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  • 1
    UID:
    edochu_18452_21854
    Format: 1 Online-Ressource (11 Seiten)
    Content: We evaluated the effectiveness of different approaches to compensate for across-track brightness gradients within a hyperspectral image mosaic comprised of multiple flight lines in the San Francisco Bay Area. We calculated the spectral consistency of adjacent flight lines and conducted regression-based unmixing of woody- and non-woody vegetation fractions to assess the comparative benefits of the methods. Results showed that a class-wise empirical approach produced the most spectrally consistent, nearly seamless image mosaics and led to accurate vegetation fraction maps (mean absolute error = 12.6%). Overall, a class-wise empirical approach is recommended as a simple, flexible and transferable technique to compensate for brightness gradients over a global empirical approach, brightness normalization or continuum removal.
    Content: Peer Reviewed
    Note: This article was supported by the Open Access Publication Fund of Humboldt-Universität zu Berlin.
    In: Abingdon [u.a.] : Taylor & Francis, 2020, 11,1, Seiten 1-10
    Language: English
    URL: Volltext  (kostenfrei)
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  • 2
    UID:
    edochu_18452_24690
    Format: 1 Online-Ressource (12 Seiten)
    Content: Grassland plays an important role in German agriculture. The interplay of ecological processes in grasslands secures important ecosystem functions and, thus, ultimately contributes to essential ecosystem services. To sustain, e.g., the provision of fodder or the filter function of soils, agricultural management needs to adapt to site-specific grassland characteristics. Spatially explicit information derived from remote sensing data has been proven instrumental for achieving this. In this study, we analyze the potential of Sentinel-2 data for deriving grassland-relevant parameters. We compare two well-established methods to calculate the aboveground biomass and leaf area index (LAI), first using a random forest regression and second using the soil–leaf-canopy (SLC) radiative transfer model. Field data were recorded on a grassland area in Brandenburg in August 2019, and were used to train the empirical model and to validate both models. Results confirm that both methods are suitable for mapping the spatial distribution of LAI and for quantifying aboveground biomass. Uncertainties generally increased with higher biomass and LAI values in the empirical model and varied on average by a relative RMSE of 11% for modeling of dry biomass and a relative RMSE of 23% for LAI. Similar estimates were achieved using SLC with a relative RMSE of 30% for LAI retrieval, and a relative RMSE of 47% for the estimation of dry biomass. Resulting maps from both approaches showed comprehensible spatial patterns of LAI and dry biomass distributions. Despite variations in the value ranges of both maps, the average estimates and spatial patterns of LAI and dry biomass were very similar. Based on the results of the two compared modeling approaches and the comparison to the validation data, we conclude that the relationship between Sentinel-2 spectra and grassland-relevant variables can be quantified to map their spatial distributions from space. Future research needs to investigate how similar approaches perform across different grassland types, seasons and grassland management regimes.
    Content: Peer Reviewed
    In: Journal of photogrammetry, remote sensing and geoinformation science, Cham : Springer International Publishing, 88,2020, Seiten 379-390
    Language: English
    URL: Volltext  (kostenfrei)
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  • 3
    UID:
    edochu_18452_7166
    Format: 1 Online-Ressource (9 Seiten)
    Content: Der Bologna-Prozess ist in seinen strukturellen Auswirkungen eng verbunden mit der Nutzung digitaler Technologien. Die damit verbundenen Fragen werden unter dem Stichwort E-Bologna diskutiert. Zwei Themen stehen dabei im Vordergrund: Wie müssen die vorhandenen Systeme an Hochschulen aus einer organisatorischen und administrativen Perspektive integriert und erweitert werden und welche Möglichkeiten bieten digitale Technologien in der Lehre, die Förderung von Mobilität, lebenslangem Lernen und Aufbau von Schlüsselkompetenzen zu unterstützen? Der Beitrag zeigt praxisnahe Beispiele, wie an den Instituten der Humboldt-Universität flexibel mit den neuen Herausforderungen umgegangen wird. Die präsentierten Lösungen sind eng an konkreten Herausforderungen entwickelt worden und haben nicht den Anspruch eine umfassende Lösung zu erarbeiten. Sie sind vielmehr strikt pragmatisch angelegt und damit alltagstauglich im fachlichen Kontext. Der Beitrag will Anregungen und Beispiele geben, wie die mit Bologna verbundenen Herausforderungen mit Hilfe digitaler Technologien gemeistert werden.
