bluuebunny/crossref_metadata_2025 huggingface dataset:
Mental Health Status of a Latin American Community in New South Wales
Authors: McDonald Robert , Vechi Carmen , Bowman Jenny , Sanson-Fisher Robert
Published: November 2007

Objective: To determine the levels and predictors of psychological distress within a Latin American community in the Hunter region of New South Wales, Australia.

Method: Participants (n=184) were interviewed in their homes by a bilingual interviewer using a specially prepared questionnaire and the General Health Questionnaire (GHQ-12).

Results: Of the 13 independent variables examined, two demographic and two immigrant-related variables were significantly associated with an above-threshold score: marital status, employment status, perceived discrimination, and dissatisfaction with life in Australia.

Conclusions: Compared to results from other community surveys, the levels of psychological distress within this Latin American community appear to be relatively high.
Pathological Laughing and Crying
Authors: Dark Frances L. , McGrath John J. , Ron Maria A.
Published: November 2007

Objective: To review the clinical features, neurobiological correlates and treatment of pathological laughing and crying. Method: Selective literature review.

Results: Attacks of involuntary, irresistible laughing or crying have long been recognised as sequelae of brain damage. There is controversy about the clinical features of these attacks, the stimuli that provoke them and their relation to affective disorder. The pathophysiology of pathological laughing and crying is still unclear. It can occur in the presence of focal as well as diffuse brain disease. Treatment with antidepressant medications has been found to be of benefit in patients with cerebrovascular disease and multiple sclerosis. Conclusions: Clinicians should remain vigilant for these symptoms, and offer effective treatments, such as antidepressants, where indicated. Further research is needed to delineate the underlying neurobiological correlates of pathological laughing and crying. The efficacy of both pharmacological and non-pharmacological interventions requires critical evaluation.
Psychological Morbidity in Obstetric-Gynaecology Patients: Testing the Need for Expanded Psychiatry Services in Obstetric-Gynaecology Facilities
Authors: Phillips Nicole , Dennerstein Lorraine , Farish Stephen
Published: November 2007

Objective: The present study set out to determine general levels of distress, anxiety and depression in an obstetric-gynaecology inpatient population and to ascertain levels of patient satisfaction with services.

Method: 200 English-speaking consecutive admissions to the hospital filled out a package of questionnaires consisting of a demographic data form, the 30-item General Health Questionnaire, the Speilberger State-Trait Anxiety Inventory, the Inventory to Diagnose Depression and a Patient Satisfaction with Services Questionnaire. 134 packages were fully completed.

Results: The most significant findings were: first, that high levels of anxiety prevailed, with approximately 1/3 of patients at or above the 75th percentile for anxiety levels; and second, that those patients born in non-English speaking countries were significantly more dissatisfied with their care.

Conclusions: The results of this study suggest that there is a need for increased awareness of and further research into the psychological needs of obstetric-gynaecology patients.
Attitudes of the Vietnamese Community towards Mental Illness
Authors: Lien On
Published: November 2007

There are approximately 155,000 Vietnamese born people in Australia, with 46,000 in Victoria. The majority came to Australia as refugees. Many were subjected to the reality or threat of war, persecution, imprisonment, discrimination, economic deprivation, violence, the loss of family or other major stressors. These stressors have included the hazards of the escape, lengthy stays in refugee camps and, on arrival in Australia, lack of familiarity with English and with the culture. The Vietnamese Community in Australia was expected to have a high prevalence of mental illness, especially when newly arrived from refugee camps. In a study published in 1986 as “The Price of Freedom” [1] 32% of the young Vietnamese adult group was found to suffer from psychiatric disorder. At follow-up two years later, the prevalence of psychiatric disorder, without any major intervention, had dropped to 5–6%, a prevalence lower than that in the Australian-born community. In addition, the Vietnamese community's use of mental health services (inpatient and community-based) is lower than that of any other ethnic group.
Euthanasia and the Death of Freud
Authors: Ellard John
Published: November 2007

The practice of medicine confronts the practitioner with many sad, urgent and cruel happenings. No case is quite like another, and there are decisions to be made when all the Possible answers are tragedies. Life can ecome such a burden that the struggle to maintain it raises the final question.
Clozapine: A Case Vignette
Authors: Nayman Ilana
Published: November 2007

This paper describes successful clozapine treatment in a young woman with a five year history of treatment-resistant schizophrenia. After various treatment-resistant strategies had been given, clozapine was commenced. Symptom resolution within 4 months and sustained high level of functioning within 7 months was achieved. The role of clozapine in general psychiatric practice is evident. Clozapine should be considered earlier in the illness course than was formerly the case.
Development of radar glacier zones on the King George Island ice cap, Antarctica, during austral summer 1996/97 as observed in ERS-2 SAR data
Authors: Braun Matthias , Rau Frank , Saurer Helmut , Gobmann Hermann
Published: November 2007

