Predicting the strength and peak time of geomagnetic activity for the 11-year cycle is important in space weather service. The maximum aa (Ap) index is found to be well correlated to the preceding minimum. If the data point for cycle 24 were not considered, the rise time of the Ap index would be weakly correlated to the following maximum. As a result, the maximum aa (Ap) index for cycle 25 is predicted to be 26.9 ± 2.6 (17.3 ± 1.8 ± 1.2), occurring around April 2025 ± 32 months.

Numerical simulation have been used to investigate some acceleration mechanisms in order to explain the origin of the energized backstreaming ion observed at the Earth’s bow shock. This paper used test particules in two different configurations with self-consistent and fixed shock front profiles. The comparison of these two configurations allows to analyze in details the impact of the shock front non stationarity and the role of the built-up electric field in the acceleration process.

This paper is the first to study how representation of magnetic local time (MLT) dependency of electron precipitation impacts middle atmospheric ozone response on monthly time scales. We use state-of-the-art chemistry-climate model with detailed lower ionospheric chemistry for an advanced representation of atmospheric impacts of electron forcing. We find that electron forcing that ignores MLT-dependency will still provide an accurate ozone response for long-term climate simulations.

Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.

The CSES observed ionospheric Pc1 waves near the wave injection regions in conjugate hemispheres during the recovery phase of the geomagnetic storm on 27 August 2018. The Pc1s are found to be Alfven waves with mixed polarization, propagating along background magnetic lines down into the ionosphere. We suggest the possible sources of Pc1 are EMIC waves generated near the plasmapause by the outward expansion of the plasmasphere into the ring current during the recovery phase of geomagnetic storm.

We use satellite data to analyze the precursory anomalies of M7.1 Yushu earthquake occurred in western China through analyzing signal to noise ratio (SNR), and we use full wave model to illustrate a possible mechanism how the anomalies occurred. The results show SNR of VLF radio waves in the ionosphere decreased before Yushu earthquake. The full-wave simulation results confirm the electron density variation in the lower ionosphere will affect the SNR of VLF radio signals.

Identifying ionospheric disturbances associated with an earthquake is a useful and challenging work. A new decomposition and nonlinear fitting method has been developed to analyze ionospheric total electron content (TEC) data, and to extract disturbances that are likely related to Mw7.2 Mexico earthquake occurred on April 4, 2010. We found a unique TEC depletion that occurred around the epicenter on March 25, which cannot be explained by lower atmosphere wave or geomagnetic activity forcing.

Low Latitude Aurorae (LLA) were uncommon phenomenon not well known and understood in 1780. During our historical manuscripts research of high atmospheric phenomena we came across a document reporting an observation done by the abbot Rozier in Beausejour, France, on 15/08/1780. Thanks to the accuracy of his report, we were able to confirm it was a white, with two bands structure LLA. Due to the few existing geomagnetic and solar observations it is a useful new geomagnetic activity proxy data.