The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform

Tien Khee Ng - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Turbulent-Flow-Induced Scintillation on Deep-Ocean Wireless Optical Communication
    Journal of Lightwave Technology, 2019
    Co-Authors: Yang Weng, Omar Alkhazragi, Tien Khee Ng
    Abstract:

    The use of autonomous underwater vehicles (AUVs) is highly desirable for collecting data from seafloor sensor platforms within a close range. With the recent innovations in underwater wireless optical communication (UWOC) for deep-sea exploration, UWOC could be used in conjunction with AUVs for high-speed data uploads near the surface. In addition to absorption and scattering effects, UWOC undergoes scintillation induced by temperature- and salinity-related turbulence. However, studies on scintillation have been limited to emulating channels with uniform temperature and salinity gradients, rather than incorporating the effects of turbulent motion. Such turbulent flow results in an Ocean Mixing Process that degrades optical communication. This study presents a turbulent model for investigating the impact of vehicle-motion-induced turbulence via the turbulent kinetic energy dissipation rate. This scintillation-related parameter offers a representation of the change in the refractive index due to the turbulent flow and Ocean Mixing. Monte Carlo simulations are carried out to validate the impact of turbulent flow on optical scintillation. In experimental measurements, the scintillation index (SI) and signal-to-noise ratio (SNR) are similar with (SI = 0.4824; SNR = 5.56) and without (SI = 0.4823; SNR = 5.87) water Mixing under uniform temperature channels. By introducing a temperature gradient of 4 °C, SI (SNR) with and without turbulent flow changed to 0.5417 (5.06) and 0.8790 (3.40), respectively. The experimental results show a similar trend to the simulation results. Thus, turbulent flow was shown to significantly impact underwater optical communications.

Yang Weng - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Turbulent-Flow-Induced Scintillation on Deep-Ocean Wireless Optical Communication
    Journal of Lightwave Technology, 2019
    Co-Authors: Yang Weng, Omar Alkhazragi, Tien Khee Ng
    Abstract:

    The use of autonomous underwater vehicles (AUVs) is highly desirable for collecting data from seafloor sensor platforms within a close range. With the recent innovations in underwater wireless optical communication (UWOC) for deep-sea exploration, UWOC could be used in conjunction with AUVs for high-speed data uploads near the surface. In addition to absorption and scattering effects, UWOC undergoes scintillation induced by temperature- and salinity-related turbulence. However, studies on scintillation have been limited to emulating channels with uniform temperature and salinity gradients, rather than incorporating the effects of turbulent motion. Such turbulent flow results in an Ocean Mixing Process that degrades optical communication. This study presents a turbulent model for investigating the impact of vehicle-motion-induced turbulence via the turbulent kinetic energy dissipation rate. This scintillation-related parameter offers a representation of the change in the refractive index due to the turbulent flow and Ocean Mixing. Monte Carlo simulations are carried out to validate the impact of turbulent flow on optical scintillation. In experimental measurements, the scintillation index (SI) and signal-to-noise ratio (SNR) are similar with (SI = 0.4824; SNR = 5.56) and without (SI = 0.4823; SNR = 5.87) water Mixing under uniform temperature channels. By introducing a temperature gradient of 4 °C, SI (SNR) with and without turbulent flow changed to 0.5417 (5.06) and 0.8790 (3.40), respectively. The experimental results show a similar trend to the simulation results. Thus, turbulent flow was shown to significantly impact underwater optical communications.

Omar Alkhazragi - One of the best experts on this subject based on the ideXlab platform.

  • Impact of Turbulent-Flow-Induced Scintillation on Deep-Ocean Wireless Optical Communication
    Journal of Lightwave Technology, 2019
    Co-Authors: Yang Weng, Omar Alkhazragi, Tien Khee Ng
    Abstract:

