The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
E J Lund - One of the best experts on this subject based on the ideXlab platform.
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nightside Auroral Zone and polar cap ion outflow as a function of substorm size and phase
Journal of Geophysical Research, 2004Co-Authors: G R Wilson, D M Ober, E J LundAbstract:[1] Because the high latitude ionosphere is an important source of plasma for the magnetosphere under active conditions, we have undertaken a study of the way ion outflow from the nightside Auroral Zone and polar cap respond to substorm activity. We have combined data from the Ultraviolet Imager (UVI) on Polar with ion upflow measurements from the TEAMS instrument on the FAST spacecraft to construct a picture of ion upflow from these regions as a function of substorm size and as a function of time relative to substorm onset. We use data taken during solar minimum in the northern hemisphere between December 1996 and February 1997. We find that the total nightside Auroral Zone ion outflow rate (averaged over substorm phase) depends on the size of the substorm, increasing by about a factor of 10 for both O+ and H+ from the smallest to the largest substorms in our study. The combined outflow rate from both the polar cap and the nightside Auroral Zone goes up by a factor of 7 for both ions for the same change in conditions. Regardless of storm size, the nightside Auroral Zone outflow rate increases by about a factor of 2 after onset, reaching its peak level after about 20 min. These results indicate that the change in the nightside Auroral Zone ion outflow rate that accompanies substorm onset is not as significant as the change from low to high magnetic activity. As a consequence, the prompt increase in the near earth plasma sheet energy density of O+ and H+ ions that accompanies onset [Daglis and Axford, 1996] is likely due to local energization of ions already present rather than to the sudden arrival and energization of fresh ionospheric plasma.
M. Temerin - One of the best experts on this subject based on the ideXlab platform.
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Ponderomotive effects on ion acceleration in the Auroral Zone
Geophysical Research Letters, 1993Co-Authors: M. TemerinAbstract:Low frequency (ω 100 mV/m) Alfven waves occur in the Auroral Zone. Such waves have a ponderomotive effect, on both ions and electrons. In the region between the large wave field and the ionosphere, the ponderomotive force accelerates electrons downward and ions upward, which produces an ambipolar electric field. The combined effect is to produce a differential acceleration between O+ and H+ with the O+ accelerated more out of the ionosphere. The typical resulting energization for O+ is tens of eV, which is sufficient for the ions to escape the ionosphere. We demonstrate this by means of analysis and test-particle calculation.
G R Wilson - One of the best experts on this subject based on the ideXlab platform.
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nightside Auroral Zone and polar cap ion outflow as a function of substorm size and phase
Journal of Geophysical Research, 2004Co-Authors: G R Wilson, D M Ober, E J LundAbstract:[1] Because the high latitude ionosphere is an important source of plasma for the magnetosphere under active conditions, we have undertaken a study of the way ion outflow from the nightside Auroral Zone and polar cap respond to substorm activity. We have combined data from the Ultraviolet Imager (UVI) on Polar with ion upflow measurements from the TEAMS instrument on the FAST spacecraft to construct a picture of ion upflow from these regions as a function of substorm size and as a function of time relative to substorm onset. We use data taken during solar minimum in the northern hemisphere between December 1996 and February 1997. We find that the total nightside Auroral Zone ion outflow rate (averaged over substorm phase) depends on the size of the substorm, increasing by about a factor of 10 for both O+ and H+ from the smallest to the largest substorms in our study. The combined outflow rate from both the polar cap and the nightside Auroral Zone goes up by a factor of 7 for both ions for the same change in conditions. Regardless of storm size, the nightside Auroral Zone outflow rate increases by about a factor of 2 after onset, reaching its peak level after about 20 min. These results indicate that the change in the nightside Auroral Zone ion outflow rate that accompanies substorm onset is not as significant as the change from low to high magnetic activity. As a consequence, the prompt increase in the near earth plasma sheet energy density of O+ and H+ ions that accompanies onset [Daglis and Axford, 1996] is likely due to local energization of ions already present rather than to the sudden arrival and energization of fresh ionospheric plasma.
M. Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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On the origin of the high‐altitude electric field fluctuations in the Auroral Zone
Journal of Geophysical Research: Space Physics, 1996Co-Authors: Anita Aikio, Lars Blomberg, Göran Marklund, M. YamauchiAbstract:Intense fluctuations in the electric field at high altitudes in the Auroral Zone are frequently measured by the Viking satellite. We have made an analysis of the origin of electric and magnetic flu ...
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on the origin of the high altitude electric field fluctuations in the Auroral Zone
Journal of Geophysical Research, 1996Co-Authors: Anita Aikio, Lars Blomberg, Göran Marklund, M. YamauchiAbstract:Intense fluctuations in the electric field at high altitudes in the Auroral Zone are frequently measured by the Viking satellite. We have made an analysis of the origin of electric and magnetic flu ...
D M Ober - One of the best experts on this subject based on the ideXlab platform.
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nightside Auroral Zone and polar cap ion outflow as a function of substorm size and phase
Journal of Geophysical Research, 2004Co-Authors: G R Wilson, D M Ober, E J LundAbstract:[1] Because the high latitude ionosphere is an important source of plasma for the magnetosphere under active conditions, we have undertaken a study of the way ion outflow from the nightside Auroral Zone and polar cap respond to substorm activity. We have combined data from the Ultraviolet Imager (UVI) on Polar with ion upflow measurements from the TEAMS instrument on the FAST spacecraft to construct a picture of ion upflow from these regions as a function of substorm size and as a function of time relative to substorm onset. We use data taken during solar minimum in the northern hemisphere between December 1996 and February 1997. We find that the total nightside Auroral Zone ion outflow rate (averaged over substorm phase) depends on the size of the substorm, increasing by about a factor of 10 for both O+ and H+ from the smallest to the largest substorms in our study. The combined outflow rate from both the polar cap and the nightside Auroral Zone goes up by a factor of 7 for both ions for the same change in conditions. Regardless of storm size, the nightside Auroral Zone outflow rate increases by about a factor of 2 after onset, reaching its peak level after about 20 min. These results indicate that the change in the nightside Auroral Zone ion outflow rate that accompanies substorm onset is not as significant as the change from low to high magnetic activity. As a consequence, the prompt increase in the near earth plasma sheet energy density of O+ and H+ ions that accompanies onset [Daglis and Axford, 1996] is likely due to local energization of ions already present rather than to the sudden arrival and energization of fresh ionospheric plasma.
