bluuebunny/crossref_metadata_2025_split huggingface dataset:
Snowmelt runoff processes in a headwater lake and its catchment, subarctic Canadian Shield
Authors: Mielko Corrinne , Woo Ming‐ko 
Published: February 2006

AbstractDuring the snowmelt season, surface runoff into northern Canadian Shield lakes is governed by the distribution of snow and its ablation, storage in catchment slopes and valleys, and flow delivery from uplands, bottomlands and from upper lakes. For the lake studied, time lags exist between the commencement of snowmelt and the arrival of runoff to the lake, with evaporation from the uplands and bottomlands consuming some of the meltwater produced. Inflow from an upper lake is delayed. With all these inputs, the lake becomes flooded, first forming a moat, followed by an expansion of the open water areas, which are subject to evaporation loss. Lake outflow begins when water level rises above the outlet threshold. For the snowmelt season, outflow constitutes 40% of total melt and rainfall. The lake itself is a major storage that continues to maintain outflow until the lake level drops below the threshold in early summer, after which flow ceases. Snowmelt is the main period when runoff is generated from the headwater catchment to replenish storage depleted in the previous summer, and to produce flow along the Shield valley that contains a chain of lakes. Copyright © 2006 John Wiley & Sons, Ltd.
Blowing snow studies in the Canadian Arctic Shelf Exchange Study, 2003–04
Authors: Savelyev S. A. , Gordon M. , Hanesiak J. , Papakyriakou T. , Taylor P. A. 
Published: February 2006

AbstractBetween mid January and early May 2004, during the Canadian Arctic Shelf Exchange Study 2003–04 expedition, we conducted a field project in which we deployed blowing‐snow particle counters, visibility sensors, a FlowCapt device, snow bags, an electric field meter and other instruments related to the observation of drifting and blowing snow on first‐year ice in Franklin Bay, Northwest Territories, Canada. Average snow depth was 7 cm at the beginning of the campaign and increased to 17 cm towards the end. Snow density in the first 8 cm of snow cover varied from 80 to 450 g m−3, with a median value of 240 g m−3. Basic results will be presented that relate particle counter profiles, wind speed and other data to visibility. We discuss threshold conditions for blowing snow, heat and water vapour fluxes and the electric field. Relative humidity with respect to ice was generally greater than 95% and sublimation rates are believed to have been low. Copyright © 2006 John Wiley & Sons, Ltd.
Measurement sampling and scaling for deep montane snow depth data
Authors: Fassnacht S. R. , Deems J. S. 
Published: February 2006

AbstractThe resolution of snow depth measurements was scaled from a nominal horizontal resolution of approximately 1·5 m to 3, 5, 10, 20, and 30 m using averaging (AVG) and resampling with a uniform random stratified sampling (RSS) scheme. The raw snow depth values were computed from airborne light detection and ranging data by differencing summer elevation measurements from winter snow surface elevations. Three montane study sites from the NASA Cold Lands Processes Experiment, each covering an 1100 m × 1100 m area, were used.To examine scaling, log–log semi‐variograms with 50 log‐width bins were created for both of the different subsetting methods, i.e. RSS and AVG. From the raw data, a scale break, going from a structured to a nearly spatially random system, was observed in each of the log–log variograms. For each site, the scale break was still detectable at slightly greater than the resampling resolution for the RSS scheme, but at approximately twice the subsetting resolution for the AVG scheme. The resolution required to identify the scale break was still from 5 to 10 m, depending upon the location and sampling method. Copyright © 2006 John Wiley & Sons, Ltd.
Solar power for an Antarctic rover
Authors: Lever J. H. , Ray L. R. , Streeter A. , Price A. 
Published: February 2006

