The Experts below are selected from a list of 102 Experts worldwide ranked by ideXlab platform

Jens Wickert - One of the best experts on this subject based on the ideXlab platform.

  • On the determination of gravity wave momentum flux from GPS radio occultation data
    Atmospheric Measurement Techniques, 2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. Global Positioning System (GPS) radio occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received by low Earth-orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions, offering the possibility of global monitoring of the vertical temperature structure and atmospheric wave parameters. The six-satellite constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. Here, a method for the determination of the real horizontal wavelength from three vertical profiles is applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep), and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • A new approach to global gravity wave momentum flux determination from GPS radio occultation data
    2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. GPS Radio Occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions offering the possibility for global monitoring of the vertical temperature structure and atmospheric wave parameters. The six satellites constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. The horizontal wavenumber is derived by the ratio of the phase shift and the spatial distance between adjacent temperature fluctuation profiles at a given altitude, following the method by Ern et al. (2004). A new method for the determination of the real horizontal wavelength from triads of vertical profiles is presented and applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep) and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • Global gravity wave activity in the tropopause region from CHAMP radio occultation data
    Geophysical Research Letters, 2008
    Co-Authors: Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    [1] We discuss the global gravity wave (GW) activity expressed by the Specific Potential Energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean Potential Energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered.

Torsten Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • On the determination of gravity wave momentum flux from GPS radio occultation data
    Atmospheric Measurement Techniques, 2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. Global Positioning System (GPS) radio occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received by low Earth-orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions, offering the possibility of global monitoring of the vertical temperature structure and atmospheric wave parameters. The six-satellite constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. Here, a method for the determination of the real horizontal wavelength from three vertical profiles is applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep), and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • A new approach to global gravity wave momentum flux determination from GPS radio occultation data
    2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. GPS Radio Occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions offering the possibility for global monitoring of the vertical temperature structure and atmospheric wave parameters. The six satellites constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. The horizontal wavenumber is derived by the ratio of the phase shift and the spatial distance between adjacent temperature fluctuation profiles at a given altitude, following the method by Ern et al. (2004). A new method for the determination of the real horizontal wavelength from triads of vertical profiles is presented and applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep) and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • Global gravity wave activity in the tropopause region from CHAMP radio occultation data
    Geophysical Research Letters, 2008
    Co-Authors: Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    [1] We discuss the global gravity wave (GW) activity expressed by the Specific Potential Energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean Potential Energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered.

A. De La Torre - One of the best experts on this subject based on the ideXlab platform.

  • On the determination of gravity wave momentum flux from GPS radio occultation data
    Atmospheric Measurement Techniques, 2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. Global Positioning System (GPS) radio occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received by low Earth-orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions, offering the possibility of global monitoring of the vertical temperature structure and atmospheric wave parameters. The six-satellite constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. Here, a method for the determination of the real horizontal wavelength from three vertical profiles is applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep), and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • A new approach to global gravity wave momentum flux determination from GPS radio occultation data
    2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. GPS Radio Occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions offering the possibility for global monitoring of the vertical temperature structure and atmospheric wave parameters. The six satellites constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. The horizontal wavenumber is derived by the ratio of the phase shift and the spatial distance between adjacent temperature fluctuation profiles at a given altitude, following the method by Ern et al. (2004). A new method for the determination of the real horizontal wavelength from triads of vertical profiles is presented and applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep) and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • Global gravity wave activity in the tropopause region from CHAMP radio occultation data
    Geophysical Research Letters, 2008
    Co-Authors: Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    [1] We discuss the global gravity wave (GW) activity expressed by the Specific Potential Energy in the altitude range from 5 km below to 10 km above the tropopause, derived from GPS radio occultation data from CHAMP (2001-2008). The GW analysis is based on vertical detrending of the individual measured temperature profiles by applying a Gaussian filter in two different ways: (i) filtering of the complete temperature profiles and (ii) separate filtering of the profiles for the tropospheric and lower stratospheric parts. The separate filtering method significantly reduces the usually observed wave activity enhancement in the tropopause region which highly depends on the performance of the complete filtering method to reproduce the change in the temperature gradient at the tropopause. We only consider vertical wavelengths less than 10 km. The global mean Potential Energy in the tropopause region deduced with these different background temperatures will be analyzed, differences will be emphasized and possible error sources of the new method will be considered.

