Effect of intrinsic magnetic field decrease on the low‐ to middle‐latitude upper atmosphere dynamics simulated by GAIA. Issue 9 (30th September 2017)

• Record Type: Journal Article
• Authors: Tao, Chihiro; Jin, Hidekatsu; Shinagawa, Hiroyuki; Fujiwara, Hitoshi; Miyoshi, Yasunobu
• Is Part Of: Journal of geophysical research. Volume 122:Issue 9(2017)
• Page Start: 9751
• Page End: 9762
• Publication Date: 2017-09-30
• Subjects: GAIA -- thermosphere -- ionosphere -- simulation -- intrinsic magnetic field; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2017JA024278
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The effects of decreasing the intrinsic magnetic field on the upper atmospheric dynamics at low to middle latitudes are investigated using the Ground‐to‐topside model of Atmosphere and Ionosphere for Aeronomy (GAIA). GAIA incorporates a meteorological reanalysis data set at low altitudes (<30 km), which enables us to investigate the atmospheric response to various waves under dynamic and chemical interactions with the ionosphere. In this simulation experiment, we reduced the magnetic field strength to as low as 10% of the current value. The averaged neutral velocity, density, and temperature at low to middle latitudes at 300 km altitude show little change with the magnetic field variation, while the dynamo field, current density, and the ionospheric conductivities are modified significantly. The wind velocity and tidal wave amplitude in the thermosphere remain large owing to the small constraint on plasma motion for a small field. On the other hand, the superrotation feature at the dip equator is weakened by 20% for a 10% magnetic field because the increase in ion drag for the small magnetic field prevents the superrotation. Key Points: The dependence of thermosphere/ionosphere dynamics on the intrinsic magnetic field is investigated using the whole atmospheric model GAIA The wind velocity and tidal wave amplitude in the thermosphere remain large due to the small constraint on plasma motion for a small field The superrotation feature at the dip equator is weakened owing to a large ion drag for a small field case