摘要:

ABSTRACTThis study reports on an analysis of a Landsat- 5 TM band 6 image from an October night 1988. With radiosonde data and an atmospheric propagation model definite temperatures are determined. Examples are given of how the imagery can be used for analyses of some hydrological phenomena, like fast radiative cooling of lake water surfaces, and coastal upwelling. The satellite derived temperature patterns on clear-cuts are examined, especially with the relation to elevation, aspect and slope.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880296

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTThe hydrologic processes of a perennial snowbank located in an area of continuous permafrost were examined. The major source of water for the snowbank was surface ablation, while the major sinks were outflow and basal ice growth. Subsurface flow from the active layer upslope and summer precipitation were unimportant as an inputs. Each diurnal outflow hydrograph exhibited a distinct plateau following the rising limb. This characteristic has not been observed in other studies of arctic snowmelt and is attributed to the great thickness of snow and the spatial heterogeneity of snow depths at the field site. Lag times between surface energy inputs and outflow did not follow a regular trend over the summer but recession limbs showed a slight steepening, reflecting gradual thinning of the snowbank.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880297

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTLimited data are available on flow dynamics and suspended sediment transport in ephemeral, semiarid drainage systems, particularly in tropical regions. Data for three representative low magnitude flow events were chosen to examine the temporal variability of suspended sediment particle-size and flow dynamics. Data were obtained from a one year monitoring programme in a 0.30 km2ephemeral drainage system in Kenya. Surface sealing of sodium rich units produced a rapid runoff response, with hydrograph rise-times of0.23 mm event-1. Particle-size analysis of suspended sediment indicated that hillslopes were the main source areas for sediment production. Variations in suspended sand, silt and clay concentrations with discharge were complex for three flow events. Regression models determined for individual events were not always significant (P = 0.05). However, if they were significant the coefficient of non-determination (1 - r2) was generally low especially when grain size concentration data for the three storm events were grouped. The high unexplained variation resulted from temporal lumping of all storm data which is an inherent problem of rating curves. Values predicted from rating curves are not absolute, and must be used cautiously when attempting to predict sediment, nutrient and contaminant loads from catchments.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880298

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTIn a pilot study to identify the annual layers in superimposed ice a 6.8 m long ice core has been investigated. The ice core was recovered from the summit of Storöyjökulen, a small ice cap in northeastern Svalbard that is entirely nourished by superimposed ice.Large variations in ice texture (crystal size and shape), ice structure (bubbliness), microparticle content, and solid electrical conductivity have been found and interpreted as representing seasonal cycles as they normally vary in phase. The combination of many ice core parameters has also allowed the clarification of many ambigious features. Thick layers of coarse, sometimes elongated ice crystals which have a high microparticle content as well as high solid electrical conductivity, have been used as indicators of late summer conditions. Dating the ice core has thus been accomplished by equating the upper surfaces of these coarse-grained layers with summer surfaces. Using these summer surfaces the net balance at the summit of Storöyjökulen has been calculated and found to be 27 cm of ice between 1954 and 1979.A good correlation has been found between the net balance at the summit of Storöyjökulen and the mean temperature at Hopen in southeastern Svalbard, if the temperatures are calculated per mass balance year. This correlation also indicates that there are no missing years in the record, that is, no years with negative mass balance at the summit of the ice cap.Oxygen isotopes were also measured in the core, but were of no use for dating purposes. However, when averageδ18O values were calculated for the different mass balance years (identified by the methods mentioned above) and plotted against the net balance values, two parallel curves resulted. This, of course, gives further support for the dating method described above.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880299

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTThe upper slopes of the Asgard and Olympus ranges, of the Transantarctic Mountains, have been assessed for their rock mass strength. A finite-element model of two peaks has shown that under gravitational loading they have a tendency to spread laterally as a result of internal stresses. Stress release joints and slab failures are a consequence of this loading. The characteristic slope forms are cliffs in strength equilibrium surmounting Richter denudationslopes. It is argued that the ubiquity of such forms, and their antiquity, make an hypothesis of high-level glacial overriding unverifiable.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880300

