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  • Other Sources  (21)
  • English  (21)
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  • 2010-2014  (21)
  • 1
    Publication Date: 2023-07-18
    Language: English
    Type: info:eu-repo/semantics/article
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  • 2
    Publication Date: 2023-07-18
    Description: In this study the sensitivity of the model performance of the chemistry transport model (CTM) LOTOS-EUROS to the description of the temporal variability of emissions was investigated. Currently the temporal release of anthropogenic emissions is described by European average diurnal, weekly and seasonal time profiles per sector. These default time profiles largely neglect the variation of emission strength with activity patterns, region, species, emission process and meteorology. The three sources dealt with in this study are combustion in energy and transformation industries (SNAP1), nonindustrial combustion (SNAP2) and road transport (SNAP7). First of all, the impact of neglecting the temporal emission profiles for these SNAP categories on simulated concentrations was explored. In a second step, we constructed more detailed emission time profiles for the three categories and quantified their impact on the model performance both separately as well as combined. The performance in comparison to observations for Germany was quantified for the pollutants NO2, SO2 and PM10 and compared to a simulation using the default LOTOS-EUROS emission time profiles. The LOTOS-EUROS simulations were performed for the year 2006 with a temporal resolution of 1 h and a horizontal resolution of approximately 25 × 25km2. In general the largest impact on the model performance was found when neglecting the default time profiles for the three categories. The daily average correlation coefficient for instance decreased by 0.04 (NO2), 0.11 (SO2) and 0.01 (PM10) at German urban background stations compared to the default simulation. A systematic increase in the correlation coefficient is found when using the new time profiles. The size of the increase depends on the source category, component and station. Using national profiles for road transport showed important improvements in the explained variability over the weekdays as well as the diurnal cycle for NO2. The largest impact of the SNAP1 and 2 profiles were found for SO2. When using all new time profiles simultaneously in one simulation, the daily average correlation coefficient increased by 0.05 (NO2), 0.07 (SO2) and 0.03 (PM10) at urban background stations in Germany. This exercise showed that to improve the performance of a CTM, a better representation of the distribution of anthropogenic emission in time is recommendable. This can be done by developing a dynamical emission model that takes into account regional specific factors and meteorology.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 3
    Publication Date: 2021-03-29
    Description: research
    Keywords: 560 ; VV 000 ; Paläontologie
    Language: English
    Type: article , publishedVersion
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  • 4
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    Geozon Science Media
    Publication Date: 2021-03-29
    Description: Es wird immer schwieriger, vergleichende Studien über die zahlreichen Pollendiagramme eines Interglazials innerhalb Nordwesteuropas oder aber verschiedener Interglaziale dieses Raumes zu machen, und zwar wegen der Mannigfaltigkeit der Zonierungssysteme, die die einzelnen Autoren anwenden. Dennoch haben aber Iversen (1958) und Andersen (1966) gezeigt, daß in jedem der bisher untersuchten Interglaziale ähnliche Zyklen der Vegetationsentwicklung und der Bodenbildung abgelaufen sind. Die Verfasser legen dar, daß in jeder Interglazialzeit 4 Perioden der Vegetationsentwicklung festgestellt werden können und daß diese als natürliche biostratigraphische Zonen angesehen werden können, basierend auf dem Charakter der Pollengemeinschaften. Diese Perioden sind: Zone I, die Pre-temperate Zone, Betula und Pinus dominieren; Zone II, die Early-temperate Zone, Vorherrschaft der Bäume des Eichenmischwaldes; Zone III, die Late-temperate Zone, in zunehmendem Maße beherrscht durch spät einwandernde wärmeliebende Bäume, wie Carpinus und Abies; Zone IV, die Post-temperate Zone, wiederum beherrscht durch boreale Bäume, wie Pinus und Betula. Diese Zonierung kann für fast alle interglazialen Pollendiagramme Nordwesteuropas verwandt werden. Geringe Veränderungen der Vegetation, und zwar regional, lokal oder seral, können als Unterzonen beschrieben werden, ohne die Hauptzüge und den Zweck dieses Zonierungssystems zu stören.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; subdivision ; zonation ; pollen ; interglacial ; vegetational development ; biostratigraphy ; betula ; pinus ; carpinus ; abies
