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Abstract The Earth’s radiation belts are maintained by a number of acceleration, loss and transport mechanisms, and the electron fluxes at any given time are highly variable. Microbursts, which are rapid (sub-second) bursts of energetic electrons entering the atmosphere from the magnetosphere, are one of the key loss mechanisms controlling radiation belt fluxes. Such rapid bursts are typically observed from the outer radiation belt and driven by interactions with whistler mode chorus waves, but they can also occur in the inner belt and slot region, driven by lightning-generated whistlers. This lightning-induced electron precipitation is typically observed at 10s–100s keV, but here we present direct observations of this phenomenon at MeV energies. This unveils a coupling between near-Earth processes, such as lightning, and radiation belt processes, such as relativistic electron microbursts, bridging the gap between Earth weather and space weather. 

Abstract To gain deeper insights into radiation belt loss into the atmosphere, a statistical study of MeV electron precipitation during radiation belt dropout events is undertaken. During these events, electron intensities often drop by an order of magnitude or more within just a few hours. For this study, dropouts are defined as a decrease by at least a factor of five in less than 8 hours. Van Allen probe measurements are employed to identify dropouts across various parameters, complemented by precipitation data from the CALorimetric Electron Telescope instrument on the International Space Station. A temporal analysis unveils a notable increase in precipitation occurrence and intensity during dropout onset, correlating with the decline of SYM‐H, the north‐south component of the interplanetary magnetic field, and the peak of the solar wind dynamic pressure. Moreover, dropout occurrences show correlations with the solar cycle, exhibiting maxima at the spring and autumn equinoxes. This increase during equinoxes reflects the correlation between equinoxes and the SYM‐H index, which itself exhibits a correlation with precipitation during dropouts. Spatial analysis reveals that dropouts with precipitation penetrate into lower L‐star regions, mostly reaching L‐star <4, while most dropouts without precipitation don't penetrate deeper than L‐star 5. This is consistent with the larger average dimensions of dropouts associated with precipitation. During dropouts, precipitation is predominantly observed in the dusk‐midnight sector, coinciding with the most intense precipitation events. The results of this study provide insight into the contribution of precipitation to radiation belt dropouts by deciphering when and where precipitation occurred. 

Abstract Over 1500 balloons are launched every day, from every continent on Earth, to provide forecasting of tropospheric weather. Similar balloons, which can fly to the edge of space (>30 km), can be used for other science projects. Professional scientists, military users, commercial organisations, and interested amateurs, all fly payloads that provide a relatively low-cost means to reach the upper atmosphere. Weather ballooning is perfectly suited to student education and has been carried out for decades by groups of school, college, and university students. Here we report on one such a project. During March/April 2023 a series of balloons were launched from Sodankylä, Finland, in order to study the particle and radiation environment, along with ozone, in the stratosphere. Inexpensive off-the-shelf Geiger-counters were part of a payload flown to investigate how the radiation environment changed over time. Balloon payloads can be tracked with simple and inexpensive radio receivers. Similar projects to the one outlined here should be possible for any school, college, or university that has a reasonably well-equipped workshop, a group of interested and capable students, and a desire to investigate and learn something new about the planet we live on.