The Experts below are selected from a list of 6903 Experts worldwide ranked by ideXlab platform

Amine Laghriyeb - One of the best experts on this subject based on the ideXlab platform.

  • ionospheric and thermospheric response to the 27 28 february 2014 geomagnetic storm over north africa
    Annales Geophysicae, 2018
    Co-Authors: Khalifa Malki, Aziza Bounhir, Z Benkhaldoun, Jonathan J Makela, N Vilmer, Daniel J Fisher, Mohamed Kaab, Khaoula Elbouyahyaoui, Brian J Harding, Amine Laghriyeb
    Abstract:

    Abstract. The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was due to the arrival at the Earth of the shock of a coronal mass ejection (CME) associated with the solar flare event on 25 February 2014. A Fabry–Perot interferometer located at the Oukaimeden Observatory (31.206° N, 7.866° W; 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on observations of the 630 nm red line emission. A wide-angle imaging system records images of the 630 nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21:00 to 01:00 LT and a westward flow from 22:00 to 03:00 LT. The equatorial wind speed reaches a maximum of 120 m s−1 for the meridional component at 22:00 LT, after the zonal wind reverses to the westward direction. Shortly after 00:00 LT a maximum westward speed of 80 m s−1 was achieved for the zonal component of the wind. The features of the winds are typical of traveling Atmospheric Disturbance (TAD)-induced circulation; the first TAD coming from the Northern Hemisphere reaches the site at 21:00 LT and a second one coming from the Southern Hemisphere reaches the site at about 00:00 LT. We estimate the propagation speed of the northern TAD to be 550 m s−1. We compared the winds to the DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in the drift direction in an observed equatorial plasma bubble (EPB). Total electron content (TEC) measurements of a GPS station installed in Morocco, at Rabat (33.998° N, 6.853° W), revealed a positive storm.

  • Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm over north Africa
    Copernicus Publications, 2018
    Co-Authors: Khalifa Malki, Aziza Bounhir, Z Benkhaldoun, Jonathan J Makela, N Vilmer, Daniel J Fisher, Mohamed Kaab, Khaoula Elbouyahyaoui, Brian J Harding, Amine Laghriyeb
    Abstract:

    The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was due to the arrival at the Earth of the shock of a coronal mass ejection (CME) associated with the solar flare event on 25 February 2014. A Fabry–Perot interferometer located at the Oukaïmeden Observatory (31.206° N, 7.866° W; 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on observations of the 630 nm red line emission. A wide-angle imaging system records images of the 630 nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21:00 to 01:00 LT and a westward flow from 22:00 to 03:00 LT. The equatorial wind speed reaches a maximum of 120 m s−1 for the meridional component at 22:00 LT, after the zonal wind reverses to the westward direction. Shortly after 00:00 LT a maximum westward speed of 80 m s−1 was achieved for the zonal component of the wind. The features of the winds are typical of traveling Atmospheric Disturbance (TAD)-induced circulation; the first TAD coming from the Northern Hemisphere reaches the site at 21:00 LT and a second one coming from the Southern Hemisphere reaches the site at about 00:00 LT. We estimate the propagation speed of the northern TAD to be 550 m s−1. We compared the winds to the DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in the drift direction in an observed equatorial plasma bubble (EPB). Total electron content (TEC) measurements of a GPS station installed in Morocco, at Rabat (33.998° N, 6.853° W), revealed a positive storm.

I V Fine - One of the best experts on this subject based on the ideXlab platform.