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTDetailed morphological analysis of the boulder fields on the Mt. Fulufjället plateau has revealed three morphologically and genetically different boulder field types; 1/ boulder depressions related to upfreezing in till, 2/ boulder blankets, i.e. glacially transported boulder masses, and 3/ frost-shattered debris in situ. Two distinctly different landscape types are related to the boulder fields of type 1 and 2. At the border between landscape types it can be shown that the boulder depressions and the associated patterned ground were in existence before the last overriding ice sheet, and consequetly are of a pre-Late Weichselian age. The material found in the glacially transported boulder blankets is shown mainly to be derived from boulder depressions. Drawn-out“tails”from boulder depressions are interpreted to be related to lateral shear zones between cold- and warm based zones of the ice sheet. No large-scale periglacial forms appear to have developed on the plateau during the Holocene. An area of more than 60 km2of an interstadial periglacial landscape has survived virtually unchanged despite complete ice cover during the late Weichselian.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880301

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTThe paper is based on observations of relict periglacial structures in a 40 km long pipeline section which was dug through a coastal plain of southwestern Sweden, lee-wedge formation and wedge characteristics in a broad range of matrices (glaciofluvium, glaciomarine sediments, till and eolian deposits) are analyzed. The distribution of ice wedges according to the upheaval of the area in Late Weichselian is considered and the chronology of polygon formation discussed by means of shore-line spectra and radiocarbon dating. The past arctic environment (the Dryas cold phases) is elucidated by comparison with present periglacial processes in areas of West Spitsbergen with an analogous geographical character (isostatically raised coastal plain with loose deposits).

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880302

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTWidespread eolian sand deposits occur in the central Kobuk Valley in northwestern Alaska. Major dune development in this valley was synchronous with the onset of the last glacial advance about 24 000 years B.R and reflects an abundant supply of sandy sediments derived from glacial erosion and fluvial redeposition.The morphology of the dune fields is described by airphoto interpretation supplemented by field observations. The largest active dune field (the Great Kobuk Sand Dunes) is characterized by large transverse and barchanoid dune ridges, and flat interdune areas, representing a dry eolian environment with abundant sand supply. However, in the eastern part of the study area complex, elongated, parabolic dunes as well as eolian sand sheets represent a moist eolian phase in a mainly vegetated area. These dunes are largely stabilized and very uniformly orientated WNW-ESE. Dune forms indicate that both present-day and former wind directions are parallel to the valley axis. Due to the opposite bimodal wind regime parabolic dune heads have developed in two opposite directions, giving rise to the rare phenomenon of hairpin' dunes converging at both ends of the blowouts. These forms are called‘canoe-shaped blowout dunes’. It is concluded that specific dune forms characteristic for periglacial and/or permafrost conditions are unknown.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880303

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTIn this paper, a comparison between two small valley glaciers in northern Sweden, Rabots glaciär and Storglaciären is presented. Measurements on Rabots glaciär over the last decade give the opportunity to validate the representativity of the long mass balance record from Storglaciären for climatic studies. An excellent agreement in the trend of the net mass balance between the glaciers has been found. A comparison between the net annual velocities of both glaciers revealed similar patterns.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880304

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

ABSTRACTMass balance measurements for the balance years 1985/86, 1986/87 and 1987/88 and calculations of the volume changes since the last maximum around 1915 have been carried out for Sydöstra Kaskasatjäkkoglaciären and Tarfalaglaciären in the Kebnekaise massif, Northern Sweden. A measure of the sensibility to climatic changes is given by the relationship between the mass balance volumes and the volumes of the glaciers. A comparison with Storglaciären and Rabots glaciär shows that Sydöstra Kaskasatjåkkoglaciären and Tarfalaglaciären are much more sensitive to climatic changes.

ISSN:0435-3676    

DOI:10.1080/04353676.1990.11880305

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor