Ampère force exerted by geomagnetic Sq currents and thermospheric pressure difference. Issue 5 (6th May 2015)

• Record Type: Journal Article
• Authors: Takeda, Masahiko
• Is Part Of: Journal of geophysical research. Volume 120:Issue 5(2015:May)
• Page Start: 3847
• Page End: 3853
• Publication Date: 2015-05-06
• Subjects: Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2014JA020952
• Languages: English
• ISSNs: 2169-9380

Abstract

<abstract abstract-type="main" id="jgra51762-abs-0001"> <title>Abstract</title> <p id="jgra51762-para-0001">The Ampère force exerted by meridional <italic>Sq</italic> currents was estimated, and its relationship with a neutral pressure difference was examined. It was found that the annual Ampère force correlates very well with the difference between its maximum and minimum pressures integrated above 120 km for solar activity variation. Furthermore, these two values were almost the same around the <italic>Sq</italic> current vortex during the equinox. This means that the pressure difference balances with Ampère force, and thus, a neutral wind blows roughly in the opposite direction of the pressure gradient. As a result, the intensity of the resultant ionospheric dynamo current is controlled by the pressure difference, and thus, it is possible to infer the pressure difference from the geomagnetic field only at least the annual mean in equinox. At Kakioka, there was seasonal variation such that the pressure difference in the local summer and winter was smaller and larger than the Ampère force, respectively. This characteristic is likely due to the contribution of the interhemispheric field‐aligned currents driven by the ionospheric dynamo to the <italic>Sq</italic> field.</p> </abstract>