Prediction of radiation belts electron fluxes at a Low Earth Orbit using neural networks with PROBA-V/EPT data

We introduce for the first time the PROBA-V/EPT electron flux data to train a deep learning data-driven model with the purpose of investigating the Earth’s radiation belts dynamics. The Long-Short Term Memory Neural Network is employed to predict the electron fluxes between 1 and 8 Earth Radius (RE) along a Low Earth Orbit. Different combinations of time series inputs involving Solar Wind and geomagnetic data are tested, based on previous knowledge of their impact onto the high energy radiation fluxes. Two Energetic Particle Telescope energy channels feed the learning procedure for nonrelativistic (0.5–0.6 MeV) and relativistic (1.0–2.4 MeV) electron fluxes. A good performance of the model employing different time resolutions from hours to days is demonstrated with a correlation of more than 0.9 between the predicted and out-of-sample fluxes, and a prediction efficiency that can attain between 0.6 and 0.9 depending on the L range. The analysis of different input parameters and time resolutions allows to construct the best data set structure and improve the model to identify relevant effects such as dropouts, flux increase and recovery features

The role of plasmasphere in the formation of electron heat fluxes

Plasmasphere plays an important role in the magnetospheric physics, defining many important inputs to the ionosphere from the middle to the auroral latitudes. Among them are electron thermal heat fluxes resulting from the Coulomb interaction of superthermal electrons (SE) and cold plasmaspheric electrons. These fluxes define the electron temperature at the upper ionospheric altitudes and are the input to the global ionospheric modeling networks. As was previously found from the calculation of lower energy SE and thermal heat fluxes, the knowledge of field-aligned cold plasma distribution in the plasmasphere is a very sensitive parameter that introduces the most uncertainties in the calculation of these values. To verify the previously used SuperThermal Electron Transport code assumptions regarding plasmaspheric field-aligned density structure ∼[B(s)/Bo]a, we used the latest version of 3D plasmaspheric model developed by Pierrard, Botek, and Darrouzet (2021, https://doi.org/10.3389/fspas.2021.681401). Such an assumption is found to be very reasonable in the calculations of electron thermal heat fluxes entering upper ionospheric altitudes and the associated electron temperature formation for the two selected dayside and nightside electron precipitation events driven by whistler-mode wave activity

Proton flux variations during solar energetic particle events, minimum and maximum solar activity, and splitting of the proton belt in the South Atlantic Anomaly

The analysis of the proton flux variations observed by the Energetic Particle Telescope (EPT) at energies >9.5 MeV from the launch of PROBA-V satellite on 7 May 2013 up to October 2022 shows an anti-correlation between the proton fluxes and the solar phase. At solar minimum, the fluxes are higher at low L corresponding to the northern border of the South Atlantic Anomaly (SAA). This solar cycle modulation of the inner belt is mainly due to losses by increased atmospheric interactions during solar maximum. Strong Solar Energetic Particle (SEP) events, like in January 2014, June 2015, and September 2017, inject energetic protons at high latitudes, but not in the inner belt where protons are trapped at long term at low L. Nevertheless, big geomagnetic storms, including those following SEP a few days after, can cause losses of protons at the outer border of the proton belt, due to magnetic field perturbations. A double peak in the proton belt is observed during long period of measurements only for the EPT channel of 9.5–13 MeV. The narrow gap between the two peaks in the inner belt is located around L = 2. This resembles to a splitting of the proton belt, separating the SAA into two different parts, North and South. The high-resolution measurements of PROBA-V/EPT allow the observation of small-scale structures that brings new elements to the understanding of the different source and loss mechanisms acting on the proton radiation belt at LEO

FARWEST: Efficient Computation of Wave-Particle Interactions for a Dynamic Description of the Electron Radiation Belt Diffusion

In this paper, we present a new method to compute rapidly, wave particle interaction induced pitch angle and momentum diffusion coefficients. Those terms are normally obtained by the numerical solving of equations based on the quasi-linear theory. However, this bulk resolution leads to a high computational cost, preventing the integration of plasma density and VLF waves nowcasts and forecasts. Therefore, and in the context of the SAFESPACE project (H2020), we implemented a new wave particle interaction code called FARWEST (FAst Radiation diffusion with Waves ESTimator), with an efficient interpolation based method. The proposed implementation was validated against reference results obtained by WAPI, ONERA's wave particle interaction legacy code, with a substantial reduction of the computing time while conserving the physical accuracy of the generated coefficients. The FARWEST code is later used to measure the impact of a time-dependent plasma density distribution (numerically computed by BIRA's plasmaspheric model SPM) on the coefficients and on the representation of the electron flux map by Salammbô, ONERA's radiation belt code

