Assessing streams in Germany with benthic invertebrates: selection of candidate metrics   总被引：3，自引：0，他引：3  

Daniel Hering  Carolin Meier  Claudia Rawer-Jost  Christian K. Feld  Regina Biss  Armin Zenker  Andrea Sundermann  Susanne Lohse  Jürgen Bhmer 《Limnologica》2004,34(4):398-415

The process of selecting invertebrate-based candidate metrics for the German stream assessment system is described. The aim was to identify metrics indicating degradation types other than organic pollution and acidification (“general degradation”). For 18 out of 24 German stream types a data base of roughly 2,000 benthic invertebrate samples was generated; for each sample 79 metrics were calculated. Data on land use in the catchment were compiled for all sampling sites, together with data on hydromorphology for many sampling sites. Hydromorphological and land use parameters, which describe a clear gradient in the data sets were identified by Non-metric Multidimensional Scaling (NMS). Correlation analyses between land use/hydromorphological parameters and metric results were calculated separately for the individual stream types. Among those metrics best indicating catchment- and hydromorphological degradation in the majority of stream types are: proportion of Ephemeroptera, Plecoptera and Trichoptera; proportion of Plecoptera (mainly suited for mountain streams); number of Plecoptera taxa; proportion of xenosaprobic taxa; proportion of epirhithral preferring taxa. Differences of metric correlations between stream types and between degradation types are discussed, leading to a list of candidate metrics for assessing German streams.  相似文献   

DETERMINATION OF FLUORINE, CHLORINE, BROMINE AND IODINE IN SEVEN GEOCHEMICAL REFERENCE SAMPLES     

Marcel LANGENAUER  Urs KRÄHENBÜHL  Verena FURRER  Armin WYTTENBACH 《Geostandards and Geoanalytical Research》1992,16(1):41-44

The concentrations of fluorine, chlorine, bromine and iodine of seven geochemical reference samples have been determined. Analytical techniques were neutron activation analysis for chlorine, bromine and iodine and ion-selective potentiometry for fluorine. After irradiation of the samples, these halogens were separated from the matrix elements by pyrohydrolysis in presence of vanadium (V) oxide. This extraction allows to measure the four halogens in the same sample.  相似文献   

Bemerkungen zur Hypothese zweier Sturmzeitringströme     

Armin Grafe  Adolf Best 《Pure and Applied Geophysics》1966,64(1):59-77

Summary For several years the theory of the main phase of geomagnetic storms takes into account the existence of two storm time ring currents which are thought to exist in different altitudes. This hypothesis is supported less by satellite data than by the analysis of recovery effects observed in the geomagnetic records, according to that the recovery phase should exist of two seperate single phases. In our opinion however the observational material seems not convincing enough, especially because material of one station only was used for the hitherto made investigations and no elimination of theSq-part was executed. A critical analysis of the observational material is by all means necessary, especially for the reason that already in literature extensive inferences of theDR2 ring current for the formation and the energy behaviour of theDP part were drawn. For the investigation of recovery effects it is necessary to use additionally to records of equatorial stations those of observatories in higher latitudes. TheSq-part has to be eliminated in the analysis. It is referred that new disturbances after the beginning of the recovery phase can feign two separated ring current effects. Some examples of the recovery phase will be discussed. They show that the observational material gives no necessity for the supposition of two separate strom time ring currents. Furthermore some theoretical considerations are opposite to this hypothesis. The charge exchange with thermical atoms of hydrogen is discussed to be a possible loss process. It is taken into account also the possibility to suppose a wide proton energy spectrum for explaining the recovery phase.