    Language: English
    Type: article , publishedVersion
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  • 5
    Publication Date: 2021-03-29
    Description: Ein rezenter Boden und zwei begrabene Paläoböden, Einheiten II-III-IV (oberer) und IV (unterer)-V, liefern wichtige Informationen über Paläoklima und Abflußverhältnisse in den Virunga-Bergen von trockeneren zu feuchteren paläoklimatischen Phasen des Spätglazials bis zu mittleren postglazialen Zeiten. Zusammenfassend betrachtet, weist die stratigraphische Abfolge zunächst auf eine Verwitterungsperiode des Festgesteins hin, der eine Phase folgt, in der tuffige Schichten abgelagert wurden. Die Zeit war von einer Verwitterung unter trockeneren und vielleicht kälteren Bedingungen begleitet. Später, während des letzten Glazials, kam es bei verstärkter Aktivität der Flüsse zur Sedimentation von Schwemmlandablagerungen, die von einer dünnen Tuff-Schicht überdeckt wurden. Diese Sedimente sind intensiver verwittert als die liegenden Schichten. Der rezente Boden zeigt eine vergleichsweise geringe Verwitterung mobiler Elemente, was darauf hindeutet, daß die Klimaverhältnisse im späten Mittel-Holozän und Spät-Holozän etwas trockener und vielleicht kühler waren als im Früh-Holozän. Die Geochemie der drei Böden zeigt eine bedeutende Abnahme von Na, Ca und K im mittleren Paläoböden im Vergleich zum älteren Paläoböden und zu den rezenten Böden. Eisen als ein wichtiger Indikator für das Paläoklima deutet daraufhin, daß die mittleren Einheiten II und III des oberen Paläobodens unter feuchteren Klimabedingungen als heute entstanden sind. Die Radiokarbon-Datierungen des mittleren Paläobodens zeigen, daß dieser Boden einer sub-aerischen Verwitterung vom Kalambo-Interstadial (» 25000 Jahre vor heute) bis zum Mittel-Holozän ausgesetzt war. Die gesamte Verwitterung im mittleren Abschnitt ist zu weit fortgeschritten und während des Holozäns entstanden. Die relativ hohe Konzentration von Th in den anstehenden Festgesteinen, Tuffen, Schwemmlandsedimenten und Hangrutschmassen zeigt, daß Th die Quelle der Radioaktivität ist, von der andere Autoren aus den Virunga-Bergen berichten.
    Description: research
    Keywords: 551.7 ; VAR 000 ; Glazialgeologie ; stratigraphy ; geochemistry ; virunga mountains ; northwestern rwanda ; quaternary ; africa ; palaeomagnetic research
    Language: English
    Type: article , publishedVersion
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  • 6
    Publication Date: 2021-03-29
    Description: research
    Keywords: 560 ; VU 000 ; Geobiologie
    Language: English
    Type: anthologyArticle , publishedVersion
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  • 7
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    Potsdam-Institut für Klimafolgenforschung
    In:  PIK Report
    Publication Date: 2022-03-21
    Description: In coupled human-environment systems where well established and proven general theories are often lacking cluster analysis provides the possibility to discover regularities – a first step in empirically based theory building. The aim of this report is to share the experiences and knowledge on cluster analysis we gained in several applications in this realm helping to avoid typical problems and pitfalls. In our description of issues and methods we will highlight well-known main-stream methods as well as promising new developments, referring to pertinent literature for further information, thus offering also some potential new insights for the more experienced. The following aspects are discussed in detail: data-selection and pre-treatment, selection of a distance measure in the data space, selection of clustering method, performing clustering (parameterizing the algorithm(s), determining the number of clusters etc.) and the interpretation and evaluation of results. We link our description – as far as tools for performing the analysis are concerned - to the R software environment and its associated cluster analysis packages. We have used this public domain software, together with own tailor-made extensions, documented in the appendix.