Based on a time series of European remote-sensing satellite (ERS-2) synthetic-aperture radar (SAR) images from 1996/97, ablation on the King George Island (Antarctica) ice cap is documented. Snowmelt patterns were monitored by mapping the dynamic evolution of radar glacier zones and their boundaries. On the ice cap, all major radar glacier zones except the dry-snow radar zone were identified during the observed period While winter was characterized by a frozen-percolation radar zone, the ablation season was characterized by wet-snow and bare-ice radar zones. A striking bright backscatter signature indicated the presence of a highly reflective zone in the lower parts of the wet-snow zone. It was attributed to a phase 2 melt (P2) radar zone, which is characterized by a metamorphosed and roughened surface of a melting snow cover. Due to the absence of simultaneously acquired ground-truth information, concurrent meteorological data proved to be essential for interpreting the SAR images. Although the maximum elevation of the ice cap does not exceed 680 ma.s.L, ablation patterns obviously reflect altitudinal control. Melt onset up to 530 m a.s.l. was initiated by an advection event at the end of October 1996. A wet snowpack on the entire ice cap corresponds with a prolonged period of high temperatures in January 1997. However, the highest parts of the ice cap were affected by occasional melt-freeze cycles. The transient snowline at the end of February was determined as being at 250 m a i l. This late-summer snowline was regarded as an approximation of the equilibrium-line altitude for the 1996/97 ablation season.
Wind propagation to snow observed in laboratory
Authors: Sokratov S. A. , Sato A.
Published: November 2007

Non-uniformity of a temperature field in a 30 cm deep artificial snow cover in a wind tunnel was produced by keeping a selected cross-section, perpendicular to the wind direction, at a temperature different to that in the cold room. Quasi-steady-state temperature distributions in the snow around this cross-section were observed with and without wind, and were significantly different. The difference was attributed to the influence of an air flux inside the snow cover. The mechanism of this influence is discussed. Several temperature conditions and wind speeds over the snow surface were studied. It was concluded that the wind produced the air flux in the pore space of snow, and the air-flux velocity increases with wind speed. The calculated values of the horizontal air-flux velocity in the pore space of snow were of the order of l0–2 m s"1 and decreased with depth.
Verification of geophysical models in Alpine permafrost using borehole information
Authors: Vonder Mühll Daniel S. , Hauck Christian , Lehmann Frank
Published: November 2007

At two permafrost sites in the Swiss Alps a range of geophysical methods were applied to model the structure of the subsurface. At both sites, borehole information was used to verify the quality of the model results. On the Murtèl-Corvatsch rock glacier (2700 m a.s.L; upper Engadine) a 58 m deep core drilling was performed in 1987. D. c resistivity measurements, refraction seismics, ground-penetrating radar (GPR) and gravimetric surveys allowed the shape of the permafrost table beneath the marked surface microtopography to be determined and the lateral extent of a deeper shear horizon to be established The validity of each method was verified by the borehole information (cores, density log and temperature). A coherent model of the rock-glacier structure was developed. At the Schilthorn (2970 m a.s.L; Bernese Oberland), it was not clear whether permafrost is in fact present. Various geophysical surveys (d.c. resistivity tomography, refraction seismics, GPR and EM-31) gave results that were not typical of permafrost environments. A 14 m percussion drilling revealed warm permafrost and a very low ice content. These geotechnical and geothermal data allowed reinterpretation of the geophysical results, improving modelling of ground conditions. The paper demonstrates that in the difficult terrain of Alpine permafrost, boreholes may be critical in calibration and verification of the results of geophysical methods. The most useful combinations of geophysical techniques proved to be (a) seismics with d.c. resistivity, and (b) gravimetry with GPR.
Mass balance of Xiao Dongkemadi glacier on the central Tibetan Plateau from 1989 to 1995
Authors: Fujita Koji , Ageta Yutaka , Jianchen Pu , Tandong Yao
Published: November 2007

Data on the mass balance of Xiao Dongkemadi glacier in the Tanggula mountains, central Tibetan Plateau, were obtained over 5 5 years from 1989 to 1995. These are the first continuous mass-balance data for a continental-type glacier on the Tibetan Plateau, where the glacier accumulates during the summer monsoon (summer-accumulation-type glacier). Mass-balance vs altitude profiles were steeper in the negative than in the positive mass-balance years. This is considered to have resulted from the effect of summer accumulation. The annual mass balance is compared with air temperature, precipitation, and black-body temperature in the area including the glacier, which is calculated from infrared radiation observations by theJapanese Geostationary Meteorological Satellite. It was found that the interannual variation in the glacier mass balance was not closely related to maximum monthly mean air temperature, while it did have a relatively good correlation with maximum monthly mean black-body temperature.
Glacier monitoring within the Global Climate Observing System
Authors: Haeberli Wilfried , Cihlar Josef , Barry Roger G.
Published: November 2007

The fluctuation of mountain glaciers is recognized as a high-confidence indicator of air-temperature trends and as a valuable element of a strategy for early detection of possible Man-induced climate changes. The Terrestrial Observation Panel for Climate therefore recommended that glacier mass and area be monitored as part of the Global Climate Observing System (GCOS) established in 1992 by the World Meteorological Organization, the Intergovernmental Oceanographic Commission, the United Nations Environment Programme and the International Council of Scientific Unions. A tiered Global Hierarchical Observing Strategy was developed to be used for all GCOS terrestrial variables. According to this system of tiers, the regional to global representativeness in space and time of the records relating to glacier mass and area should be assessed by more numerous observations of glacier length changes as well as by compilation of regional glacier inventories repeated at time intervals of a few decades, the typical dynamic response time of smaller mountain glaciers.

