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11.
Harald Geiger Ian Barnes Karl H. Becker Birger Bohn Theo Brauers Birgit Donner Hans-Peter Dorn Manfred Elend Carlos M. Freitas Dinis Dirk Grossmann Heinz Hass Holger Hein Axel Hoffmann Lars Hoppe Frank Hülsemann Dieter Kley Björn Klotz Hans G. Libuda Tobias Maurer Djuro Mihelcic Geert K. Moortgat Romeo Olariu Peter Neeb Dirk Poppe Lars Ruppert Claudia G. Sauer Oleg Shestakov Holger Somnitz William R. Stockwell Lars P. Thüner Andreas Wahner Peter Wiesen Friedhelm Zabel Reinhard Zellner Cornelius Zetzsch 《Journal of Atmospheric Chemistry》2002,42(1):323-357
Within the German Tropospheric Research Programme (TFS) numerous kinetic and mechanistic studies on the tropospheric reaction/degradation of the following reactants were carried out: oxygenated VOC, aromatic VOC, biogenic VOC, short-lived intermediates, such as alkoxy and alkylperoxy radicals.At the conception of the projects these selected groups were classes of VOC or intermediates for which the atmospheric oxidation mechanisms were either poorly characterised or totally unknown. The motivation for these studies was the attainment of significant improvements in our understanding of the atmospheric chemical oxidation processes of these compounds, particularly with respect to their involvement in photooxidant formation in the troposphere. In the present paper the types of experimental investigations performed and the results obtained within the various projects are briefly summarised. The major achievements are highlighted and discussed in terms of their contribution to improving our understanding of the chemical processes controlling photosmog formation in the troposphere. 相似文献
12.
13.
The effect of horizontal resolution on simulation of very extreme US precipitation events in a global atmosphere model 总被引:1,自引:0,他引:1
We investigate the ability of a global atmospheric general circulation model (AGCM) to reproduce observed 20 year return values of the annual maximum daily precipitation totals over the continental United States as a function of horizontal resolution. We find that at the high resolutions enabled by contemporary supercomputers, the AGCM can produce values of comparable magnitude to high quality observations. However, at the resolutions typical of the coupled general circulation models used in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, the precipitation return values are severely underestimated. 相似文献
14.
Sushma Prasad Norbert Marwan Deniz Eroglu Bedartha Goswami Praveen K. Mishra Birgit Gaye A. Anoop N. Basavaiah Martina Stebich Arshid Jehangir 《地球表面变化过程与地形》2020,45(15):3842-3853
Extreme climate events have been identified both in meteorological and long-term proxy records from the Indian summer monsoon (ISM) realm. However, the potential of palaeoclimate data for understanding mechanisms triggering climate extremes over long time scales has not been fully exploited. A distinction between proxies indicating climate change, environment, and ecosystem shift is crucial for enabling a comparison with forcing mechanisms (e.g. El-Niño Southern Oscillation). In this study we decouple these factors using data analysis techniques [multiplex recurrence network (MRN) and principal component analyses (PCA)] on multiproxy data from two lakes located in different climate regions – Lonar Lake (ISM dominated) and the high-altitude Tso Moriri Lake (ISM and westerlies influenced). Our results indicate that (i) MRN analysis, an indicator of changing environmental conditions, is associated with droughts in regions with a single climate driver but provides ambiguous results in regions with multiple climate/environmental drivers; (ii) the lacustrine ecosystem was ‘less sensitive’ to forcings during the early Holocene wetter periods; (iii) archives in climate zones with a single climate driver were most sensitive to regime shifts; (iv) data analyses are successful in identifying the timing of onset of climate change, and distinguishing between extrinsic and intrinsic (lacustrine) regime shifts by comparison with forcing mechanisms. Our results enable development of conceptual models to explain links between forcings and regional climate change that can be tested in climate models to provide an improved understanding of the ISM dynamics and their impact on ecosystems. © 2020 John Wiley & Sons, Ltd. 相似文献
15.
Thomas M. Kreuzer Martina Wilde Birgit Terhorst Bodo Damm 《Earth Science Informatics》2017,10(4):507-515
Landslide research requires consistent and widespread data. Many countries within the European Union have national landslide inventories to fulfill these demands for their respective research. However, those inventories were usually not intended to provide the technical basis for automated process and risk analyses during their design phase. The ongoing development of Germany’s national landslide database offers the opportunity to do this differently. This paper introduces a landslide inventory system called WISL suitable for data handling as well as for novel automated process and risk analyses on a national scale. WISL is designated to form the technical infrastructure for a German national database. Its core consists of an open source relational database management system (PostgreSQL), standardized input and registration methods as well as integrated analyses modules, which avoid large data movement and allow for rapid risk analyses. We present proof-of-concept results of endangered infrastructure related to automated risk mappings based on topography and proximity of active landslides. The use of open source software and the application of a standardized input and data acquisition system for experts, coupled with custom analysis modules, constitutes a step toward automated risk maps by a mere ‘button-press’. Future developments for the inventory lie in the field of refining and inventing analysis modules and collecting data, for which WISL provides a firm technical base. 相似文献
16.
