corresponds to about 27% of the interannual variability of B.

scholarly journals Studies of Englacial Profiles in the Lake Hazen Area of Northern Ellesmere Island

1960 ◽  
Vol 3 (27) ◽  
pp. 610-625 ◽  
Author(s):  
G. Hattersley-Smith
Keyword(s):  
Crystal Structure ◽  
Budget Deficit ◽  
Ice Core ◽  
Ellesmere Island ◽  
Equilibrium Line ◽  
Mean Annual Temperature ◽  
The Past ◽  
Ice Cap ◽  
The North ◽  
The Mean

AbstractGlaciological research on the ice cap to the north of Lake Hazen in northern Ellesmere Island was one of the main objectives of the Canadian I.G.Y. expedition to this area in 1957–1958. The method of nourishment of this ice cap and of Gilman Glacier, one of its southward-flowing outlets, was studied in pit and bore hole profiles above and below the equilibrium line, which was found at an elevation of about 1,200 m. Between an elevation of about 1,450 and 2,000 m. accumulation is by firn formation, while between about 1,280 and 1,450 m. interfingering of firn and superimposed ice occurs. At 1,800 m. the mean annual accumulation over the past twenty years is estimated as 12.8 g. cm.–2. On Gilman Glacier below the equilibrium line variations in density and crystal structure in an ice core to a depth of 25 m. are seen to depend on the proportion of firn to superimposed ice formed during accumulation. These variations correspond to past changes in the position of the equilibrium line. Englacial temperature measurements indicate a mean annual temperature of about –18.5° C. at an elevation of 1 ,040 m. A budget deficit for Gilman Glacier during two years of observations may be related to the increased summer melting of the last 20 years, deduced from pit studies at 1,800 m.

CURRENT STATE AND DEVELOPMENT PERSPECTIVES OF THE CASPIAN SPRAT FISHERIES

2018 ◽  
pp. 69-75
Author(s):  
Tatiana Vasilievna Pomogaeva ◽  
Aliya Ahmetovna Aseinova ◽  
Yuriy Aleksandrovich Paritskiy ◽  
Vjacheslav Petrovich Razinkov
Keyword(s):  
Food Item ◽  
Growth Potential ◽  
North West ◽  
Marine Fishery ◽  
The North ◽  
Current State ◽  
West Part ◽  
Eggs And Larvae ◽  
Intensive Growth

The article presents annual statistical data of the Caspian Research Institute of Fishery. There has been kept track of the long term dynamics of the stocks of three species of Caspian sprat (anchovy, big-eyed kilka, sprat) and investigated a process of substituting a food item of sprats Eurytemora grimmi to a small-celled copepod species Acartia tonsa Dana. According to the research results, there has been determined growth potential of stocks of each species. Ctenophoran-Mnemiopsis has an adverse effect on sprat population by eating fish eggs and larvae. Ctenophoram - Mnemiopsis is a nutritional competitor to the full-grown fishes. The article gives recommendations on reclamation of stocks of the most perspective species - common sprat, whose biological characteristics helped not to suffer during Ctenophoram outburst and to increase its population during change of the main food item. Hydroacoustic survey data prove the intensive growth of common sprat biomass in the north-west part of the Middle Caspian. According to the results of the research it may be concluded that to realize the volumes of recommended sprat catch it is necessary to organize the marine fishery of common sprat at the Russian Middle Caspian shelf.

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