The Experts below are selected from a list of 43926 Experts worldwide ranked by ideXlab platform

Kyung Pak - One of the best experts on this subject based on the ideXlab platform.

  • Surface clutter due to antenna sidelobes for spaceborne Atmospheric radar
    IEEE Transactions on Geoscience and Remote Sensing, 2001
    Co-Authors: S.l. Durden, Ralph Girard, Kyung Pak
    Abstract:

    A spaceborne radar for Atmospheric Observation must be able to detect Atmospheric backscatter in the presence of clutter from the surface, due to antenna sidelobes. Such clutter can come from the same pulse as that observing the atmosphere if the radar antenna is pointed off-nadir. However pulses both prior and subsequent to the pulse observing the atmosphere can also contribute to clutter, and surface clutter can be a problem even for nadir-looking radars. Here, the problem is analyzed by deriving a method for computing clutter which includes effects of all contributing transmit pulses, Doppler shifting, finite receiver bandwidth, and curved Earth's surface. The results are applied to analysis of existing radars and design of future radar systems.

S.l. Durden - One of the best experts on this subject based on the ideXlab platform.

  • Surface clutter due to antenna sidelobes for spaceborne Atmospheric radar
    IEEE Transactions on Geoscience and Remote Sensing, 2001
    Co-Authors: S.l. Durden, Ralph Girard, Kyung Pak
    Abstract:

    A spaceborne radar for Atmospheric Observation must be able to detect Atmospheric backscatter in the presence of clutter from the surface, due to antenna sidelobes. Such clutter can come from the same pulse as that observing the atmosphere if the radar antenna is pointed off-nadir. However pulses both prior and subsequent to the pulse observing the atmosphere can also contribute to clutter, and surface clutter can be a problem even for nadir-looking radars. Here, the problem is analyzed by deriving a method for computing clutter which includes effects of all contributing transmit pulses, Doppler shifting, finite receiver bandwidth, and curved Earth's surface. The results are applied to analysis of existing radars and design of future radar systems.

  • Surface clutter due to antenna sidelobes for spaceborne Atmospheric radar
    IGARSS 2000. IEEE 2000 International Geoscience and Remote Sensing Symposium. Taking the Pulse of the Planet: The Role of Remote Sensing in Managing t, 1
    Co-Authors: S.l. Durden
    Abstract:

    A spaceborne radar for Atmospheric Observation must be able to detect Atmospheric backscatter in the presence of clutter due to antenna sidelobes. Here, we analyze the problem in detail, deriving a method for computing clutter which includes the effects of all contributing transmit pulses, Doppler shifting, finite receiver bandwidth, and the curved Earth's surface. The results are applied to analysis of existing radars and design of future radar systems.

Alfred Wiedensohler - One of the best experts on this subject based on the ideXlab platform.

  • A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
    Atmospheric Measurement Techniques, 2020
    Co-Authors: Paolo Laj, Clémence Rose, Alfred Wiedensohler, Alessandro Bigi, Elisabeth Andrews, Cathrine Lund Myhre, Martine Coen, Yong Lin, Michael Schulz, John Ogren
    Abstract:

    Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short Atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through Observations involving, in particular, the in situ near-surface segment of the Atmospheric Observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN).
    Earth System Science Data, 2016
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, Jia Sun, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained ( doi:10.5072/guan ).

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)
    2015
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau, J. Cyrys
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).

G. Löschau - One of the best experts on this subject based on the ideXlab platform.

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN).
    Earth System Science Data, 2016
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, Jia Sun, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained ( doi:10.5072/guan ).

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)
    2015
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau, J. Cyrys
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).

Wolfram Birmili - One of the best experts on this subject based on the ideXlab platform.

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN).
    Earth System Science Data, 2016
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, Jia Sun, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained ( doi:10.5072/guan ).

  • Significant increase of aerosol number concentrations in air masses crossing a densely trafficked sea area
    Oceanologia, 2016
    Co-Authors: Simonas Kecorius, Wolfram Birmili, Niku Kivekäs, Adam Kristensson, Thomas Tuch, David S. Covert, Heikki Lihavainen, Antti-pekka Hyvärinen, Johan Martinsson, Moa K. Sporre
    Abstract:

    In this study, we evaluated 10 months data (September 2009 to June 2010) of Atmospheric aerosol particle number size distribution at three Atmospheric Observation stations along the Baltic Sea coast: Vavihill (upwind, Sweden), Uto (upwind, Finland), and Preila (downwind, Lithuania). Differences in aerosol particle number size distributions between the upwind and downwind stations during situations of connected Atmospheric flow, when the air passed each station, were used to assess the contribution of ship emissions to the aerosol number concentration (diameter interval 50-400 nm) in the Lithuanian background coastal environment. A clear increase in particle number concentration could be noticed, by a factor of 1.9 from Uto to Preila (the average total number concentration at Uto was 791 cm(-3)), and by a factor of 1.6 from Vavihill to Preila (the average total number concentration at Vavihill was 998 cm(-3)). The simultaneous measurements of absorption Angstrom exponents close to unity at Preila supported our conclusion that ship emissions in the Baltic Sea contributed to the increase in particle number concentration at Preila. (C) 2015 Institute of Oceanology of the Polish Academy of Sciences. (Less)

  • Long-term Observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)
    2015
    Co-Authors: Wolfram Birmili, Kay Weinhold, Fabian Rasch, A. Sonntag, M. Merkel, Alfred Wiedensohler, Susanne Bastian, A. Schladitz, G. Löschau, J. Cyrys
    Abstract:

    Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative Atmospheric Observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both, climate and health related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at seventeen Observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).