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Mitteilung aus dem Geomagnetischen Institut Potsdam, Nr. 226.  相似文献   

Climate change adaptation: a systematic review on domains and indicators     

Salehi  Shiva  Ardalan  Ali  Garmaroudi  Gholamreza  Ostadtaghizadeh  Abbas  Rahimiforoushani  Abbas  Zareiyan  Armin 《Natural Hazards》2019,96(1):521-550

In recent years, climate change has been one of the most complicated problems that human being has faced. Climate change adaptation (CCA) is considered to be an important component of risk management. In order to achieve adaptation, it is necessary to determine the indicators influencing adaptation in each community and this requires measurement and standard tools. The aim of this study is to determine and categorize the indicators of CCA. International electronic databases including Science Direct, Web of Science, Scopus, Google Scholar were investigated for only articles published in English language. In addition, Iranian databases including Irandoc, SID, and Magiran were investigated. There was no limitation on the methods of studies. Furthermore, snowball method was used for finding more articles while the ProQuest database was searched for related dissertations. The published documents from 1990 to November 2017 were gathered in this study. Out of 4439 publications initially search, 152 full texts were investigated. Finally, a total of 45 potentially relevant citations were included for full text review; in addition, fourteen other sources were investigated. Using snowball method, we found 24 other articles that were included in our final result. From the searches, 176 indicators were identified, while seven main domains were mentioned. Since in the articles, domains of adaptation are not in the form of a model, it is better to focus on this issue in the future and it seems that prioritizing and weighting domains in adaptation in different communities with different needs are an important issue.

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Triplets of quasars at high redshift – I. Photometric data     

M. Victoria Alonso  Georgina V. Coldwell  Ilona Söchting  Carlos Bornancini  Malcolm G. Smith  Diego García Lambas  Armin Rest 《Monthly notices of the Royal Astronomical Society》2008,385(4):2254-2260

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Climate change and modelling of extreme temperatures in Switzerland   总被引：3，自引：3，他引：0  

Boriss Siliverstovs  Rainald Ötsch  Claudia Kemfert  Carlo C. Jaeger  Armin Haas  Hans Kremers 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(2):311-326

This study models maximum temperatures in Switzerland monitored in twelve locations using the generalised extreme value (GEV) distribution. The parameters of the GEV distribution are determined within a Bayesian framework. We find that the parameters of the underlying distribution underwent a substantial change in the beginning of the 1980s. This change is characterised by an increase both in the level and the variability. We assess the likelihood of the heat wave of the summer 2003 using the fitted GEV distribution by accounting for the presence of a structural break. The estimation results do suggest that the heat wave of 2003 is not that statistically improbable if an appropriate methodology is used for dealing with nonstationarity.  相似文献   

Einige charakteristische Besonderheiten des geomagnetischen Sonneneruptionseffektes     

Armin Grafe 《Pure and Applied Geophysics》1958,40(1):172-179

Zusammenfassung Es werden die wichtigsten Resultate einer statischen Untersuchung des geomagnetischen Sonneneruptionseffektes wiedergegeben, der ein 65-jähriges Registriermaterial vom Observatorium Potsdam-Niemegk zugrunde liegt. Es zeigte sich einmal, daß diesfe-Häufigkeiten der 70-bis 80-jährigen Sonnenfleckenperiode folgen, und daß sie einen jahreszeitlichen Gang mit zwei Äquinoktialmaxima und einem extremen Sommerminimum besitzen. Zum anderen konnte die bekannte Ost-West-Asymmetrie der Sonnenflecken und Eruptionen auch für diesfe-erzeugenden Eruptionen nachgewiesen werden. Schließlich wurde noch eine Phasenverschiebung zwischenSQ- undsfe-Stromvektor gefunden.

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Summary The most important results of a statistical research of geomagneticsfe's are discussed, based on recordings of the observatory in Potsdam, Seddin and Niemegk during the last 65 years from 1890–1956. It is made evident that the frequency ofsfe's follows the sunspot period of 70–80 years and has an seasonal variation with two equinoctial-maxima and an extreme summer-minimun. Otherwise the well-known east-west-asymmetry of the sunspots and eruptions has been proved also for the eruptions producing thesfe's. Finally a lag of the phases betweenSQ- andsfe-current vector was found.