AbstractSensors mounted on mobile robots could serve a variety of science missions in Antarctica. Although weather conditions can be harsh, Antarctic snowfields offer unique conditions to facilitate long‐distance robot deployment: the absence of obstacles, firm snow with high albedo, and 24 h sunlight during the summer. We have developed a four‐wheel‐drive, solar‐powered rover that capitalizes on these advantages. Analyses and field measurements confirm that solar power reflected from Antarctic snow contributes 30–40% of the power available to a robot consisting of a five‐side box of solar panels. Mobility analyses indicate that the 80 kg rover can move at 0·8 m s−1 during clear sky conditions on firm snow into a 5 m s−1 headwind, twice the speed needed to achieve the design target of 500 km in 2 weeks. Local winter tests of the chassis demonstrated good grade‐climbing ability and lower than predicted rolling resistance. Tests of the completed robot occurred in Greenland in 2005. Copyright © 2006 John Wiley & Sons, Ltd.
Boundary‐layer growth over snow and soil patches: field observations
Authors: Granger Raoul J. , Essery Richard , Pomeroy John W. 
Published: February 2006

AbstractMuch of the snowmelt season is characterized by a patchy surface; differential heating of the snow and snow‐free surfaces results in a significant horizontal transport of energy that affects and contributes to the snowmelt. The calculation of the rate of energy advection requires some knowledge of the behaviour of the thermal boundary layer over the patches of snow and snow‐free surfaces. We present the results from a series of field observations of the rate of growth of the thermal boundary layer over snow and snow‐free patches. The results confirm that the boundary‐layer growth can be described by a power function of the distance from the leading edge of the patch. For the case of the thermal boundary layer over a snow patch within a bare field, the boundary‐layer growth is affected by the upwind surface roughness; the thermal boundary layer over a snow patch within a ‘rough’ field grows much more quickly than that in a ‘smooth’ field. Relationships are derived and presented for the parameterization of the boundary‐layer growth as a function of distance and upwind surface roughness. Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Shrub tundra snowmelt
Authors: Pomeroy J. W. , Bewley D. S. , Essery R. L. H. , Hedstrom N. R. , Link T. , Granger R. J. , Sicart J. E. , Ellis C. R. , Janowicz J. R. 
Published: February 2006

AbstractObservations of land surface and snowpack energetics and mass fluxes were made over arctic shrub tundra of varying canopy height and density using radiometers, eddy covariance flux measurements, and snow mass changes from snow surveys of depth and density. Over several years, snow accumulation in the shrubs was found to be consistently higher than in sparse tundra due to greater retention of snowfall by all shrubs and wind redistribution of snowfall to tall shrubs. Where snow accumulation was highest due to snow redistribution, shrubs often became buried by the end of winter. Three classes of shrub‐snow interactions were observed: tall shrubs that were exposed over snow, tall shrubs that were bent over and buried by snow, and short shrubs buried by snow. Tall shrubs buried by snow underwent ‘spring‐up’ during melt. Though spring‐up was episodic for a single shrub, over an area it was a progressive emergence from early to mid melt of vegetation that dramatically altered the radiative and aerodynamic properties of the surface. Short shrubs were exposed more rapidly once snow depth declined below shrub height, usually near the end of melt. Net radiation increased with increasing shrub due to the decreased reflectance of shortwave radiation overwhelming the increased longwave emission from relatively warm and dark shrubs. Net radiation to snow under shrubs was much smaller than that over shrubs, but was greater than that to snow with minimal shrub exposure, in this case the difference was due to downward longwave radiation from the canopy exceeding the effect of attenuated shortwave transmission through the canopy. Because of reduced turbulent transfer under shrub canopies and minimal water vapour contributions from the bare shrub branches, sublimation fluxes declined with increasing shrub exposure. In contrast, sensible heat fluxes to the shrub surface became more negative and those to the underlying snow surface more positive with increasing shrub exposure, because of relatively warm shrub branches, particularly on clear days. From well‐exposed tall shrubs, both a large upward sensible heat flow from shrub to atmosphere and a downward flow that contributed substantially to snowmelt were detected. As a result of radiative and turbulent transfer in shrub canopies, melt rates increased with shrub exposure. However, shrub exposure was not a simple function of shrub height or presence, and the transition to shrub‐exposed landscape depended on initial snow depth, shrub height, shrub species and cumulative melt, and this in turn controlled the melt energetics for a particular site. As a result of these complex interactions, observations over several years showed that snowmelt rates were generally, but not always, enhanced under shrub canopies in comparison with sparsely vegetated tundra. Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Intra‐basin variability of snowmelt water balance calculations in a subarctic catchment
Authors: McCartney Stephen E. , Carey Sean K. , Pomeroy John W. 
Published: February 2006

