scholarly journals Accumulation Characteristics on a Cold, High-Alpine Firn Saddle from a Snow-Pit Study on Colle Gnifetti, Monte Rosa, Swiss Alps

1983 ◽  
Vol 29 (102) ◽  
pp. 260-271 ◽  
Author(s):  
W. Haeberli ◽  
U. Schotterer ◽  
D. Wagenbach ◽  
H. Haeberli Schwitter ◽  
S. Bortenschlager
Keyword(s):  
Electrical Conductivity ◽  
Strong Influence ◽  
Early Summer ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Surface Layers ◽  
Place Of Origin ◽  
Monte Rosa ◽  
Accumulation Characteristics ◽  
Sedimentation Processes

AbstractIn a snow pit, incorporating about 2.5 a of accumulation, on the 4 450 m high Colle Gnifetti, Monte Rosa, various snow characteristics, isotopes (δ18O, 3H), electrical conductivity, dust, trace elements, and pollen were investigated. The aim of this study was to develop a key for the stratigraphic interpretation of cores from cold, high-alpine firn areas. It appears that the strong influence of wind results in mixing and re-sedimentation processes in the surface layers. Nevertheless, by interpreting several parameters in a combined way, it is possible to classify a large number of the layers according to their season and sometimes to their place of origin. Apart from the melt layers, which only appear in early summer to summer layers, other prominent features are the (Saharan) dust falls, characterized by dust and conductivity peaks.

scholarly journals Accumulation Characteristics on a Cold, High-Alpine Firn Saddle from a Snow-Pit Study on Colle Gnifetti, Monte Rosa, Swiss Alps

1983 ◽  
Vol 29 (102) ◽  
pp. 260-271 ◽  
Author(s):  
W. Haeberli ◽  
U. Schotterer ◽  
D. Wagenbach ◽  
H. Haeberli Schwitter ◽  
S. Bortenschlager
Keyword(s):  
Electrical Conductivity ◽  
Strong Influence ◽  
Early Summer ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Surface Layers ◽  
Place Of Origin ◽  
Monte Rosa ◽  
Accumulation Characteristics ◽  
Sedimentation Processes

Abstract In a snow pit, incorporating about 2.5 a of accumulation, on the 4 450 m high Colle Gnifetti, Monte Rosa, various snow characteristics, isotopes (δ 18O, 3H), electrical conductivity, dust, trace elements, and pollen were investigated. The aim of this study was to develop a key for the stratigraphic interpretation of cores from cold, high-alpine firn areas. It appears that the strong influence of wind results in mixing and re-sedimentation processes in the surface layers. Nevertheless, by interpreting several parameters in a combined way, it is possible to classify a large number of the layers according to their season and sometimes to their place of origin. Apart from the melt layers, which only appear in early summer to summer layers, other prominent features are the (Saharan) dust falls, characterized by dust and conductivity peaks.

scholarly journals Seasonal evolution of aerosol stratigraphy in Ürümqi glacier No. 1 percolation zone, eastern Tien Shan, China

2006 ◽  
Vol 43 ◽  
pp. 245-249 ◽  
Author(s):  
Feiteng Wang ◽  
Zhongqin Li ◽  
Xiaoni You ◽  
Chuanjin Li ◽  
Huilin Li ◽  
...  
Keyword(s):  
Wind Erosion ◽  
Sampling Site ◽  
Chemical Species ◽  
Early Summer ◽  
Tien Shan ◽  
Wet Season ◽  
Surface Layers ◽  
Different Depths ◽  
Physical And Chemical ◽  
Percolation Zone

AbstractThe processes involved in the evolution of vertical profiles of Mg2+, Ca2+ and microparticle concentrations, as well as their seasonal variation in surface snow, were studied by weekly sampling from September 2003 to September 2004 of a snow pit on Ürümqi glacier No. 1, eastern Tien Shan, China. The development of the microparticle and Mg2+ and Ca2+ stratigraphy in the snow pit is closely related to the physical development of the snow–firn pack. The sampling site is located at 4130 ma.s.l. in the percolation zone of the glacier, and in addition to the effects of sublimation and wind erosion, melting plays a crucial role in both the physical and chemical evolution processes. During the winter, soluble aerosol concentrations in the surface layers are altered slightly by sublimation and wind erosion, and the concentrations are further modified as the wet season begins in late April. In contrast, soluble aerosol stratigraphy in the deeper layers remains relatively unchanged through the winter. In early summer, as melting occurs in the upper part of the snow–firn pack, meltwater carries chemical species to different depths in the underlying snow–firn layers, such that at the end of the ablation season, all of the surface cations might be leached out from the upper layers. In addition, the possible source of calcium and magnesium is discussed in this paper.

scholarly journals Salinity Status of Lajas Valley Soils

1969 ◽  
Vol 41 (1) ◽  
pp. 25-34
Author(s):  
Juan A. Bonnet ◽  
Eduardo J. Brenes
Keyword(s):  
Electrical Conductivity ◽  
Hydraulic Conductivity ◽  
Soil Layer ◽  
Soil Surface ◽  
Exchangeable Sodium Percentage ◽  
Exchangeable Sodium ◽  
Surface Layers ◽  
Alkali Soils ◽  
The World ◽  
Sodium Percentage

