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1.
J Geophys Res Atmos ; 121(10): 5411-5429, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27478717

RESUMO

Large-scale modeling of glacier mass balance relies often on the output from regional climate models (RCMs). However, the limited accuracy and spatial resolution of RCM output pose limitations on mass balance simulations at subregional or local scales. Moreover, RCM output is still rarely available over larger regions or for longer time periods. This study evaluates the extent to which it is possible to derive reliable region-wide glacier mass balance estimates, using coarse resolution (10 km) RCM output for model forcing. Our data cover the entire Svalbard archipelago over one decade. To calculate mass balance, we use an index-based model. Model parameters are not calibrated, but the RCM air temperature and precipitation fields are adjusted using in situ mass balance measurements as reference. We compare two different calibration methods: root mean square error minimization and regression optimization. The obtained air temperature shifts (+1.43°C versus +2.22°C) and precipitation scaling factors (1.23 versus 1.86) differ considerably between the two methods, which we attribute to inhomogeneities in the spatiotemporal distribution of the reference data. Our modeling suggests a mean annual climatic mass balance of -0.05 ± 0.40 m w.e. a-1 for Svalbard over 2000-2011 and a mean equilibrium line altitude of 452 ± 200 m above sea level. We find that the limited spatial resolution of the RCM forcing with respect to real surface topography and the usage of spatially homogeneous RCM output adjustments and mass balance model parameters are responsible for much of the modeling uncertainty. Sensitivity of the results to model parameter uncertainty is comparably small and of minor importance.

2.
Ambio ; 40(6): 566-74, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21954720

RESUMO

A unique long term, 49-year record (divided into three time periods 1961-1976, 1977-1992, and 1993-2009) of snow profile stratigraphy from the Swedish sub Arctic, was analyzed with a focus on changes in snow characteristics. The data set contained grain size, snow layer hardness, grain compactness, and snow layer dryness, observed every second week during the winter season. The results showed an increase in very hard snow layers, with harder snow in early winter and more moist snow during spring. There was a striking increase in the number of observations with very hard snow at ground level over time. More than twice as many occasions with hard snow at ground level were observed between 1993 and 2009 compared to previous years, which may have a significant effect on plants and animals. The changes in snow characteristics are most likely a result of the increasing temperatures during the start and the end of the snow season.


Assuntos
Mudança Climática , Neve , Regiões Árticas , Estações do Ano , Suécia , Temperatura
3.
Ambio ; 40(6): 705-16, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21954732

RESUMO

Understanding the responses of tundra systems to global change has global implications. Most tundra regions lack sustained environmental monitoring and one of the only ways to document multi-decadal change is to resample historic research sites. The International Polar Year (IPY) provided a unique opportunity for such research through the Back to the Future (BTF) project (IPY project #512). This article synthesizes the results from 13 papers within this Ambio Special Issue. Abiotic changes include glacial recession in the Altai Mountains, Russia; increased snow depth and hardness, permafrost warming, and increased growing season length in sub-arctic Sweden; drying of ponds in Greenland; increased nutrient availability in Alaskan tundra ponds, and warming at most locations studied. Biotic changes ranged from relatively minor plant community change at two sites in Greenland to moderate change in the Yukon, and to dramatic increases in shrub and tree density on Herschel Island, and in subarctic Sweden. The population of geese tripled at one site in northeast Greenland where biomass in non-grazed plots doubled. A model parameterized using results from a BTF study forecasts substantial declines in all snowbeds and increases in shrub tundra on Niwot Ridge, Colorado over the next century. In general, results support and provide improved capacities for validating experimental manipulation, remote sensing, and modeling studies.


Assuntos
Mudança Climática , Ecossistema , Monitoramento Ambiental , Regiões Árticas , Desenvolvimento Vegetal
4.
Environ Sci Technol ; 44(19): 7405-10, 2010 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-20839863

RESUMO

Brominated flame retardants (BFRs) have been found in Arctic wildlife, lake sediment, and air. To identify the atmospheric BFR deposition history on Svalbard, Norway, we analyzed 19 BFRs, including hexabromocyclododecane (HBCD), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), and 15 polybrominated diphenyl ether congeners (PBDE) in the upper 34 m of an ice core (representing 1953-2005) from Holtedahlfonna, the western-most ice sheet on Svalbard. All of the non-PBDE compounds were detected in nearly continuous profiles in the core. Seven PBDEs were not observed above background (28, 47, 66, 100, 99, 154, 153), while 4 were found in 1 or 2 of 6 segments (17, 85, 138, 183). BDEs-49, 71, 190, 209 had nearly continuous profiles but only BDE-209 in large amounts. The greatest inputs were HBCD and BDE-209, 910, and 320 pg cm(-2) yr(-1) from 1995-2005. DBDPE, BTBPE, and PBEB show nearly continuous input growth in recent core segments, but all were <6 pg cm(-2) yr(-1). Long-range atmospheric processes may have moved these particle-bound BFRs to the site, probably during the Arctic haze season. Average air mass trajectories over 10 years show >75% of atmospheric flow to Holtedahlfonna coming from Eurasia during haze periods (March and April).


Assuntos
Bromo/química , Poluentes Ambientais/análise , Retardadores de Chama/análise , Gelo/análise , Noruega
5.
Bull World Health Organ ; 79(5): 382-7, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11417032

RESUMO

OBJECTIVE: To study the cultural differences in moral disengagement, which lends support to attitudes used to justify violence. METHODS: We carried out classroom surveys of a total of 3122 students in the USA (Houston, TX, and Washington, DC) and in four European countries--Estonia (Tartu), Finland (Helsinki), Romania (Satu Mare) and the Russian Federation (St Petersburg). Data were also taken from a random sample telephone survey of 341 young adults (aged 18-35 years) in Texas, USA. Ten distinct groups were studied. Seven questions were common to all the surveys, using identical statements about the participants' agreement with attitudes relating to war, diplomacy, killing, and the punishment of children. FINDINGS: The US students were more likely than those in Europe to agree with the following statements: "War is necessary" (20% vs 9%), "A person has the right to kill to defend property" (54% vs 17%), and "Physical punishment is necessary for children" (27% vs 10%). Justification of war and killing was less common among females than males in all groups; other differences within the US groups and the European groups were smaller than the differences between the US and European groups. CONCLUSION: The results confirm the gap between the US and European groups in moral disengagement attitudes and tendencies that could lead to deadly violence.


Assuntos
Atitude , Educação Infantil/psicologia , Punição , Violência/psicologia , Guerra , Adolescente , Adulto , Criança , Comparação Transcultural , Estônia , Feminino , Finlândia , Humanos , Masculino , Romênia , Federação Russa , Inquéritos e Questionários , Texas
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