    Language: English
    Type: info:eu-repo/semantics/report
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  • 8
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    Potsdam-Institut für Klimafolgenforschung
    In:  PIK Report
    Publication Date: 2022-03-21
    Description: A methodology to assess future development in patterns of vulnerability is presented which can support the assessment of global policies with regard to their impacts on specific vulnerabilities on the regional or local scale. Patterns of vulnerability, formalized by vulnerability profiles (e.g. for the livelihoods of dryland smallholder farmers) were investigated under different consistent indicator scenarios reflecting different global policies. After unfolding several principal possibilities to do such an analysis of temporal change in vulnerability patterns we could conclude that the concept of “Clusters of Change” (CoCs) is the most straight forward and promising approach. The main arguments are that each interpretation has necessarily to consider both, the starting situation and it’s change over time (”poor and heavily improving”, ”rich and stagnating” etc.). This implies that we are looking for patterns which represent typical combinations of present states AND expected future changes. An application of the CoC-concept to the drylands vulnerability patterns considering the indicator set for the present situation and the same indicator set for 2050 under a baseline scenario was performed as a test. Comparison of the present vulnerability cluster partition with the spatial distribution of the CoCs revealed that most of these clusters are separated into an improving and a deteriorating part which shows where winners and losers of the baseline scenario are – an interesting result which illustrates the appropriateness of the CoC – method. To explore the potential of CoCs for the dryland vulnerability we applied the method to two different sets of scenarios until 2050: a baseline vs. Climate policy scenario (OECD, 2012) and a ”policy first” scenario vs. ”security first” scenario (UNEP, 2007). The first one serves as an example for a policy assessment while the second compares the vulnerability consequences of two scenarios based on different story-lines of further global development. The main conclusion to be drawn from these calculations is that the CoCs are rather insensitive with regard to the small differences between the scenarios. Regarding the first set of scenarios the relatively short time horizon of relevant influences of climate policies on climate change impacts and several indicators which are not influenced at all generate only a very small difference. The only significant change in the resulting vulnerability profiles was in the values of change in water scarcity: it was lower for all profiles in the climate policy case. The second set of scenarios is not directly related to policy decisions but to different global story-lines which deviate stronger. This resulted in an increasing cluster number from 4 (policy first) to 5 (security first) clusters, about 20% of the pixels changing cluster membership, 3 clusters showing the same spatial extent for both scenarios but the 4th cluster (“policy first”) “losing” India which generates a separate cluster in the “security first” scenario. This allows for the interpretation that a further development according to the “security first”-storyline compared to the “policy first”-storyline would make a difference particularly for India. Closer inspection of the respective profile shows a qualitatively different situation indicating increased vulnerability compared to the “policy first” scenario where India shares one cluster with e.g., Northern Africa.
    Language: English
    Type: info:eu-repo/semantics/report
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  • 9
    Publication Date: 2023-07-18
    Language: English
    Type: info:eu-repo/semantics/article
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  • 10
    Publication Date: 2023-07-18
    Description: Hydrothermal carbonization (HTC) is an aqueous-phase route to produce carbon materials using biomass or biomass-derived precursors. In this paper, a comprehensive physicochemical and textural characterization of HTC materials obtained using four different precursors, namely, xylose, glucose, sucrose, and starch, is presented. The development of porosity in the prepared HTC materials as a function of thermal treatment (under an inert atmosphere) was specifically monitored using N2 and CO2 sorption analysis. The events taking place during the thermal treatment process were studied by a combined thermogravimetric/infrared (TGA-IR) measurement. Interestingly, these inexpensive biomass-derived carbon materials show good selectivity for CO2 adsorption over N2 (CO2/N2 selectivity of 20 at 273 K, 1 bar and 1:1 gas composition). Furthermore, the elemental composition, morphologies, degree of structural order, surface charge, and functional groups are also investigated.
    Language: English
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