Levels and trends of persistent organic pollutants and trace elements in seabirds breeding in the vast Canadian Arctic have been monitored since 1975. Data from this monitoring have indicated both spatial and temporal variation across the region, attributable in part to differences in species' diets, differences in regional deposition patterns, and unidirectional trends in contaminants reaching this area from emissions in temperate and tropical areas to the south. Seabird tissues have served as effective biomonitors to examine this variation, and national and international collaboration in this monitoring effort has promoted valuable synthetic assessments of spatial and temporal patterns in Arctic contaminants. Here we review the history of the monitoring program, the critical role played by Environment Canada's National Wildlife Specimen Bank, and we summarize important spatial and temporal trends in various contaminants in Canadian Arctic seabirds. 相似文献
17.
Web-based Geographical Information Systems (GIS) are excellent tools within interdisciplinary and multi-national geoscience
projects to exchange and visualize project data. The web-based GIS presented in this paper was designed for the paleolimnological
project ‘High-resolution CONTINENTal paleoclimate record in Lake Baikal’ (CONTINENT) (Lake Baikal, Siberia, Russia) to allow
the interactive handling of spatial data. The GIS database combines project data (core positions, sample positions, thematic
maps) with auxiliary spatial data sets that were downloaded from freely available data sources on the world wide web. The
reliability of the external data was evaluated and suitable new spatial datasets were processed according to the scientific
questions of the project. GIS analysis of the data was used to assist studies on sediment provenance in Lake Baikal, or to
help answer questions such as whether the visualization of present-day vegetation distribution and pollen distribution supports
the conclusions derived from palynological analyses. The refined geodata are returned back to the scientific community by
using online data publication portals. Data were made citeable by assigning persistent identifiers (DOI) and were published
through the German National Library for Science and Technology (TIB Hannover, Hannover, Germany). 相似文献
18.
During the last decades, damages to houses caused by landslides have been consistently occurring in a residential area in Öschingen/Germany. The residential area is located in ductile Callovian clays (Jurassic). Furthermore, in the back slope of the research area, a large Pleistocene slide mass negatively influences the slope stability. Through an integrative approach, the maximum data available for the study area was compiled in order to create a susceptibility map for landslide hazard. Detailed geomorphological field survey provided a valuable base for the assessment of slope stability using Stability Index Mapping (SINMAP). In the framework of long-term studies, consolidated results concerning mass movements and climatic-driven Pleistocene slope evolution, as well as recent slope dynamics, could be gained. These outcomes are compared to the results provided by slope stability modelling with SINMAP. The calculations outline some parameters responsible for higher risks. In general, the interaction of topography, water balances and substrate at the Schönberger Kapf can be designated to cause instability in wide areas. Hydrological parameters are essential for destabilisation of slope and they cause at least temporally destabilisation along channel structures, which presumably are influenced by seasonally increased spring discharge and a reduction in the underground shear strength. The exceptional dimension of the rotational block in connection with the specific slope hydrologic conditions and the intensive anthropogenic impact in the rear slope of the building area Auchtert in Öschingen has to be termed very problematic on the basis of the studies carried out. 相似文献
19.
Torsten Sander Philipp Wehner 《International journal of geographical information science》2013,27(6):799-819
Today's map navigation software offers more and more functionality. For example, it cannot only route from a start to a destination address, but the user can also specify a number of via destinations that are to be visited along the route. What is not commonly found in the software is the handling of so-called stopover areas. Here the user specifies a sequence of geographic areas and wants the route to lead into or through each of these areas (but he does not actually care where exactly). A modification of the well-known A☆ algorithm that considers convex stopover areas is presented. Algorithmic variants and implementation issues are discussed. Example results on a real-world data set are presented for the case of axis parallel rectangular stopover areas. 相似文献
20.
The southern Yucatán (SY) has been recognized as a hotspot of biodiversity with great risk of deforestation. Land change analysis, based on classified Landsat TM and ETM?+?satellite imagery (1990, 2000 and 2006), was used to estimate the annual deforestation rates of 141 land management units of the SY, and spatial patterns of forest fragmentation around and within the Calakmul Biosphere Reserve (CBR), which comprises approximately one-third of the region. Results indicate a decrease in annual deforestation rates over 1990–2006, from 0.15% year?1 to 0.06% year?1, but with significant sub-regional variations in the quantity and rate of forest loss. Despite a decline in deforestation during this period, there was considerable fragmentation both inside and outside the CBR. While population pressures and the expansion of pasture have caused deforestation across the region, agricultural intensification, diversified income strategies and reserve conservation may have contributed to reduced forest loss during the study period. 相似文献