During the 1970s, Fritz Müller directed the Permanent Service on the Fluctuations of Glaciers and the Temporary Technical Secretariat for the World Glacier Inventory. These two bodies were combined in 1986 to form the World Glacier Monitoring Service, which is now responsible for internationally coordinated glacier monitoring, working in close collaboration with the World Data Center for Glaciology, Boulder.
Towards a palaeoclimatic model of rock-glacier formation in the Swiss Alps
Authors: Frauenfelder Regula , Kääb Andreas
Published: November 2007

Climate and its long-term variability govern ground thermal conditions, and for this reason represent one of the most important impacts on creeping mountain permafrost. The decoding and better understanding of the present-day morphology and distribution of rock glaciers opens up a variety of insights into past and present environmental, especially climatic, conditions on a local to regional scale. The present study was carried out in the Swiss Alps using two different approaches: (1) kinematic analysis of specific active rock glaciers, and (2) description of the altitudinal distribution of relict rock glaciers. Two theoretical shape concepts of active rock-glacier morphology were derived’ a"monomorphic" type, representing presumably undisturbed, continuous development over several millennia and a ˚polymorphic" type, reflecting a system of (possibly climatically affected) individual creep streams several centuries old. The topoclimatic-based inventory analysis indicated an average temperature increase at relict rock-glacier fronts of approximately +2°C since the time of their decay, which is a sign of rock-glacier ages reaching back to the Alpine Late Glacial. The temperature difference of some tenths of a degree Celsius found for active/inactive rock glaciers is typical for the bandwidth of Holocene climate variations. These results confirm the importance of Alpine rock glaciers as highly sensitive indicators of past temperature evolution.
First results and interpretation of energy-flux measurements over Alpine permafrost
Authors: Mittaz Catherine , Hoelzle Martin , Haeberli Wilfried
Published: November 2007

The interaction of energy-exchange processes between the atmosphere and the Earth surface determines the surface temperature regime. It is of fundamental importance to the question whether frozen ground exists at a given site and how rapidly it may decay in response to a climatic perturbation. To further our understanding of these processes, measurements concerning near-surface energy-exchange processes were initiated in January 1997 on creeping permafrost at a high mountain site, Murtèl-Corvatsch, upper Engadin, Swiss Alps. Data on all important energy-balance fluxes were collected. In this paper, we present ground-temperature and energy-balance measurements from Murtèl-Corvatsch for a 2 year period, 1997–99. We will examine the relative importance of the energy-balance components and discuss special problems relating to the coarse surface layer. The results indicate a non-zero energy budget, with a positive deviation of up to 78 W m 4 in winter and a negative deviation of up to –130 W nT2 in summer. We propose that this overall imbalance of the energy-exchange fluxes, as well as the significant difference between mean annual surface and ground temperatures/can be explained by unmeasured advective energy fluxes that occur within the layer of large boulder blocks at the top of the permafrost.
Spatial gradients in snow layering and 10 m temperatures at two EPICA-Dronning Maud Land (Antarctica) pre-site-survey drill sites
Authors: Holmlund P. , Gjerde K. , Gundestrup N. , Hansson M. , Isaksson E. , Karlöf L. , Nman M. , Pettersson R. , Pinglot F. , Reijmer C. H. , Stenberg M. , Thomassen M. , van de Wal R. , van der Veen C. , Wilhelms F. , winther J.-G.
Published: November 2007

During the 1997/98 field season, Sweden, Norway and The Netherlands performed a pre-site survey for EPICA in Dronning Maud Land, Antarctica. This paper summarizes the results and pays special attention to the high spatial gradients found in snow layering and temperatures. The sites were "Camp Victoria" (CV) on Amundsenisen (76° S, 8° W; 2400 m a.s.l.), approximately 550 km from the coast, and "Camp Maudheimvidda" (CM) on Maudheimvidda (74° S 13° W; 362 m a.s.L), some 140 km from the coast.

The drilling programme included both medium-long firn/ice cores and shallow firn cores. These were analysed by means of δ18O, DEP, ECM,β activity, density, and ion content. The combined results suggests a mean annual accumulation rate of 60 mm. we. for CV and 220 mm. we. for CM.

Variability measurements of spatial snow layering were performed at two scales; over tens of kilometres by radar and over a few metres by pits and high-resolution radar soundings. Results, as measured by relative standard deviation, were typically 10% on the polar plateau and as high as 50% near the coast.

The 10 m temperature measurements were –38.5°C (std dev. = 0.5°) for CV and –17.6°C (std dev.=0.15°) for CM.