  • northern adriatic meteorological tsunamis assessment of their potential through ocean modeling experiments
    Journal of Geophysical Research, 2015
    Co-Authors: Jadranka Sepic, Ivica Vilibic, I V Fine
    Abstract:

    Potential for generation of meteotsunami waves via open ocean resonance has been documented for the shallow northern Adriatic, based on a set of barotropic numerical modeling experiments. Model simulations were forced by a bell-shaped traveling Atmospheric (air pressure, wind) Disturbance, with shape and propagation parameters chosen in accordance with measurements done during several observed northern Adriatic meteotsunamis. Air pressure Disturbances were found to generate much larger meteotsunami waves than wind Disturbances, with wind Disturbances having a limited influence in the very coastal and shallow areas only. Numerical simulations reveal that the most important factor for generation of large meteotsunami waves is matching between the speed of the Atmospheric Disturbance and the speed of long-ocean waves. Already a small (∼10%) deviation from resonant conditions stops the wave growth and dramatically decreases height of predicted waves. A train of Atmospheric Disturbances can significantly increase maximum wave heights at selected locations at which multiple reflections and superimpositions of meteotsunami waves occur. Sensitivity of model simulations to resonant conditions and limited cross-propagation width of Atmospheric Disturbance explain the localization of destructive meteotsunami waves in a limited area during destructive historic events. Mapping of maximum predicted wave heights indicates places with large meteotsunami hazard potential, matching the locations where real events were observed, and may be a useful tool for assessing vulnerability and risks in coastal areas during extreme sea level events.

Khalifa Malki - One of the best experts on this subject based on the ideXlab platform.

  • ionospheric and thermospheric response to the 27 28 february 2014 geomagnetic storm over north africa
    Annales Geophysicae, 2018
    Co-Authors: Khalifa Malki, Aziza Bounhir, Z Benkhaldoun, Jonathan J Makela, N Vilmer, Daniel J Fisher, Mohamed Kaab, Khaoula Elbouyahyaoui, Brian J Harding, Amine Laghriyeb
    Abstract:

    Abstract. The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was due to the arrival at the Earth of the shock of a coronal mass ejection (CME) associated with the solar flare event on 25 February 2014. A Fabry–Perot interferometer located at the Oukaimeden Observatory (31.206° N, 7.866° W; 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on observations of the 630 nm red line emission. A wide-angle imaging system records images of the 630 nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21:00 to 01:00 LT and a westward flow from 22:00 to 03:00 LT. The equatorial wind speed reaches a maximum of 120 m s−1 for the meridional component at 22:00 LT, after the zonal wind reverses to the westward direction. Shortly after 00:00 LT a maximum westward speed of 80 m s−1 was achieved for the zonal component of the wind. The features of the winds are typical of traveling Atmospheric Disturbance (TAD)-induced circulation; the first TAD coming from the Northern Hemisphere reaches the site at 21:00 LT and a second one coming from the Southern Hemisphere reaches the site at about 00:00 LT. We estimate the propagation speed of the northern TAD to be 550 m s−1. We compared the winds to the DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in the drift direction in an observed equatorial plasma bubble (EPB). Total electron content (TEC) measurements of a GPS station installed in Morocco, at Rabat (33.998° N, 6.853° W), revealed a positive storm.

  • Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm over north Africa
    Copernicus Publications, 2018
    Co-Authors: Khalifa Malki, Aziza Bounhir, Z Benkhaldoun, Jonathan J Makela, N Vilmer, Daniel J Fisher, Mohamed Kaab, Khaoula Elbouyahyaoui, Brian J Harding, Amine Laghriyeb
    Abstract:

    The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was due to the arrival at the Earth of the shock of a coronal mass ejection (CME) associated with the solar flare event on 25 February 2014. A Fabry–Perot interferometer located at the Oukaïmeden Observatory (31.206° N, 7.866° W; 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on observations of the 630 nm red line emission. A wide-angle imaging system records images of the 630 nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21:00 to 01:00 LT and a westward flow from 22:00 to 03:00 LT. The equatorial wind speed reaches a maximum of 120 m s−1 for the meridional component at 22:00 LT, after the zonal wind reverses to the westward direction. Shortly after 00:00 LT a maximum westward speed of 80 m s−1 was achieved for the zonal component of the wind. The features of the winds are typical of traveling Atmospheric Disturbance (TAD)-induced circulation; the first TAD coming from the Northern Hemisphere reaches the site at 21:00 LT and a second one coming from the Southern Hemisphere reaches the site at about 00:00 LT. We estimate the propagation speed of the northern TAD to be 550 m s−1. We compared the winds to the DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in the drift direction in an observed equatorial plasma bubble (EPB). Total electron content (TEC) measurements of a GPS station installed in Morocco, at Rabat (33.998° N, 6.853° W), revealed a positive storm.