AbstractThe intra‐basin variability of snowmelt and melt‐water runoff hydrology in an 8 km2 subarctic alpine tundra catchment was examined for the 2003 melt period. The catchment, Granger Creek, is within the Wolf Creek Research Basin, Yukon, which is typical of mountain subarctic landscapes in northwestern Canada. The study catchment was segmented into nine internally uniform zones termed hydrological response units (HRUs) based on their similar hydrological, physiographic, vegetation and soil properties. Snow accumulation exhibited significant variability among the HRUs, with greatest snow water equivalent in areas of tall shrub vegetation. Melt began first on southerly exposures and at lower elevations, yet average melt rates for the study period varied little among HRUs with the exception of those with steep aspects. In HRUs with capping organic soils, melt water first infiltrated this surface horizon, satisfying its storage capacity, and then percolated into the frozen mineral substrate. Infiltration and percolation into frozen mineral soils was restricted where melt occurred rapidly and organic soils were thin; in this case, melt‐water delivery rates exceeded the frozen mineral soil infiltration rate, resulting in high runoff rates. In contrast, where there were slower melt rates and thick organic soils, infiltration was unlimited and runoff was suppressed. The snow water equivalent had a large impact on runoff volume, as soil storage capacity was quickly surpassed in areas of deep snow, diverting the bulk of melt water laterally to the drainage network. A spatially distributed water balance indicated that the snowmelt freshet was primarily controlled by areas with tall shrub vegetation that accumulate large quantities of snow and by alpine areas with no capping organic soils. The intra‐basin water balance variability has important implications for modelling freshet in hydrological models. Copyright © 2006 John Wiley & Sons, Ltd.
Estimating the snow water equivalent on the Gatineau catchment using hierarchical Bayesian modelling
Authors: Seidou Ousmane , Fortin Vincent , St‐Hilaire André , Favre Anne‐Catherine , Adlouni Salaheddine El , Bobée Bernard 
Published: February 2006

AbstractOne of the most important parameters for spring runoff forecasting is the snow water equivalent on the watershed, often estimated by kriging using in situ measurements, and in some cases by remote sensing. It is known that kriging techniques provide little information on uncertainty, aside from the kriging variance. In this paper, two approaches using Bayesian hierarchical modelling are compared with ordinary kriging; Bayesian hierarchical modelling is a flexible and general statistical approach that uses observations and prior knowledge to make inferences on both unobserved data (snow water equivalent on the watershed where there is no measurements) and on the parameters (influence of the covariables, spatial interactions between the values of the process at various sites). The first approach models snow water equivalent as a Gaussian spatial process, for which the mean varies in space, and the other uses the theory of Markov random fields. Although kriging and the Bayesian models give similar point estimates, the latter provide more information on the distribution of the snow water equivalent. Furthermore, kriging may considerably underestimate interpolation error. Copyright © 2006 Environment Canada. Published by John Wiley & Sons, Ltd.
Comparison of local scale measured and modelled brightness temperatures and snow parameters from the CLPX 2003 by means of a dense medium radiative transfer theory model
Authors: Tedesco Marco , Kim Edward J. , Cline Don , Graf Tobias , Koike Toshio , Armstrong Richard , Brodzik Mary J. , Hardy Janet 
Published: February 2006

