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The responses of ionospheric topside diffusive fluxes to two geomagnetic storms in October 2002
Author(s) -
Chen GuangMing,
Xu Jiyao,
Wang Wenbin,
Lei Jiuhou,
Zhang ShunRong
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020013
Subject(s) - millstone hill , daytime , ionosphere , geomagnetic storm , storm , atmospheric sciences , incoherent scatter , flux (metallurgy) , electron density , ambipolar diffusion , quiet , earth's magnetic field , physics , electron , geophysics , meteorology , magnetic field , chemistry , astronomy , organic chemistry , quantum mechanics
O + field‐aligned ambipolar diffusive velocities V d and fluxes Ф d in the topside ionosphere have been calculated from the observed profiles of electron density, ion, and electron temperatures during a 30 day incoherent scatter radar experiment conducted at Millstone Hill (288.5°E, 42.6°N) from 4 October to 4 November 2002. Two geomagnetic storms took place during this period. During the negative phases (depleted electron densities) of these two storms, the magnitudes of the daytime upward V d and Ф d were less than their averaged quiet time values. Whereas at nighttime, the downward V d and Ф d were sometimes larger than the averaged quiet time values. The variations in diffusive velocity and flux during the storm main and recovery phases were caused by changes in the ionospheric scale height or the shapes of ionospheric density profiles. The negative storm effect further reduced daytime diffusive flux. During these two storms, positive ionosphere phases (enhanced electron densities) were also observed. The diffusive velocity was much smaller during the period of positive storm effect, which led to a smaller diffusive flux than the quiet time one, although electron density was higher. It appears that storm time variations in diffusive velocity were more the results of storm time changes in the plasma vertical profile, rather than the cause of these plasma density changes.