1. The area of soils surveyed in Lajas Valley was 24,656 acres. 2. The soils were classified into normal, saline, saline-alkali, and non- saline-alkali at depths of 0 to 8, 8 to 24, 24 to 48, and 48 to 72 inches, respectively. 3. A large percentage of normal soils was found in the upper soil layer and of saline-alkali soils in the lower layers. 4. Normal soils occupied about 86 percent of the surface area to a depth of 8 inches and about 63 percent at a depth of 8 to 24 inches. 5. Soils with a salinity problem increased from 9 percent at a depth of 8 inches to 28.3, 58.8 and 68.5 percent, respectively, at depths of 8 to 24, 24 to 48, and 48 to 72 inches. 6. The soils with a salinity problem were largely of the saline-alkali class. 7. In four soil-profile samples taken from Lajas Valley, the saturation percentage varied from 58 to 191, the electrical conductivity from 0.8 to 28.4 millimhos per centimeter, the exchangeable-sodium percentage from 2.2 to 46.0, the soil pH from 8.1 to 8.9, the content of gypsum from 0 to 21.9 tons per acre-foot, the gypsum requirement from 0 to 23.8 tons per acre-foot, and the hydraulic conductivity from less than 0.005 to 6.24 inches of water per hour. Higher gypsum contents were found in the deep subsoil layers of two soils (profiles 1 and 4). Amounts of gypsum varying from 9.9 to 20.3 tons per acre-foot of depth, are required for the reclamation of the surface layers of these two profiles. In general, the hydraulic- conductivity values show that the soil-surface layers are more permeable than the subsoil layers. 8. The procedure and methods used in this paper were found to be accurate, simple, rapid, and practical. They are recommended for the coordination of data related to the classification and reclamation of soils affected by salinity problems in the different countries of the world.

scholarly journals The impact of Saharan dust and black carbon on albedo and long-term glacier mass balance

2015 ◽  
Vol 9 (1) ◽  
pp. 1133-1175 ◽  
Author(s):  
J. Gabbi ◽  
M. Huss ◽  
A. Bauder ◽  
F. Cao ◽  
M. Schwikowski
Keyword(s):  
Mass Balance ◽  
Black Carbon ◽  
Mineral Dust ◽  
Ice Cores ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
The Impact

Abstract. Light-absorbing impurities in snow and ice control glacier melt as shortwave radiation represents the main component of the surface energy balance. Here, we investigate the long-term effect of snow impurities, i.e. Saharan dust and black carbon (BC), on albedo and glacier mass balance. The analysis was performed over the period 1914–2014 for two sites on Claridenfirn, Swiss Alps, where an outstanding 100 year record of seasonal mass balance measurements is available. Information on atmospheric deposition of mineral dust and BC over the last century was retrieved from two firn/ice cores of high-alpine sites. A combined mass balance and snow/firn layer model was employed to assess the dust/BC-albedo feedback. Compared to pure snow conditions, the presence of Saharan dust and BC lowered the mean annual albedo by 0.04–0.06 and increased melt by 15–19% on average depending on the location on the glacier. BC clearly dominated absorption which is about three times higher than that of mineral dust. The upper site has experienced mainly positive mass balances and impurity layers were continuously buried whereas at the lower site, surface albedo was more strongly influenced by re-exposure of dust-enriched layers due to frequent years with negative mass balances.

The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

1988 ◽  
Vol 10 ◽  
pp. 183-187 ◽  
Author(s):  
D. Wagenbach ◽  
K.O. Münnich ◽  
U. Schotterer ◽  
H. Oeschger
Keyword(s):  
Chemical Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Summer Precipitation ◽  
Snow Accumulation ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Water Conductivity ◽  
Air Masses ◽  
Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust.Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements:(1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic.(2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

scholarly journals The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

1988 ◽  
Vol 10 ◽  
pp. 183-187 ◽  
Author(s):  
D. Wagenbach ◽  
K.O. Münnich ◽  
U. Schotterer ◽  
H. Oeschger
Keyword(s):  
Chemical Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Summer Precipitation ◽  
Snow Accumulation ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Water Conductivity ◽  
Air Masses ◽  
Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust. Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements: (1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic. (2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

scholarly journals The transport history of two Saharan dust events archived in an Alpine ice core

2006 ◽  
Vol 6 (3) ◽  
pp. 667-688 ◽  
Author(s):  
H. Sodemann ◽  
A. S. Palmer ◽  
C. Schwierz ◽  
M. Schwikowski ◽  
H. Wernli
Keyword(s):  
Trajectory Analysis ◽  
Ice Core ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Second Phase ◽  
Transport Pathway ◽  
Dust Sources ◽  
The Alps ◽  
The Mediterranean ◽  
Dust Events