AbstractSome 27 years of passive microwave satellite observations have demonstrated the value of remote sensing for cryospheric applications, albeit at regional to hemispheric scales due to the relatively large sensor footprints (e.g. ∼25 km × 25 km for the advanced microwave scanning radiometer). At the other extreme there is the primarily local‐scale in situ experience of the snow community. Until higher‐resolution sensors become available, understanding the effects of sub‐pixel heterogeneity and the downscaling of observations remains an important topic.In order to provide a baseline for performing scaling studies and for future radiance‐based hydrological assimilation schemes, an evaluation of snowpack forward radiance modelling at the plot scale (least heterogeneous scale) is carried out. Snow microwave radiance models based on dense medium radiative transfer (DMRT) theory incorporate a high degree of physical fidelity, yet dense medium models are particularly sensitive to snowpack structural parameters such as grain size, density, and depth (parameters that may vary substantially within a snowpack). The DMRT performance is evaluated through the use of a fitting technique with respect to snow grain size, a hydrologically important parameter related to the total amount of melt water stored in a snowpack, snowpack metamorphism, vertical energy transport and melt dynamics, as well as various quantities useful in surface energy balance studies. All remaining snow input parameters to the model are derived from snow pit measurements. Model‐predicted radiances are evaluated using microwave brightness measurements collected during the NASA Cold Land Process Experiment (CLPX) by the University of Tokyo's Ground‐Based Microwave Radiometer‐7 (GBMR‐7) system at 18·7, 36·5, and 89 GHz, with incidence angles ranging from 30 to 70 °. The detailed CLPX microwave and snow data provide an excellent opportunity to gain insight into the strengths and weaknesses of this approach. Copyright © 2006 John Wiley & Sons, Ltd.
Evaluation of gridded snow water equivalent and satellite snow cover products for mountain basins in a hydrologic model
Authors: Dressler K. A. , Leavesley G. H. , Bales R. C. , Fassnacht S. R. 
Published: February 2006

AbstractThe USGS precipitation‐runoff modelling system (PRMS) hydrologic model was used to evaluate experimental, gridded, 1 km2 snow‐covered area (SCA) and snow water equivalent (SWE) products for two headwater basins within the Rio Grande (i.e. upper Rio Grande River basin) and Salt River (i.e. Black River basin) drainages in the southwestern USA. The SCA product was the fraction of each 1 km2 pixel covered by snow and was derived from NOAA advanced very high‐resolution radiometer imagery. The SWE product was developed by multiplying the SCA product by SWE estimates interpolated from National Resources Conservation Service snow telemetry point measurements for a 6 year period (1995‐2000). Measured SCA and SWE estimates were consistently lower than values estimated from temperature and precipitation within PRMS. The greatest differences occurred in the relatively complex terrain of the Rio Grande basin, as opposed to the relatively homogeneous terrain of the Black River basin, where differences were small. Differences between modelled and measured snow were different for the accumulation period versus the ablation period and had an elevational trend. Assimilating the measured snowfields into a version of PRMS calibrated to achieve water balance without assimilation led to reduced performance in estimating streamflow for the Rio Grande and increased performance in estimating streamflow for the Black River basin. Correcting the measured SCA and SWE for canopy effects improved simulations by adding snow mostly in the mid‐to‐high elevations, where satellite estimates of SCA are lower than model estimates. Copyright © 2006 John Wiley & Sons, Ltd.
Recent trends in Canadian lake ice cover
Authors: Duguay Claude R. , Prowse Terry D. , Bonsal Barrie R. , Brown Ross D. , Lacroix Martin P. , Ménard Patrick 
Published: February 2006

AbstractRecent studies have shown that ice duration in lakes and rivers over the Northern Hemisphere has decreased over the 19th and 20th centuries in response to global warming. However, lake ice trends have not been well documented in Canada. Because of its size, considerable variability may exist in both freeze‐up and break‐up dates across the country. In this paper, results of the analysis of recent trends (1951–2000) in freeze‐up and break‐up dates across Canada are presented. Trends toward earlier break‐up dates are observed for most lakes during the time periods of analysis which encompass the 1990s. Freeze‐up dates, on the other hand, show few significant trends and a low degree of temporal coherence when compared with break‐up dates. These results are compared with trends in autumn and spring 0 °C isotherm dates over the time period 1966–95. Similar spatial and temporal patterns are observed, with generally significant trends toward earlier springs/break‐up dates over most of western Canada and little change in isotherm and freeze‐up dates over the majority of the country in autumn. Strong correlations (r > 0·5) between 0 °C isotherm dates and freeze‐up/break‐up dates at many locations across the country reveal the high synchrony of these variables. These results are also consistent with more recent observations of other cryospheric and atmospheric variables that indicate, in particular, a general trend toward earlier springs in the latter part of the 20th century. The results of this study provide further evidence of the robustness of lake ice as a proxy indicator of climate variability and change. Copyright © 2006 John Wiley & Sons, Ltd.
Docetaxel and gemcitabine combination in 133 advanced soft‐tissue sarcomas: A retrospective analysis
Authors: Bay Jacques‐Olivier , Ray‐Coquard Isabelle , Fayette Jérôme , Leyvraz Serge , Cherix Stephane , Piperno‐Neumann Sophie , Chevreau Christine , Isambert Nicolas , Brain Etienne , Emile Georges , Le Cesne Axel , Cioffi Angela , Kwiatkowski Fabrice , Coindre Jean‐Michel , Bui Nguyon Binh , Peyrade Frédéric , Blay Jean‐Yves ,   for the Groupe Sarcome Français
Published: February 2006