Peter A Sloan - One of the best experts on this subject based on the ideXlab platform.

  • mapping the site Specific Potential Energy landscape for chemisorbed and physisorbed aromatic molecules on the si 1 1 1 7 7 surface by time lapse stm
    Journal of Physics: Condensed Matter, 2015
    Co-Authors: Duncan Lock, Sumet Sakulsermsuk, Richard E. Palmer, Peter A Sloan
    Abstract:

    We present a scanning tunnelling microscope study of site-Specific thermal displacement (desorption or diffusion) of benzene, toluene, and chlorobenzene molecules on the Si(1 1 1)-7 × 7 surface. Through time-lapse STM imaging and automated image analysis we probe both the chemisorbed and the physisorbed states of these molecules. For the chemisorption to physisorption transition there are distinct site-Specific variations in the measured rates, however their kinetic origin is ambiguous. There is also significant variation in the competing rates out of the physisorbed state into chemisorption at the various surface sites, which we attribute to differences in site-Specific Arrhenius pre-factors. A prediction of the outcome of the competing rates and pre-factors for benzene over three hours matches experiment.

  • Mapping the site-Specific Potential Energy landscape for chemisorbed and physisorbed aromatic molecules on the Si(1 1 1)-7 × 7 surface by time-lapse STM.
    Journal of physics. Condensed matter : an Institute of Physics journal, 2014
    Co-Authors: Duncan Lock, Sumet Sakulsermsuk, Richard E. Palmer, Peter A Sloan
    Abstract:

    We present a scanning tunnelling microscope study of site-Specific thermal displacement (desorption or diffusion) of benzene, toluene, and chlorobenzene molecules on the Si(1 1 1)-7 × 7 surface. Through time-lapse STM imaging and automated image analysis we probe both the chemisorbed and the physisorbed states of these molecules. For the chemisorption to physisorption transition there are distinct site-Specific variations in the measured rates, however their kinetic origin is ambiguous. There is also significant variation in the competing rates out of the physisorbed state into chemisorption at the various surface sites, which we attribute to differences in site-Specific Arrhenius pre-factors. A prediction of the outcome of the competing rates and pre-factors for benzene over three hours matches experiment.

Antonia Faber - One of the best experts on this subject based on the ideXlab platform.

  • On the determination of gravity wave momentum flux from GPS radio occultation data
    Atmospheric Measurement Techniques, 2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. Global Positioning System (GPS) radio occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received by low Earth-orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions, offering the possibility of global monitoring of the vertical temperature structure and atmospheric wave parameters. The six-satellite constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. Here, a method for the determination of the real horizontal wavelength from three vertical profiles is applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep), and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.

  • A new approach to global gravity wave momentum flux determination from GPS radio occultation data
    2013
    Co-Authors: Antonia Faber, P. Llamedo, Torsten Schmidt, A. De La Torre, Jens Wickert
    Abstract:

    Abstract. GPS Radio Occultation (RO) is a well-established technique for obtaining global gravity wave (GW) information. RO uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Temperature profiles are derived with high vertical resolution and provide a global coverage under any weather conditions offering the possibility for global monitoring of the vertical temperature structure and atmospheric wave parameters. The six satellites constellation COSMIC/FORMOSAT-3 delivers approximately 2000 temperature profiles daily. In this study, we use a method to obtain global distributions of horizontal gravity wave wavelengths, to be applied in the determination of the vertical flux of horizontal momentum transported by gravity waves. The horizontal wavenumber is derived by the ratio of the phase shift and the spatial distance between adjacent temperature fluctuation profiles at a given altitude, following the method by Ern et al. (2004). A new method for the determination of the real horizontal wavelength from triads of vertical profiles is presented and applied to the COSMIC data. The horizontal and vertical wavelength, the Specific Potential Energy (Ep) and the vertical flux of horizontal momentum (MF) are calculated and their global distribution is discussed.