Abstract. Mineral dust from the Saharan desert can be transported across the Mediterranean towards the Alpine region several times a year. When coinciding with snowfall, the dust can be deposited on Alpine glaciers and then appears as yellow or red layers in ice cores. Two such significant dust events were identified in an ice core drilled at the high-accumulation site Piz Zupó in the Swiss Alps (46°22' N, 9°55' E, 3850 m a.s.l.). From stable oxygen isotopes and major ion concentrations, the events were approximately dated as October and March 2000. In order to link the dust record in the ice core to the meteorological situation that led to the dust events, a novel methodology based on back-trajectory analysis was developed. It allowed the detailed analysis of the specific meteorologic flow evolution that was associated with Saharan dust transport into the Alps, and the identification of dust sources, atmospheric transport paths, and wet deposition periods for both dust events. Differences in the chemical signature of the two dust events were interpreted with respect to contributions from the dust sources and aerosol scavenging during the transport. For the October event, the trajectory analysis indicated that dust deposition took place during 13–15 October 2000. Mobilisation areas of dust were mainly identified in the Algerian and Libyan deserts. A combination of an upper-level potential vorticity streamer and a midlevel jet across Algeria first brought moist Atlantic air and later mixed air from the tropics and Saharan desert across the Mediterranean towards the Alps. The March event consisted of two different deposition phases which took place during 17–19 and 23–25 March 2000. The first phase was associated with an exceptional transport pathway past Iceland and towards the Alps from northerly directions. The second phase was similar to the October event. A significant peak of methanesulphonic acid associated with the March dust event was most likely caused by incorporation of biogenic aerosol while passing through the marine boundary layer of the western Mediterranean during a local phytoplankton bloom. From this study, we conclude that for a detailed understanding of the chemical signal recorded in dust events at Piz Zupó, it is essential to consider the whole transport sequence of mineral aerosol, consisting of dust mobilisation, transport, and deposition at the glacier.

scholarly journals Transport and deposition of Saharan dust observed from satellite images and ground measurements

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Habib Senghor ◽  
Alex J. Roberts ◽  
Abdou L. Dieng ◽  
Dahirou Wane ◽  
Cheikh Dione ◽  
...  
Keyword(s):  
North Africa ◽  
Monsoon Season ◽  
Surface Wind ◽  
Early Summer ◽  
Saharan Dust ◽  
Cold Pool ◽  
Convective System ◽  
Long Distance ◽  
Dust Transport ◽  
Convective Storms

Haboob occurrence strongly impacts the annual variability of airborne desert dust in North Africa with more dust raised from erodible surfaces in the early summer (monsoon) season when deep convective storms are common but soil moisture and vegetation cover are low. On 27 June 2018, a large dust storm is initiated in North Africa associated with an intensive westward dust transport. Far away from emission sources, dust is transported over the Atlantic for the long distance. Dust plume is emitted by a strong surface wind and becomes a type of haboob when it merges with the southeastward deep convective system in central Mali at 0200 UTC (27 June). We use satellite observations to describe and estimate the dust mass concentration during the event. Approximately 93% of emitted dust is removed from the atmosphere between sources (10°N–25°N; 1°W–8°E) and the African coast (6°N–21°N; 16°W–10°W). The convective cold pool has induced large economic and healthy damages, and death of animals in the northeastern side of Senegal. ERA5 reanalysis have shown that the convective mesoscale impacts strongly the climatological location of the Saharan heat low (SHL).

scholarly journals Deterioration of surface layers of tungsten and steel-containing materials in current collection sliding against molybdenum

2021 ◽  
Vol 64 (2) ◽  
pp. 122-128
Author(s):  
M. I. Aleutdinova ◽  
V. V. Fadin
Keyword(s):  
Electrical Conductivity ◽  
Iron Oxides ◽  
Electrical Contact ◽  
Bearing Steel ◽  
Wear Intensity ◽  
Oxide Content ◽  
Molybdenum Oxides ◽  
Sliding Surface ◽  
Surface Layers ◽  
Current Collection

The possibility of improving the characteristics of a dry sliding electrical contact with a current density higher than 100 A/cm2 by using a molybdenum counterbody is considered. It is shown that tungsten or metallic materials containing bearing steel (1.5 % Cr) in sliding against molybdenum at a speed of 5 m/s under electric current, forms a contact with low electrical conductivity and high wear intensity. This observation served as the basis of this work. Using optical and electron microscopy of sliding surfaces it was found that strong adhesion in the interface was the main reason for rapid surface layers deterioration and high wear intensity. A well-known statement was taken into account that adhesion is due to the low oxide content between the contact surfaces. Visual study of molybdenum sliding surface made it possible to establish formation of a thin transfer layer and absence of traces of oxide formation. The same was observed on sliding surface of tungsten that was caused by high temperature of tungsten and molybdenum oxides formation. A layer of iron oxides was observed on sliding surface of steel containing materials. In addition, traces of a thin tribolayer were find out. An increase in concentration of steel in the primary structure led to a slight increase in iron oxides on the sliding surface, but did not lead to a significant increase in electrical conductivity and wear resistance of the contact. Unsatisfactory characteristics of the contact allowed us to conclude that it is impossible to significantly improve sliding parameters with current collection against molybdenum and inappropriateness of its use as a counterbody for these conditions.

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