AbstractAdvanced soft‐tissue sarcomas are usually resistant to cytotoxic agents such as doxorubicin and ifosfamide. Antitumor activity has been observed for gemcitabine and docetaxel combination. We conducted a retrospective study on 133 patients (58 males/75 females) with unresectable or metastatic soft‐tissue sarcoma. The median age at diagnosis was 51.7 (18–82), with 76 patients with leiomoyosarcoma and 57 patients with other histological subtypes. The initial localizations were limb (44), uterine (32), retroperitoneal (23) and organs or bone (34). Patients received 900 mg/m2 of gemcitabine (days 1 and 8) over 90 min plus 100 mg/m2 of docetaxel (day 8), intravenously every 21 days. Gemcitabine/docetaxel combination was well tolerated with an overall response of 18.4% and with no clear statistical difference between leiomyosarcomas and other histological subtypes (24.2% versus 10.4% (p = 0.06)). No difference was found between uterine soft‐tissue sarcomas versus others. The median overall survival was 12.1 months (1–28). Better overall survival was correlated with leiomyosarcoma (p = 0.01) and with the quality of the response, even for patients with stable disease (p < 10−4). No statistical difference was found for the initial localization. Response to treatment and overall survival were better for patients in World Health Organization (WHO) performance status classification (PS) 0 at baseline versus patients in WHO PS‐1, 2 or 3 (p = 0.023 and p < 10−4, respectively). Gemcitabine/docetaxel combination was tolerable and demonstrated better response and survival for leiomyosarcoma, especially for patients in WHO PS‐0 at baseline. For the other histological subtypes, the response was not encouraging, but the survival for patients in response or stable suggests further investigation. © 2006 Wiley‐Liss, Inc.
Identification of limited regions of genetic aberrations in patients affected with Wilms' tumor using a tiling‐path chromosome 22 array
Authors: Benetkiewicz Magdalena , de Ståhl Teresita Díaz , Gördör Anita , Pfeifer Susan , Wittmann Stefanie , Gessler Manfred , Dumanski Jan P. 
Published: February 2006

AbstractWilms' tumor (WT) is one of the most common solid tumors of childhood. The genetics of this disorder is complex and few studies have suggested allelic loss of chromosome 22 as a frequent aberration. To assess tumor‐ and possible germline‐specific regions affected with gene copy number variations on this chromosome, we applied a high‐resolution genomic clone‐based chromosome 22 array to a series of 28 WT samples and the paired blood‐derived DNA of the patients. The group of tumors was enriched for cases with metastases, relapse or fatal outcome, criteria that were expected to yield a higher number of alterations on chromosome 22. Overall, the array‐based form of comparative genomic hybridization (array‐CGH) analysis revealed genomic changes in 53% (15 out of 28) of cases. We identified hemizygous deletion of the whole arm of 22q in 3 tumors (11%). Furthermore, a complex amplifier genotype was detected in 8 samples, presenting regions of gain along the chromosome, which defined 7 distinct minimal overlapping segments. The distribution of aberrations in 4 additional cases displaying regional genomic imbalances delimited 2 tumor suppressor/oncogene candidate loci, 1 in the proximal and the other in the terminal part of 22q. Analysis of these regions revealed the presence of several candidate genes that may play a role in the development of WT. These findings demonstrate the power of array‐CGH in the determination of DNA copy number alterations and further strength the notion that WT‐associated genes exist on this chromosome. © 2006 Wiley‐Liss, Inc.