Global Modeling of Equatorial Spread F with SAMI3/WACCM-X

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Tuesday, June 2, 2020

We report the first results of a global ionosphere/thermosphere simulation study that self-consistently generates large-scale equatorial spread F (ESF) plasma bubbles in the post-sunset ionosphere. The coupled model comprises the ionospheric code SAMI3 and the atmosphere/thermosphere code WACCM-X. Two cases are modeled for different seasons and geophysical conditions: the March case (low solar activity:F10.7 = 70) and the July case (high solar activity: F10.7 = 170). We find that equatorial plasma bubbles formed and penetrated into the topside F layer for the March case but not the July case. For the March case a series of bubbles formed in the Atlantic sector with irregularity spacings in the range 400 - 1200 km, rose to over 800 km, and persisted until after midnight. These results are consistent with recent GOLD observations. Calculation of the generalized Rayleigh-Taylor instability (GRTI) growth rate shows that the e-folding time was much shorter for the March case than the July case.

Graphic image of the comparison of 135.6 nm emissions
Comparison of 135.6 nm emissions from the SAMI3/WACCM-X simulation for the March case (left and middle panels) and GOLD emission data (right panel) observed from geosynchronous orbit [Eastes et al., 2019].

Publication Name: Geophysical Research Letters
First HAO Author's Name: Hanli Liu

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