Snow chemistry was sampled at each medium-long-core drill site. Comparison of δ18O profiles from snow pits and the uppermost part of the CV medium-long core showed large variations. Mean δ18O valuesover 2 m profiles varied between 41.6%, and 39.7%o within a horizontal distance of 50 m.
A conceptual model for pancake-ice formation in a wave field
Authors: Shen Hayley H. , Ackley Stephen F. , Hopkins Mark A.
Published: November 2007

It is well known that waves jostle frazil-ice crystals together, providing opportunities for them to compact into floes. The shape of these consolidated floes is nearly circular, hence the name: pancakes. From field and laboratory observations, the size of these pancakes seems to depend on the wavelength. Further aggregation of these individual pancakes produces the seasonal ice cover. Pancake-ice covers prevail in the marginal ice zone of the Southern Ocean and along the edges of many polar and subpolar seas. This theoretical paper describes conceptually the formation process of a pancake-ice cover in a wave field. The mechanisms that affect the evolution of the entire ice cover are discussed. Governing equations for the time-rate change of the floe diameter, its thickness and the thickness of the ice-cover are derived based on these mechanisms. Two criteria are proposed to determine the maximum floe size under a given wave condition, one based on bending and the other on stretching. Field and laboratory observations to date are discussed in view of this theory.
Effects of regional fast-ice and iceberg distributions on the behaviour of the Mertz Glacier polynya, East Antarctica
Authors: Massom R. A. , Hill K. L. , Lytle V. I. , Worby A. P. , Paget M.J. , Allison I.
Published: November 2007

An observational account of research carried out in July-August 1999 shows that grounded iceberg and related fast-ice distributions, and periodic "break-outs" of fast ice (in winter as well as at other times), have an important impact on the size and behaviour of the Mertz Glacier polynya, East Antarctica, and a smaller polynya to the east. Analysis of satellite and in situ data shows that a semi-constant "stream" of thick broken-out fast ice and other large floes from the east extends westwards from north of the glacier terminus to form a compact barrier to the net west-northwesterly export of ice formed in the polynya. An annual fast-ice promontory to the west further narrows the outlet path. As a result of this and high ice-production rates, the polynya periodically "back-fills", significantly reducing the open-water area present. Intervening "flush-outs" by synoptic storm events clear the polynya region to some extent before it back-fills again. This cycle continued from mid-March until early October in 1999, when a significant change in the regional ice drift occurred. A preliminary comparison with data from 1998 indicates that the timing and magnitude of the processes may vary interannually. Similar morphological features were also observed in 1963 (on a declassified photoreconnaissance satellite image).
Vertical zonation and community transition of sea-ice diatoms in fast ice and platelet layer, Weddell Sea, Antarctica
Authors: Günther Sven , Dieckmann Gerhard S.
Published: November 2007

Changes in the taxonomic composition of diatoms in fast ice as well as in the underlying platelet layer were followed from June to December 1995 in Atka Bay Antarctica. Four communities were clearly distinguished: (1) an interior community dominated by flagellates in spring; (2) a bottom community dominated by a small form ofFragilariopsis cylindrus;(3) a platelet-ice layer dominated byAmphiprora KufferathiiandThalassionemasp. growing attached to the ice platelets; and (4) an interstitial community dominated byChaetoceros neglectusgrowing in the water between the platelets. Species composition distribution and succession in these communities were related to changes in silicate concentration, pore space and ice-formation processes and the ability of some cells to grow attached to ice platelets. The presence of the platelet-layer communities may have implications for paleoglaciology
Properties and structure of the seasonal snow cover in the continental regions of China
Authors: Wenshou Wei , Dahe Qin , Mingzhe Liu
Published: November 2007

The continental regions of China are extensively covered by snow during winter. In this paper, the seasonal snow cover in the Tien Shan and Altay mountains is observed and analyzed, based on the characteristics of the dry-cold snow cover accumulating under the continental climatic conditions in northwest China. Compared with the humid-warm snow cover, the dry-cold snow cover is characterized mainly by small density, low water content, large temperature gradient, thick depth hoar, etc., and its metamorphism is dominated by the thermal exchange and the pressure of the overlying snow layers. According to the observed data, the solar radiation flux on the snow surface is dominated by a negative balance in the arid areas in China during the snow season; the albedo on the new-fallen-snow surface is up to 96%, and the transmission depth of shortwave radiation in dry-cold snow cover is 28 cm. During the snowmelt season in spring, the thickness of the depth hoar can occupy 80% of the whole snow cover.
Time–space linear regression analysis of the snow cover in a pre-Alpine semi-forested catchment
Authors: Stähli Manfred , Papritz Andreas , Waldner Peter , Forster Felix
Published: November 2007

Sub-grid variability of the snow cover is an important issue with regard to catchment runoff or mesoscale meteorological modeling. Here, an evaluation is presented of spatial snow measurements conducted on 5 days in winter 1998/99 and 2 days in winter 1999/2000 in a 0.7 km2Swiss pre-Alpine catchment. Snow-depth data were analyzed with two different linear regression models, one including altitude, terrain slope, terrain aspect and canopy density, and one using altitude and simple land-use indicators. For the single measurement date/the first model was somewhat superior to the indicator model. The error term of the regression models showed only weak spatial dependence. Finally, a time-space linear regression model describing both the temporal development and the spatial distribution of the snow cover was fitted with the measurements of the first winter and tested with measurements of the second winter. The validation showed a satisfactory match between measurements and models in late December, but a slight overestimation of the measurements by the models in early April. In view of the models’ability to reproduce the snow-depth patterns satisfactorily at this rather detailed scale, it was concluded that such regression models might be a suitable tool to treat sub-grid variability of snow depth in larger-scale models.
Past 220 year bipolar volcanic signals: remarks on common features of their source volcanic eruptions
Authors: Kohno Mika , Fujii Yoshiyuki
Published: November 2007

