Dynamic Jovian Magnetosphere Responses to Enhanced Solar Wind Ram Pressure: Implications for Auroral Activities

• Published in: Geophysical research letters Vol. 49; no. 19
• Main Authors: Feng, Enhao, Zhang, Binzheng, Yao, Zhonghua, Delamere, Peter A., Zheng, Zhiqi, Brambles, Oliver J., Ye, Sheng‐Yi, Sorathia, Kareem A.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.10.2022
• Subjects: Alfvénic power; Auroral emissions; Auroral observations; Auroras; Breakdown; Brightening; Compression; Corotation; Dimming; Emission analysis; Emissions; enhanced solar wind; field‐aligned currents; global MHD simulation; Jovian aurora; Jovian magnetosphere; Jupiter; Mathematical models; Numerical simulations; Planetary auroras; Planetary magnetospheres; Pressure; Ram pressure; Simulation; Solar system; Solar wind
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL099858

The main emission (ME) of the Jovian aurora is thought to be related to the current system associated with the breakdown of plasma corotation in the middle magnetosphere. According to the mainstream corotation breakdown model, the intensity of the Jovian ME is expected to decrease when the solar wind (SW) ram pressure increases, which is not fully consistent with auroral observations. In addition to the field‐aligned current (FAC), Alfvénic power (AP) play an important role in regulating planetary auroral emissions. We use three‐dimensional global simulations to investigate how these proxies of auroral emission respond to enhanced SW ram pressure. We found that during SW compression, both FAC and AP experience up‐down‐up trends, which is not revealed by any previous simulations, while could potentially explain many observations. The results suggest that different Jovian auroral activities including brightening or dimming can be observed during SW compression period. Plain Language Summary Jupiter has the largest magnetosphere and the most intense auroral emissions in the solar system. However, the mechanisms of Jovian auroral emissions are not fully understood. The corotation breakdown model is expected to explain the main emission (ME) of the Jovian aurora. According to the mainstream corotation breakdown model, with enhanced solar wind (SW) ram pressure, the intensity of Jovian auroral ME is expected to decrease. However, observations have shown that aurora gets brighter to a certain extent. This inconsistency drives us to explore the auroral activities response to enhanced SW ram pressure through numerical simulations. Our results are consistent with many observations, and based on the simulation results we expect that the brightening or dimming of Jovian aurora may be predictable. The results can significantly improve our understanding on the Jovian magnetospheric response modes to enhanced SW ram pressure, and the Jovian auroral mechanisms. Key Points High resolution global magnetohydrodynamics model of Jovian magnetosphere that can reproduce the radial density profile of Jovian magnetosphere is conducted Hemispheric field‐aligned currents (FACs) and Alfvénic power (AP) exhibit non‐linear responses during solar wind compression (SWC) The responses of both FAC and AP to SWC shows agreement with many auroral observations