    The use of autonomous underwater vehicles (AUVs) is highly desirable for collecting data from seafloor sensor platforms within a close range. With the recent innovations in underwater wireless optical communication (UWOC) for deep-sea exploration, UWOC could be used in conjunction with AUVs for high-speed data uploads near the surface. In addition to absorption and scattering effects, UWOC undergoes scintillation induced by temperature- and salinity-related turbulence. However, studies on scintillation have been limited to emulating channels with uniform temperature and salinity gradients, rather than incorporating the effects of turbulent motion. Such turbulent flow results in an Ocean Mixing Process that degrades optical communication. This study presents a turbulent model for investigating the impact of vehicle-motion-induced turbulence via the turbulent kinetic energy dissipation rate. This scintillation-related parameter offers a representation of the change in the refractive index due to the turbulent flow and Ocean Mixing. Monte Carlo simulations are carried out to validate the impact of turbulent flow on optical scintillation. In experimental measurements, the scintillation index (SI) and signal-to-noise ratio (SNR) are similar with (SI = 0.4824; SNR = 5.56) and without (SI = 0.4823; SNR = 5.87) water Mixing under uniform temperature channels. By introducing a temperature gradient of 4 °C, SI (SNR) with and without turbulent flow changed to 0.5417 (5.06) and 0.8790 (3.40), respectively. The experimental results show a similar trend to the simulation results. Thus, turbulent flow was shown to significantly impact underwater optical communications.

Akiyoshi Wada - One of the best experts on this subject based on the ideXlab platform.

  • Diurnal sea surface temperature variation and its impact on the atmosphere and Ocean: A review
    Journal of Oceanography, 2007
    Co-Authors: Yoshimi Kawai, Akiyoshi Wada
    Abstract:

    The importance of the diurnal variability of sea surface temperature (SST) on air-sea interaction is now being increasingly recognized. This review synthesizes knowledge of the diurnal SST variation, mainly paying attention to its impact on the atmosphere or the Ocean. Diurnal SST warming becomes evident when the surface wind is weak and insolation is strong. Recent observations using satellite data and advanced instruments have revealed that a large diurnal SST rise occurs over wide areas in a specific season, and in an extreme case the diurnal amplitude of SST exceeds 5 K. The large diurnal SST rise can lead to an increase in net surface heat flux from the Ocean of 50–60 Wm^−2 in the daytime. The temporal mean of the increase exceeds 10 Wm^−2, which will be non-negligible for the atmosphere. A few numerical experiments have indicated that the diurnal SST variation can modify atmospheric properties over the Pacific warm pool or a coastal sea, but the Processes underlying the modification have not yet been investigated in detail. Furthermore, it has been shown that the diurnal change of Ocean Mixing Process near the surface must be considered correctly in order to reproduce SST variations on an intraseasonal scale in a numerical model. The variation of mixed-layer properties on the daily scale is nonlinearly related to the intraseasonal variability. The mixed-layer deepening/shoaling Process on the daily scale will also be related to biological and material circulation Processes.

Yoshimi Kawai - One of the best experts on this subject based on the ideXlab platform.

  • Diurnal sea surface temperature variation and its impact on the atmosphere and Ocean: A review
    Journal of Oceanography, 2007
    Co-Authors: Yoshimi Kawai, Akiyoshi Wada
    Abstract:

    The importance of the diurnal variability of sea surface temperature (SST) on air-sea interaction is now being increasingly recognized. This review synthesizes knowledge of the diurnal SST variation, mainly paying attention to its impact on the atmosphere or the Ocean. Diurnal SST warming becomes evident when the surface wind is weak and insolation is strong. Recent observations using satellite data and advanced instruments have revealed that a large diurnal SST rise occurs over wide areas in a specific season, and in an extreme case the diurnal amplitude of SST exceeds 5 K. The large diurnal SST rise can lead to an increase in net surface heat flux from the Ocean of 50–60 Wm^−2 in the daytime. The temporal mean of the increase exceeds 10 Wm^−2, which will be non-negligible for the atmosphere. A few numerical experiments have indicated that the diurnal SST variation can modify atmospheric properties over the Pacific warm pool or a coastal sea, but the Processes underlying the modification have not yet been investigated in detail. Furthermore, it has been shown that the diurnal change of Ocean Mixing Process near the surface must be considered correctly in order to reproduce SST variations on an intraseasonal scale in a numerical model. The variation of mixed-layer properties on the daily scale is nonlinearly related to the intraseasonal variability. The mixed-layer deepening/shoaling Process on the daily scale will also be related to biological and material circulation Processes.