During the past 220 years, prominent signals of non-sea salt sulfate ion (nssSO42–) concentration exceeding the background level, including both marine biogenic and anthropogenic SO42–, were found in shallow ice cores from site H15 in East Antarctica and Site-J in southern Greenland. They were mostly correlated with past explosive volcanic eruptions. on the basis of this result and published results of shallow ice cores and snow pits at various locations on the Antarctic and Greenland ice sheets, eight common signals were found, of which six were assigned to the following explosive eruptions: El Chichόn, Mexico, in 1982; Agung, Indonesia, in 1963; Santa Maria, Guatemala, in 1902; Krakatau, Indonesia, in 1883; Cosiguina, Nicaragua, in 1835; an unknown volcano between 1831 and 1834; Tambora, Indonesia, in 1815; and an unknown volcano in 1809. Volcanic eruptions which have a potential to imprint their signals in both the Antarctic and Greenland ice sheets were characterized by (1) location in low latitudes between 20˚N and 10˚ S, and (2) eruption column height ≥25 km, corresponding to a volcanic explosivity index (VEI) ≥5.
High net accumulation rates at Campo deHielo Patagόnico Sur, South America, revealed by analysis of a 45.97 m long ice core
Authors: Shiraiwa Takayuki , Kohshima Shiro , Uemura Ryu , Yoshida Naohiro , Matoba Sumito , Uetake Jun , Godoi Maria Angelica
Published: November 2007

A 45.97 m long ice core was recovered in the accumulation area of Glaciar Tyndall (50˚59’05’’ S, 73˚31’12’’W; 1756ma.s.l.), Campo de Hielo Patagόnico Sur (southern Patagonia icefield), during December 1999. the firn core was subjected to visual stratigraphic observation and bulk density measurements in the field, and later to analyses of water isotopes (δ18O, δD), major dissolved ions and snow algal biomass. the drillhole remained dry down to about 43 m depth, where a water-soaked layer appeared. Seasonal cycles were found for δ18O, δD and the D-excess, although the amplitudes of the cycles decreased with depth. Major dissolved ions (Na+, K+, Mg2+, Ca2+, Cl–, SO42–) and algal biomass exhibit rapid decreases in the upper 3 m, probably due to meltwater elution. Annual increments defined by the δ18O and D-excess peaks suggest that the minimum net accumulation rates at this location were 17.8ma–1 in 1997/98–1998/99 and 411.0 ma–1 in 1998/99–1999/2000. These are much higher values than those previously obtained from past ice-core studies in Patagonia, but are of the same order of magnitude as those predicted from various observations in ablation areas of Patagonian glaciers.
Electrical measurements on the 2503 m Dome F Antarctic ice core
Authors: Fujita Shuji , Azuma Nobuhiko , Motoyama Hideaki , Kameda Takao , Narita Hideki , Fujii Yoshiyuki , Watanabe Okitsugu
Published: November 2007

The 320 kyr climatic record from the 2503 m Dome Fuji (Antarctica) ice core was analyzed using two electrical methods: AC-ECM and ECM (electrical conductivity measurements). AC-ECM is a method to detect the complex admittance between electrodes dragged on the ice surface with mm-scale resolution and uses 1V and 1 MHz. the ratio of the real to imaginary part of the admittance is the AC loss factor, which responds linearly to the amount of sulfuric acid and hydrogen ions. Both the AC loss factor and the ECM current respond to acid, but the ECM signal tends to saturate at high acidities. Dome Fuji ice was measured to be highly acidic, with background values of 2–7 μM, and had 4500 major peaks with acidities of up to 90 μM. This ice-core evidence and earlier snow-chemistry survey around the dome region indicates that Dome F may have a better connection to the stratosphere than have sites at lower altitude, which allows more stratospheric aerosol and gases to reach the snow surface. Acidity tends to be high in interglacial periods, but correlation between acidity and δ18O is not straightforward. Electrical signals decreased and smoothed out with increasing depth; the diffusion coefficients deduced from this smoothing were 10–102 times greater than in solid ice. the ice core exhibited electromechanical effects and expelling effects from sulfate peaks.
Cold firn in the Mont Blanc and Monte Rosa areas, European Alps: spatial distribution and statistical models
Authors: Suter Stephan , Hoelzle Martin
Published: November 2007