Ivica Vilibic - One of the best experts on this subject based on the ideXlab platform.

  • northern adriatic meteorological tsunamis assessment of their potential through ocean modeling experiments
    Journal of Geophysical Research, 2015
    Co-Authors: Jadranka Sepic, Ivica Vilibic, I V Fine
    Abstract:

    Potential for generation of meteotsunami waves via open ocean resonance has been documented for the shallow northern Adriatic, based on a set of barotropic numerical modeling experiments. Model simulations were forced by a bell-shaped traveling Atmospheric (air pressure, wind) Disturbance, with shape and propagation parameters chosen in accordance with measurements done during several observed northern Adriatic meteotsunamis. Air pressure Disturbances were found to generate much larger meteotsunami waves than wind Disturbances, with wind Disturbances having a limited influence in the very coastal and shallow areas only. Numerical simulations reveal that the most important factor for generation of large meteotsunami waves is matching between the speed of the Atmospheric Disturbance and the speed of long-ocean waves. Already a small (∼10%) deviation from resonant conditions stops the wave growth and dramatically decreases height of predicted waves. A train of Atmospheric Disturbances can significantly increase maximum wave heights at selected locations at which multiple reflections and superimpositions of meteotsunami waves occur. Sensitivity of model simulations to resonant conditions and limited cross-propagation width of Atmospheric Disturbance explain the localization of destructive meteotsunami waves in a limited area during destructive historic events. Mapping of maximum predicted wave heights indicates places with large meteotsunami hazard potential, matching the locations where real events were observed, and may be a useful tool for assessing vulnerability and risks in coastal areas during extreme sea level events.

  • wind versus air pressure seiche triggering in the middle adriatic coastal waters
    Journal of Marine Systems, 2005
    Co-Authors: Ivica Vilibic, Nenad Domijan, Srđan Cupic
    Abstract:

    Strong air pressure and sea level oscillations, which occurred in the Middle Adriatic region during the storm passage on 21 August 2004, were recorded at a number of meteorological and tide gauge stations. Large sea levels measured were related to the Proudman and harbour resonances, being also observed during the past event on 27 June 2003. Both cases were characterized by a travelling air pressure Disturbance, but a part of the oscillations in August 2004 case were a result of short-lasting strong winds which were absent during the event in June 2003. Occurrence of a strong 4-h fundamental oscillation of the whole region versus weak harbour seiches was a result of the shape of travelling air pressure Disturbance: it looked like a box-function containing large energies in a low frequency domain, whereas the event in June 2003 was characterized by a cosine-like Disturbance, redistributing the energy towards higher frequencies. Using a numerical model it is shown that the strength of 4-h oscillation is sensitive to the speed of travelling Atmospheric Disturbance and to its incoming direction. The largest amplitudes were modelled for a speed of 13 m/s, indicating that inner part of the region is possibly the best place for occurrence of the Proudman resonance.

X U Zongfei - One of the best experts on this subject based on the ideXlab platform.

  • output feedback controller design and simulation for uav consider Atmospheric Disturbance
    Computer Simulation, 2010
    Co-Authors: X U Zongfei
    Abstract:

    UAV in flight is effeced by Atmospheric Disturbance;this paper studied Atmospheric turbulence on the impact of UAV flight,longitudinal small perturbation linear motion equations are established based on Dryden turbulance model,in order to contain the interference of Atmospheric turbulence on the UAV to ensure flight stability,the H∞ control theory is applied.Output feedback H∞ control algorithm is used in design and simulation.Results show that the control method used is effective on inhibiting the interference of Atmospheric turbulence on UAV,so that the flight control system has good stability and robustness.