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Economic,institutional and technological uncertainties of emissions trading—a system dynamics modeling approach     

Irina Dolgopolova  Bo Hu  Armin Leopold  Stefan Pickl 《Climatic change》2014,124(3):663-676

System dynamics models are employed for analyzing the impact of different uncertainties on carbon emission trading–both on national and business levels. Economic, institutional and technological uncertainties significantly influence any country's benefits from emission permit trading. If a country participates in trading on the international market then the possible price range becomes the source of additional uncertainty. In the case of business investment decisions for implementing resource‐saving technology, our system dynamics model shows that the first‐mover investor will get significantly fewer advantages than his followers, which leads to delay in primary investment to the sector.  相似文献   

Properties of adjoint sea ice sensitivities to atmospheric forcing and implications for the causes of the long term trend of Arctic sea ice     

Nikolay V. Koldunov  Armin Köhl  Detlef Stammer 《Climate Dynamics》2013,41(2):227-241

Based on adjoint sensitivities of the coupled Massachusetts Institute of Technology ocean–sea ice circulation model, the potential influence of thermodynamic atmospheric forcing on the interannual variability of the September sea ice area (AREA) and volume (VOLUME) in the Arctic is investigated for the three periods 1980–1989, 1990–1999 and 2000–2009. Sensitivities suggest that only large forcing anomalies prior to the spring melting onset in May can influence the September sea ice characteristics while even small changes in the atmospheric variables during subsequent months can significantly influence September sea ice state. Specifically, AREA close to the ice edge in the Arctic seas is highly sensitive to thermodynamic atmospheric forcing changes from June to July. In contrast, VOLUME is highly sensitive to atmospheric temperature changes occurring during the same period over the central parts of the Arctic Ocean. A comparison of the sea ice conditions and sensitivities during three different periods reveals that, due to the strong decline of sea ice concentration and sea ice thickness, sea ice area became substantially more sensitive to the same amplitude thermodynamic atmospheric forcing anomalies during 2000–2009 relative to the earlier periods. To obtain a quantitative estimate of changes that can be expected from existing atmospheric trends, adjoint sensitivities are multiplied by monthly temperature differences between 1980s and two following decades. Strongest contributions of surface atmospheric temperature differences to AREA and VOLUME changes are observed during May and September. The strongest contribution from the downward long-wave heat flux to AREA changes occurs in September and to VOLUME changes in July–August. About 62 % of the AREA decrease simulated by the model can be explained by summing all contributions to the thermodynamic atmospheric forcing. The changing sea ice state (sensitivity) is found to enhance the decline and accounts for about one third of the explained reduction. For the VOLUME decrease, the explained fraction of the decrease is only about 37 %.  相似文献   

An improved fast level set method initialized with a combination of k-means clustering and Otsu thresholding for unsupervised change detection from SAR images     

Armin Moghimi  Safa Khazai  Ali Mohammadzadeh 《Arabian Journal of Geosciences》2017,10(13):293

Detection of changes in synthetic aperture radar (SAR) images is an important challenge due to the effects of speckle noise on these images. In recent years, appropriate methods for SAR-based-change detection have been developed based on the level set methods (LSM). These methods need to set parameters for defining a proper initial contour. Moreover, the gradient information is only employed in the total energy of these methods for segmentation of the difference image. In this study, a novel method has been proposed for unsupervised change detection of multitemporal SAR images based on the improved fast level set method (IFLSM) initialized with a combination of k-means and Otsu techniques. The proposed method utilizes the discrete wavelet transform (DWT) fusion strategy and edge enhancement to achieve a noise-resistant difference image from the mean-ratio and log-ratio images. Afterward, the generated binary change map (CM) by applying a combination of k-means and Otsu techniques on the difference image is used as the initial contour to achieve a final CM on difference image using the IFLSM. To check advantages of the proposed method, experiments are applied on two sets of multitemporal SAR images corresponding to artificial Chitgar Lake (under reconstruction) in Tehran (Iran) taken by TerraSAR-X satellite in 2011 and 2012, and corresponding to San Pablo and Briones reservoirs in California (USA) acquired by ERS-2 satellite in 2003 and 2004. Results of proposed method were compared with results of some well-known unsupervised change detection methods. Experimental results prove the sufficiency of the proposed method in unsupervised change detection in terms of accuracy, implementation time, and computational complexity.  相似文献