    In: Facetten von Bologna, ,2007,29, Seiten 3-11
    Language: German
    URL: Volltext  (kostenfrei)
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  • 4
    UID:
    edochu_18452_18835
    Format: 1 Online-Ressource (14 Seiten)
    ISSN: 1471-2458 , 1471-2458
    Content: BACKGROUND: Urban health is of global concern because the majority of the world's population lives in urban areas. Although mental health problems (e.g. depression) in developing countries are highly prevalent, such issues are not yet adequately addressed in the rapidly urbanising megacities of these countries, where a growing number of residents live in slums. Little is known about the spectrum of mental well-being in urban slums and only poor knowledge exists on health promotive socio-physical environments in these areas. Using a geo-epidemiological approach, the present study identified factors that contribute to the mental well-being in the slums of Dhaka, which currently accommodates an estimated population of more than 14 million, including 3.4 million slum dwellers. METHODS: The baseline data of a cohort study conducted in early 2009 in nine slums of Dhaka were used. Data were collected from 1,938 adults (\textgreater/= 15 years). All respondents were geographically marked based on their households using global positioning systems (GPS). Very high-resolution land cover information was processed in a Geographic Information System (GIS) to obtain additional exposure information. We used a factor analysis to reduce the socio-physical explanatory variables to a fewer set of uncorrelated linear combinations of variables. We then regressed these factors on the WHO-5 Well-being Index that was used as a proxy for self-rated mental well-being. RESULTS: Mental well-being was significantly associated with various factors such as selected features of the natural environment, flood risk, sanitation, housing quality, sufficiency and durability. We further identified associations with population density, job satisfaction, and income generation while controlling for individual factors such as age, gender, and diseases. CONCLUSIONS: Factors determining mental well-being were related to the socio-physical environment and individual level characteristics. Given that mental well-being is associated with physiological well-being, our study may provide crucial information for developing better health care and disease prevention programmes in slums of Dhaka and other comparable settings.
    Content: Peer Reviewed
    Note: Die Zweitveröffentlichung der Publikation wurde durch Studierende des Projektseminars "Open Access Publizieren an der HU" im Sommersemester 2017 betreut. Nachgenutzt gemäß den CC-Bestimmungen des Lizenzgebers bzw. einer im Dokument selbst enthaltenen CC-Lizenz.
    In: BMC Public Health, : BioMed Central, 12,2012, Seiten 177-191, 1471-2458
    Language: English
    URL: Volltext  (kostenfrei)
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  • 5
    UID:
    kobvindex_GFZ1778012027
    Format: xxiv, 134 Seiten , Illustrationen, Diagramme, Karten
    Content: Permafrost is warming globally, which leads to widespread permafrost thaw and impacts the surrounding landscapes, ecosystems and infrastructure. Especially ice-rich permafrost is vulnerable to rapid and abrupt thaw, resulting from the melting of excess ground ice. Local remote sensing studies have detected increasing rates of abrupt permafrost disturbances, such as thermokarst lake change and drainage, coastal erosion and RTS in the last two decades. All of which indicate an acceleration of permafrost degradation. In particular retrogressive thaw slumps (RTS) are abrupt disturbances that expand by up to several meters each year and impact local and regional topographic gradients, hydrological pathways, sediment and nutrient mobilisation into aquatic systems, and increased permafrost carbon mobilisation. The feedback between abrupt permafrost thaw and the carbon cycle is a crucial component of the Earth system and a relevant driver in global climate models. However, an assessment of RTS at high temporal resolution to determine the ...
    Note: kumulative Dissertation , Dissertation, Universität Potsdam, 2021 , Table of Contents Abstract Zusammenfassung List of Figures List of Tables Abbreviations 1 Introduction 1.1 Scientific background and motivation 1.1.1 Permafrost and climate change 1.1.2 Permafrost thaw and disturbances 1.1.3 Abrupt permafrost disturbances 1.1.4 Remote sensing 1.1.5 Remote sensing of permafrost disturbances 1.2 Aims and objectives 1.3 Study area 1.4 General data and methods 1.4.1 Landsat and Sentinel-2 1.4.2 Google Earth Engine 1.5 Thesis structure 1.6 Overview of publications and authors’ contribution 1.6.1 Chapter 2 - Comparing Spectral Characteristics of Landsat-8 and Sentinel-2 Same-Day Data for Arctic-Boreal Regions 1.6.2 Chapter 3 - Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions 1.6.3 Chapter 4 - Remote Sensing Annual Dynamics of Rapid Permafrost Thaw Disturbances with LandTrendr 2 Comparing Spectral Characteristics of Landsat-8 and Sentinel-2 Same-Day Data for Arctic-Boreal Regions 2.1 Abstract 2.2 Introduction 2.3 Materials and Methods 2.3.1 Study Sites 2.3.2 Data 2.3.3 Data Processing 2.3.3.1 Filtering Image Collections 2.3.3.2 Creating L8, S2, and Site Masks 2.3.3.3 Preparing Sentinel-2 Surface Reflectance