BIOSPHERE measurement campaign from January 2024 to March 2024 and in May 2024: Effects of the solar events on the radiation belts, UV radiation and ozone in the atmosphere

In this work, we analyzed simultaneous observations of solar particles and solar electromagnetic ultraviolet (UV) radiation during solar events from January 2024 to May 2024. Measurement campaigns to study the effects of space radiation on the terrestrial atmosphere were conducted in the framework of the project BIOSPHERE. We show the results of the campaign in Brussels from 1 January 2024 to 31 March 2024, during which several solar energetic particle (SEP) events were observed by the spacecraft GOES and OMNI, together with two big geomagnetic storms in March 2024 and May 2024 associated with solar eruptions. The last two events combine the arrival of a SEP event with a geomagnetic storm. On 11 May 2024, the biggest geomagnetic storm for the last 20 years was observed. These events enabled us to identify effects due to UV, solar particles, and geomagnetic storms. The impact of these events on the terrestrial radiation belts, illustrated by satellite observations like PROBA-V/EPT and on the atmospheric ozone using AURA/MLS is demonstrated. For the measurement campaign, muon and neutron monitors showed a Forbush decrease only during the geomagnetic storm at the end of March 2024 and in May 2024. Complemented by a simulation of radiation effects on the ionization rate of the atmosphere as a function of the altitude, the extensive range of different observations available during this measurement campaign demonstrated that SEP and geomagnetic storms due to solar eruptions had very different effects on the terrestrial atmosphere. The geomagnetic storms mainly modified the energetic electrons trapped in the space environment of the Earth and affected the ionization of the atmosphere above 60 km. They also modified the cosmic ray injections, mainly at high latitudes, creating Forbush decrease for the most intense ones. SEP events injected energetic protons in the atmosphere that could penetrate deeper in the atmosphere because they had more energy than the electrons. They could impact ozone, mainly at high altitude in the thermosphere. Solar activity variation associated with the rotation of the solar active regions in 27 days modulated UV. The measurements of these electromagnetic and particle radiations are crucial because they have important health implications

Integrating plasmasphere, ionosphere and thermosphere observations and models into a standardised open access research environment: The PITHIA-NRF international project

The PITHIA-NRF project “Plasmasphere Ionosphere Thermosphere Integrated Research Environment and Access services: a Network of Research Facilities” aims at building a European distributed network that integrates observations from space and ground, data processing tools and models to support scientific research on the Plasmasphere-Ionosphere-Thermosphere system. PITHIA-NRF is designed to provide formalised open access to experimental facilities, data and models, standardised data products, and training services. Participating organisations that operate these facilities, formed twelve nodes in eleven European countries. These nodes work on optimising their observing facilities and offer trans-national access to scientists and engineers. The PITHIA-NRF e-Science Centre is a core element of the project. Its design and evolution are controlled by a systematic ontology which governs the collection of scientific observations and research models, jointly termed data collections, which are registered with the e-Science Centre. Several tens of data collections are being registered. Data collection registrations adhere to FAIR principles and transparent quality measures to a large extent. The e-Science Centre facilitates the execution of research projects proposed by researchers from inside and outside the PITHIA-NRF consortium which require trans-national access to and understanding of data collections (observations and models) residing at one or several PITHIA-NRF nodes. Upon completion of the project a comprehensive collection of observations and models will have been gathered by the e-Science Centre for the benefit of efficient scientific research which relies on Europe-wide collaboration

Fingerprints for Structural Defects in Poly(thienylene vinylene) (PTV): A Joint Theoretical–Experimental NMR Study on Model Molecules

In the field of plastic electronics, low band gap conjugated polymers like poly(thienylene vinylene) (PTV) and its derivatives are a promising class of materials that can be obtained with high molecular weight via the so-called dithiocarbamate precursor route. We have performed a joint experimental- theoretical study of the full NMR chemical shift assignment in a series of thiophene-based model compounds, which aims at (i) benchmarking the quantum-chemical calculations against experiments, (ii) identifying the signature of possible structural defects that can appear during the polymerization of PTV's, namely head-to-head and tail-to-tail defects, and (iii) defining a criterion regarding regioregularity