Near-surface firn temperatures were measured in 22 steam-drilled boreholes in the summit region of Mont Blanc (France and Italy) at 3800 –4800ma.s.l. in June 1998 and in 31 boreholes in the Monte Rosa area (Italy and Switzerland) at 3900– 4500ma.s.l. in May–July 1999. Borehole temperatures were logged to 22 m depth. the temperatures at 18 m depth ranged between temperate conditions and approximately –15˚C. In a small altitude band, the observed distribution pattern suggests a strong influence of shortwave radiation and turbulent heat exchange (being generally more effective at wind-exposed sites). These two energy fluxes mainly determine the melt-energy input into the snow and firn during summer and, thereby, the measured near-surface temperatures. A statistical analysis of the measured firn temperatures revealed altitude-dependent firn temperature gradients of –1.48 and of –2.36˚C (100m)–1 for the Mont Blanc and Monte Rosa areas, respectively. the high lapse rates, as compared to the air-temperature lapse rate, are the result of englacial latent-heat contribution. the parameters elevation, potential direct solar radiation, slope and accumulation explain 480% of the variation of the mean annual firn temperatures. Aspect-dependent lower boundaries for the cold-firn occurrence in the two areas ranged between 3500 and 4100 ma.s.l.
Retrieval of snow reflectance from Landsat data in rugged terrain
Authors: Xin Li , Koike Toshio , Guodong Cheng
Published: November 2007

We developed a model to calculate the spectral reflectance of snow by normalizing the topographic effect and correcting the atmospheric effect simultaneously. This model considers the shadowing effect of the surrounding terrain on both direct and diffuse irradiance by using the obstruction coefficient in sun-ray direction and introducing the isotropic view factor. In addition, a new method to calculate the surrounding-reflected irradiance by introducing the shape factor which can account for the radiation reflected from the surrounding pixels was developed. The model was tested in the upper stream of the Heihe river basin, Qilian mountains, China, using a subscene of a Landsat Enhanced Thematic Mapper Plus (ETM+) image acquired on 20 April 2000. The result showed that the model could eliminate most of the shadowing effect of rugged terrain and could estimate snow reflectance correctly. The problem of data saturation when retrieving snow reflectance is also discussed.
RADARSAT interferometry for Antarctic grounding-zone mapping
Authors: Gray L. , Short N. , Bindschadler R. , Joughin I. , Padman L. , Vornberger P. , Khananian A.
Published: November 2007

Satellite radar interferometry (SRI) is used to provide new information on grounding zones in areas of the eastern Ross Ice Shelf and the Filchner Ice Shelf, Antarctica. At the times of the RADARSAT SRI passes, separated by 24 days, a tidal model predicts a change in vertical displacement of the freely floating ice of >1 m in both areas. The change in vertical position occurs over a 5–10 km flexure zone adjacent to the grounding line and would lead to a relatively high interferometric phase fringe rate. This was observed in some areas, and suitable imagery has been used to map the grounding-zone position to an estimated accuracy of 1–2 km. Results for the ice-plain area upstream of the Crary Ice Rise are consistent with the tidal model and improve the previous grounding-line estimates based on field surveys and Système Probatoire pour l’Observation de la Terre (SPOT) data. The results support the suggestion of increased ice grounding in this area, and show that a sub-ice-shelf water channel around the southern end of the Crary Ice Rise is unlikely. Results for the Filchner Ice Shelf also show that existing maps of the grounding zone can be refined. In particular, we identify a large ice rise close to the mouth of the Bailey Ice Stream.
Usage of high-resolution Landsat 7 band 8 for single-band snow-cover classification
Authors: W.Vogel Stefan
Published: November 2007

With the launch of Landsat 7 a new band was added to the Landsat Enhanced Thematic Mapper Plus (ETM+). The new panchromatic band 8 covers wavelengths of 0.52–0.92μm and extends over band 2 (0.525–0.605 μm), band 3 (0.630–0.690 μm) and band 4 (0.750–0.900 μm). Its high resolution, with a pixel length of 15 m, is of interest for high-spatial-resolution analysis. This project focused on using Landsat 7 band 8 as a precise tool to obtain remotely the size and shape of permanent snowpatches in the mountainous area west of Abisko, Sweden. In the supervised classification employed, shadowed and non-shadowed areas were classified separately. Supervision of the classification was based on ground-truthing consisting of photographic mapping of the snow cover in the study area. The results from this single-band classification were compared to the results from the normalized- difference snow index (NDSI) and false-color images using bands 2, 4 and 5. This comparison showed similar estimates of the total amount of snow-covered area, with the additional advantage that the Landsat 7 band 8 (LB8) classification detects details in the extent of individual snowfields. This new application and the insights documented here support the use of Landsat 7 band 8 for snow-cover investigations in the future.
A comparison of Eulerian and Lagrangian methods for dating in numerical ice-sheet models
Authors: Rybak Oleg , Huybrechts Philippe
Published: November 2007

Accurate dating in ice sheets is required for a correct interpretation of palaeoclimatic records and for incorporation of material characteristics in the flow law which depend on ice age. In this paper, we make a comparison between a Lagrangian and Eulerian approach to the ice advection problem in numerical ice-sheet models. This comparison is first performed for a schematic two-dimensional ice sheet of Nye–Vialov type with a prescribed stationary velocity field. Severalcases are examined which incorporate basal melting, basal sliding and an undulating bed. A further comparison is made with an analytical solution for the ice divide. Both methods are also applied in a thermomechanical model of the Antarctic ice sheet for steady-state present-day conditions. Our main conclusion is that, for similar discretization parameters, the Lagrangian method produces less error than an Eulerian approach using a second-order upwinding finite-difference scheme, though the difference is small (<1%) for the largest part of the model domain. However, problems with the Lagrangian approach are introduced by the dispersion of tracers, necessitating the use of interpolation procedures that are a main source of additional error. It is also shown that a cubic-spline approximation of Lagrangian trajectories improves accuracy, but such a method is computationally hardly applicable in large-scale ice-sheet models.
Relationship between topography and flow in the north polar cap on Mars
Authors: Hvidberg Christine Schøtt
Published: November 2007