Images in SNAP 2.3.3.4 Applying Site Masks 2.3.4 Spectral Band Comparison and Adjustment 2.4 Results 2.4.1 Spectral Band Comparison 2.4.2 Spectral Band Adjustment 2.4.3 ES and HLS Spectral Band Adjustment 2.5 Discussion 2.6 Conclusions 2.7 Acknowledgements 2.8 Appendix Chapter 2 3 Mosaicking Landsat and Sentinel-2 Data to Enhance LandTrendr Time Series Analysis in Northern High Latitude Permafrost Regions 3.1 Abstract 3.2 Introduction 3.3 Materials and Methods 3.3.1 Study Sites 3.3.2 Data 3.3.3 Data Processing and Mosaicking Workflow 3.3.4 Data Availability Assessment 3.3.5 Mosaic Coverage and Quality Assessment 3.4 Results 3.4.1 Data Availability Assessment 3.4.2 Mosaic Coverage and Quality Assessment 3.5 Discussion 3.6 Conclusions 4 Remote Sensing Annual Dynamics of Rapid Permafrost Thaw Disturbances with LandTrendr 4.1 Abstract 4.2 Introduction 4.3 Study Area and Methods 4.3.1 Study area 4.3.2 General workflow and ground truth data 4.3.3 Data and LandTrendr 4.3.4 Index selection 4.3.5 Temporal Segmentation 4.3.6 Spectral Filtering 4.3.7 Spatial masking and filtering 4.3.8 Machine-learning object filter 4.4 Results 4.4.1 Focus sites 4.4.2 North Siberia 4.5 Discussion 4.5.1 Mapping of RTS 4.5.2 Spatio-temporal variability of RTS dynamics 4.5.3 LT-LS2 capabilities and limitations 4.6 Conclusion 4.7 Appendix 5 Synthesis and Discussion 5.1 Google Earth Engine 5.2 Landsat and Sentinel-2 5.3 Image mosaics and disturbance detection algorithm 5.4 Mapping RTS and their annual temporal dynamics 5.5 Limitations and technical considerations 5.6 Key findings 5.7 Outlook References Acknowledgements
    Language: English
    Keywords: Hochschulschrift
    Author information: Große, Guido 1976-
    Author information: Hostert, Patrick 1967-
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  • 6
    UID:
    edochu_18452_21116
    Format: 1 Online-Ressource (24 Seiten)
    Content: The attribution of forest disturbances to disturbance agents is a critical challenge for remote sensing-based forest monitoring, promising important insights into drivers and impacts of forest disturbances. Previous studies have used spectral-temporal metrics derived from annual Landsat time series to identify disturbance agents. Here, we extend this approach to new predictors derived from intra-annual time series and test it at three sites in Central Europe, including managed and protected forests. The two newly tested predictors are: (1) intra-annual timing of disturbance events and (2) temporal proximity to windstorms based on prior knowledge. We estimated the intra-annual timing of disturbances using a breakpoint detection algorithm and all available Landsat observations between 1984 and 2016. Using spectral, temporal, and topography-related metrics, we then mapped four disturbance classes: windthrow, cleared windthrow, bark beetles, and other harvest. Disturbance agents were identified with overall accuracies of 76–86%. Temporal proximity to storm events was among the most important predictors, while intra-annual timing itself was less important. Moreover, elevation information was very effective for discriminating disturbance agents. Our results demonstrate the potential of incorporating dense, intra-annual Landsat time series information and prior knowledge of disturbance events for monitoring forest ecosystem change at the disturbance agent level.
    Content: Peer Reviewed
    In: Basel : MDPI, 8,7, Seiten 251/1-251/24
    Language: English
    URL: Volltext  (kostenfrei)
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  • 7
    UID:
    edochu_18452_24261
    Format: 1 Online-Ressource (10 Seiten)
    Content: In agricultural grassland, high herbage utilisation efficiency (HEFF), which is the proportion of gross live-green herbage production that is utilised before entering senescence, is ensured by frequent defoliation. The decision upon which defoliation frequency to apply depends on the farming intensity. Assuming a reduced total herbage accumulation near trees in silvopastoral systems, frequent defoliations with high HEFF become less worthwhile—at least in specific spatial configurations. This makes an extensive management near trees an interesting option because it promotes other grassland-related ecosystem services such as biodiversity. The present study first analysed the interaction between defoliation frequency and position to trees on the total, dead and live herbage accumulation and the HEFF at two silvopastoral sites with short-rotation coppices in Germany. In addition, the total grassland–tree interface in Germany was assessed from land use and land cover maps of Germany based on satellite data to approximate the potential of grassland extensification near trees. The total herbage accumulation near trees declined by up to 41% but the HEFF was not affected by the position. Consequently, any intensification is not paid-off by adequate productivity and herbage quality in terms of HEFF and tree-related losses in herbage accumulation are expected up to a distance of 4.5–6 m. Applying a 4.5 m border on satellite data, we found that up to 4.4% (approximately 2200 km2) of the total grassland area in Germany is at a tree interface and potentially suitable for extensification. These findings indicate substantial potential for biodiversity conservation in grasslands with low trade-off for high-quality yield.
