The High-energy Particle Detector (HEPD) on board the China Seismo-Electromagnetic Satellite (CSES-01)—launched on 2018 February 2—is a light and compact payload suitable for measuring electrons (3–100 MeV), protons (30–250 MeV), and light nuclei (up to a few hundreds of MeV). The Sun-synchronous orbit and large acceptance allow HEPD to measure cosmic-ray particles near the ±65° latitude limit for a fair amount of time per day. In this work, three semiannual galactic hydrogen energy spectra between ∼40 and 250 MeV are presented, including a comparison with theoretical spectra from HelMod, a 2D Monte Carlo model developed to simulate the solar modulation of cosmic rays throughout the heliosphere. To our knowledge, these are the first hydrogen energy spectra below 250 MeV measured at 1 au between 2018 and 2020.

<p>On August 25, 2018 the interplanetary counterpart of the August 20, 2018 Coronal Mass Ejection (CME) hit the Earth, giving rise to a strong geomagnetic storm. We present a description of the whole sequence of events from the Sun to the ground as well as a detailed analysis of the onserved effects on the Earth's environment by using a multi instrumental approach. <br>We studied the ICME propagation in the interplanetary space up to the analysis of its effects in the magnetosphere, ionosphere and at ground. To accomplish this task, we used ground and space collected data, including data from CSES (China Seismo Electric Satellite), launched on February 11, 2018. We found a direct connection between the ICME impact point onto the magnetopause and the pattern of the Earth's polar electrojects. Using the Tsyganenko TS04 model prevision, we were able to correctly identify the principal magnetospheric current system activating during the different phases of the geomagnetic storm. Moreover, we analyzed the space-weather effects associated with the August 25, 2018 solar event in terms of evaluation geomagnetically induced currents (GIC) and identification of possible GPS loss of lock. We found that, despite the strong geomagnetic storm, no loss of lock has been detected. On the contrary, the GIC hazard was found to be potentially more dangerous than other past, more powerful solar events, such as the St. Patrick geomagnetic storm, especially at latitudes higher than $60^\circ$ in the European sector.</p>

Significant evidence of ionosphere disturbance in connection to intense seismic events have been detected since two decades. It is generally believed that the energy transfer can be due to Acoustic Gravity Waves (AGW) excited at ground level by the earthquakes. In spite of the statistical evidence of the detected perturbations, the coupling between lithosphere and atmosphere has not been so far properly explained by an accurate enough model. In this paper, for the first time, we show the result of an analytical-quantitative model that describes how the pressure and density disturbance is generated in the lower atmosphere by the ground motion associated to earthquakes. The direct comparison between observed and modelled vertical profiles of the atmospheric temperature shows the capability of the model to accurately reproduce, with an high statistical significance, the observed temperature fluctuations induced by strong earthquakes.

Mercury's environment is characterized by a high variability and strength of the solar forcing. Its magnetosphere is completely reconfigured even for small changes in the interplanetary magnetic field and the solar wind (SW) dynamic pressure. Different configurations are due to occurrence of different structures in the SW. Among them, high speed streams from coronal holes, magnetic clouds, and noncompressive density enhancement have been analyzed to better characterize the Hermean conditions, which might be expected during the ongoing BepiColombo mission. Helios 1 and 2 mission data collected between 0.29 and 0.47 AU have been used to perform a statistical analysis of these SW structures. The numerical results reported in the paper, as well as the probability densities displayed in the maps, give more precise indications when associated to a rigorous SW structures selection. The occurrence rate along solar cycle together with the average features of each class of SW structures are useful information for Space Weather topics. Results from the same analysis performed at 1 AU have been used to further verification of the radial behavior of the SW parameters.

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