Assuming that the permanent north polar cap of Mars consists of flowing water ice, the relationship between topography and flow is examined along a profile extending from the pole in the 160° E direction This profile is intersected by scarps and troughs that are characteristic of the north polar cap The flow is calculated by a finite-element ice-flow model which includes divergence of the flow, longitudinal stresses and temperature effects. Ice-flow velocities are generally on the order of 0.1–1 mm a–1 but are enhanced at scarps and troughs to cm a–1. Ice flow smooths out the troughs. Troughs affect the flow to the bottom of the cap. Beneath a trough, ice is dragged upward. Longitudinal stresses are able to drag the lowest part of the ice past smaller troughs. At the pole-facing side of major troughs, ice is stagnant or flows slowly poleward. Implications for formation mechanisms of scarps and troughs are discussed.
Ice-flow measurements and deformation at marginal shear zones on Sørsdal Glacier, Ingrid Christensen Coast, East Antarctica
Authors: Patrick Benjamin A. , Corvino Adrian F. , Wilson Christopher J.L.
Published: November 2007

Observations of crevasse and crevasse trace geometry recorded along marginal shear zones of Sørsdal Glacier, East Antarctica, are presented with fine-spatial-resolution measurements of ice flow collected at three selected study sites. Strain grids established at each site, comprising 254 points, were repeatedly surveyed during the summers 2000/01 and 2001/02 using a semi-kinematic global positioning system technique with relative coordinate precisions at the order of ±2 cm in horizontal and ±5 cm in vertical. The annual results show ice-flow velocities of 2–114 m a–1 across a 2.7 km section of the Sørsdal margin. Comparable ice-flow velocities were also obtained using a Doppler system DORIS. At one study site, covering a planar area of 0.04 km2, a preliminary comparison is made between the crevasse pattern and strain-rate tensors computed for 64 discrete points using the method developed by Nye (1959). The comparison indicates that the most recent crevasses are directly related to the principal strain rates in this zone of simple shear.
Interannual velocity variations and recent calving of Thwaites Glacier Tongue, West Antarctica
Authors: Rabus Bernhard T. , Lang Oliver , Adolphs Ute
Published: November 2007

The surface velocity of Thwaites Glacier (TG), West Antarctica, during the period 1992–2000 is measured with synthetic aperture radar feature-tracking techniques. We find no indication of interannual velocity variations of the grounded ice further than about 20 km inland of the grounding line. The velocity of the floating TG Tongue shows cyclicalvariations with an amplitude of 10%; a minimum around 1997 is bracketed by similarly sized maxima in 1995 and 2000. The observed velocity variations can be explained by time-dependent rotation and deformation superimposed on the steady flow of TG Tongue. The orientation of the rotation is clockwise during the entire observation period; the mean center of the rotation is close to a small ice rise, situated at the east side of the tongue about 20 km past the grounding line. The recent calving of TG Tongue in February 2002 is consistent with continued clockwise rotation that eventually led to cracking from west to east across the tongue. The rotation and deformation of TG Tongue is caused by forces unrelated to glacier dynamics. Analysis of European Centre for Medium-Range Weather Forecasts wind data suggests a synoptic-scale origin for the external forcing that causes the rotation.
Observational verification of predicted increase in bedrock-to-surface amplitude transfer during a glacier surge
Authors: Hilmar Gudmundsson G. , Ađalgeirsdóttir Gudfinna , Björnsson Helgi
Published: November 2007

The amplitude ratio between surface and bedrock topography has been predicted to depend strongly on the ratio of deformational velocity to mean basal sliding velocity. Observations made prior to and during a surge of Tungnaárjökull, Vatnajökull ice cap, Iceland, allow this prediction to be tested. During the surge, the ratio of internal deformational velocity and basal sliding (slip ratio) changed from about unity to a few hundred. The amplitude ratio changed from about 0.1 to about 0.7. This increase in amplitude ratio is in good overall agreement with predictions based on an analytical perturbation analysis for a linearly viscous medium which includes the effects of horizontal deviatoric stresses on glacier flow. An increase in amplitude ratio of this magnitude is not predicted by a similarly linearized analysis that employs the commonly used shallow-ice approximation. The strong increase in transfer amplitude observed in the surge of Tungnaárjökull is a clear illustration of the effects of horizontal stress transmission on glacier flow reported here for the first time.
Observation of internal structures of snow covers with a ground-penetrating radar
Authors: Yamamoto Tatsuya , Matsuoka Kenichi , Naruse Renji
Published: November 2007