    Content: Peer Reviewed
    In: Oxford : Wiley-Blackwell, 179,1, Seiten 75-84
    Language: English
    URL: Volltext  (kostenfrei)
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  • 8
    UID:
    edochu_18452_25568
    Format: 1 Online-Ressource (10 Seiten)
    Content: Global agricultural production will likely need to increase in the future due to population growth, changing diets, and the rising importance of bioenergy. Intensifying already existing cropland is often considered more sustainable than converting more natural areas. Unfortunately, our understanding of cropping patterns and intensity is weak, especially at broad geographic scales. We characterized and mapped cropping systems in Europe, a region containing diverse cropping systems, using four indicators: (a) cropping frequency (number of cropped years), (b) multi-cropping (number of harvests per year), (c) fallow cycles, and (d) crop duration ratio (actual time under crops) based on the MODIS Normalized Difference Vegetation Index (NDVI) time series from 2000 to 2012. Second, we used these cropping indicators and self-organizing maps to identify typical cropping systems. The resulting six clusters correspond well with other indicators of agricultural intensity (e.g., nitrogen input, yields) and reveal substantial differences in cropping intensity across Europe. Cropping intensity was highest in Germany, Poland, and the eastern European Black Earth regions, characterized by high cropping frequency, multi-cropping and a high crop duration ratio. Contrarily, we found lowest cropping intensity in eastern Europe outside the Black Earth region, characterized by longer fallow cycles. Our approach highlights how satellite image time series can help to characterize spatial patterns in cropping intensity—information that is rarely surveyed on the ground and commonly not included in agricultural statistics: our clustering approach also shows a way forward to reduce complexity when measuring multiple indicators. The four cropping indicators we used could become part of continental-scale agricultural monitoring in order to identify target regions for sustainable intensification, where trade-offs between intensification and the environmental should be explored.
    Content: Peer Reviewed
    In: Bristol : IOP Publ., 11,2
    Language: English
    URL: Volltext  (kostenfrei)
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  • 9
    UID:
    edochu_18452_26903
    Format: 1 Online-Ressource (15 Seiten)
    Content: Global societal material stock in buildings and infrastructure have accumulated rapidly within the last decades, along with population growth. Recently, an approach for nation-wide mapping of material stock at 10 m spatial resolution, using freely available and globally consistent Earth Observation (EO) imagery, has been introduced as an alternative to cost-intensive cadastral data or broad-scale but thematically limited nighttime light-based mapping. This study assessed the potential of EO data archives to create spatially explicit time series data of material stock dynamics and their relation to population in Germany, at a spatial resolution of 30 m. We used Landsat imagery with a change-aftereffect-trend analysis to derive yearly masks of land surface change from 1985 onward. Those served as an input to an annual reverse calculation of six material stock types and building volume-based annual gridded population, based on maps for 2018. Material stocks and population in Germany grew by 13% and 4%, respectively, showing highly variable spatial patterns. We found a minimum building stock of ca. 180 t/cap across all municipalities and growth processes characterized by sprawl. A rapid growth of stocks per capita occurred in East Germany after the reunification in 1990, with increased building activity but population decline. Possible over- or underestimations of stock growth cannot be ruled out due to methodological assumptions, requiring further research.
    Content: Peer Reviewed
    In: Oxford [u.a.] : Wiley-Blackwell, 27,1, Seiten 110-124
    Language: English
    URL: Volltext  (kostenfrei)
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  • 10
    UID:
    edochu_18452_19098
    Format: 1 Online-Ressource (10 Seiten)
    ISSN: 1877-3435 , 1877-3435
    Content: Future increases in land-based production will need to focus more on sustainably intensifying existing production systems. Unfortunately, our understanding of the global patterns of land use intensity is weak, partly because land use intensity is a complex, multidimensional term, and partly because we lack appropriate datasets to assess land use intensity across broad geographic extents. Here, we review the state of the art regarding approaches for mapping land use intensity and provide a comprehensive overview of available global-scale datasets on land use intensity. We also outline major challenges and opportunities for mappinglanduseintensityfor cropland, grazing, and forestry systems, and identify key issues for future research.
    Content: Peer Reviewed
    Note: Die Zweitveröffentlichung der Publikation wurde durch Studierende des Projektseminars "Open Access Publizieren an der HU" im Sommersemester 2017 betreut. Nachgenutzt gemäß den CC-Bestimmungen des Lizenzgebers bzw. einer im Dokument selbst enthaltenen CC-Lizenz.
    In: : Elsevier, 5,5, Seiten 484-493, 1877-3435
    Language: English
    URL: Volltext  (kostenfrei)
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