To complement a technique to detect internal structures of seasonal snow covers and glacier firn with ground-penetrating radar (GPR), we carried out calibration experiments and an observation of winter snow cover (5.7m thick dry snow with numerous ice layers) with an 800 MHz GPR. In particular, we aimed to discriminate periodic noise, which is inherent in GPR, from radar echoes and to obtain a relationship between the observed reflection strength and the magnitude of density contrasts. Experiments were done in air to evaluate noise levels and receiver characteristics of this system. Based on these, we removed noise from radar echoes in the snow-cover observation. We recognized numerous marked echoes in a noise-free radargram. The depths of these echoes coincided roughly with those of large density contrasts observed in the snow pit. Thus, we argue that the echoes correspond to thin ice layers. Furthermore, the minimum density contrasts detected by this GPR are found to vary from about 100 to 250 kgm–3 at 1–6m depth in the seasonal snow cover.
Risk assessment in avalanche-prone areas
Authors: Barbolini Massimiliano , Cappabianca Federica , Savi Fabrizio
Published: November 2007

This paper addresses the problem of defining a proper method for formal risk analysis in avalanche-prone areas. In this study, risk is defined as the annual probability of being killed by an avalanche for someone living or working permanently in a building under a hazardous hillside. A new methodology to estimate the hazard component of avalanche risk based on the use of dynamic models is introduced. This approach seems to have some advantages over the current methods based on statistical analysis of historic avalanche data. The vulnerability component of risk is formulated as a function of avalanche velocity, according to previous formulations. However, given the lack of knowledge on how avalanche impact damages structures and causes fatalities, the effect on the resulting risk mapping of using different vulnerability relations is explored. The potential of the proposed approach for evaluating the residual risk after the implementation of defensive structural work is discussed.
A re-analysis of the 58 year mass-balance record of Storglaciären, Sweden
Authors: Holmlund Per , Jansson Peter , Pettersson Rickard
Published: November 2007

The use of glacier mass-balance records to assess the effects of glacier volume change from climate change requires high-quality data. The methods for measuring glacier mass balance have been developed in tandem with the measurements themselves, which implies that the quality of the data may change with time. We have investigated such effects on the mass-balance record of Storglaciären, Sweden, by re-analyzing the records using a better map base and applying successive maps over appropriate time periods. Our results show that errors <0.8 m occur during the first decades of the time series. Errors decrease with time, which is consistent with improvements in measurement methods. Comparison between the old and new datasets also shows improvements in the relationships between net balance, equilibrium-line altitude and summer temperature. A time-series analysis also indicates that the record does not contain longer-term (>10 year) oscillations. The pseudo-cyclic signal must thus be explained by factors other than cyclically occurring phenomena, although the record may still be too short to establish significant signals. We strongly recommend re-analysis of long mass-balance records in order to improve the mass-balance records used for other analyses.
Assessment of the surface mass balance along the K-transect (Greenland ice sheet) from satellite-derived albedos
Authors: Greuell Wouter , Oerlemans Johannes
Published: November 2007

This paper explores the potential of using satellite-derived albedos to estimate the surface mass balance of the Kangerlussuaq transect (K-transect; Greenland ice sheet). We first retrieved surface albedos from Advanced Very High Resolution Radar data by using, among other techniques, a new cloud detection algorithm based on the relation between brightness temperature and surface elevation. We then computed the ‘satellite-derived mass balance’ (bsat) from the mean albedo for the transect, by taking fixed values for atmospheric transmissivity and the longwave and turbulent fluxes. We found that bsat explains 7 1% of the variance in 13 years of stake mass-balance measurements (bm). Our method also provides good estimates of the magnitude of the interannual variability in bm. The performance of the method degrades considerably without correction for anisotropic reflection at the surface and recalibration of the satellite sensors with dry snow at the top of the ice sheet. Sensitivity tests indicate that the method’s performance is hardly sensitive to uncertainties in parameters. Therefore, we expect that the method could be successfully applied on other glaciers and parts of ice sheets and ice caps, especially where accumulation rates are relatively small. We show that the investigated method performs best just below the mean equilibrium-line altitude.
Variation in glacier length and ice volume of Rabots Glaciär, Sweden, in response to climate change, 1910–2003
Authors: Brugger Keith A. , Refsnider Kurt A. , Whitehill Matthew F.
Published: November 2007

Historical records, photographs, maps and measurements were used to determine changes in the length, geometry and volume of Rabots Glaciär, Sweden, in response to a ∼1°C warming that occurred early in the 20th century. The glacier’s initial rate of retreat from its 1910 maximum was ~2.0 m a–1. After a sharp increase to ∼11.7 m a–1 between 1933 and 1946, the mean retreat rate decreased to ∼5.5 m a-1 between 1946 and 1959. Thereafter the rate of retreat increased to ∼11.0 m a-1 and has remained relatively constant to the present time. Concomitant decreases in ice volume were estimated to be 77.3 × 106m3 between 1910 and 1959, 51.1 × 106m3 between 1959 and 1980, at least 10.4 × 106m3 between 1980 and 1989, and 14.4 × 106m3 between 1989 and 2003. The total volume change over the last 93 years is estimated at ∼153.2 × 106m3 corresponding to 1.6 × 106m3a–1.. The magnitude of the ongoing changes in length and volume suggests that Rabots Glaciär has not yet completed its response to the earlier climatic warming. In contrast, several nearby glaciers, most notably Storglaciären, have completed their adjustments and established new steady-state profiles as a result of having shorter response times.