Session ST1.10

[Programme]

ST1.10 | Energetic Particles: From the Sun to their Terrestrial & Planetary Impacts

Energetic Particles: From the Sun to their Terrestrial & Planetary Impacts

Co-organized by AS4/PS2

Convener: Simon Thomas | Co-conveners: Nina Dresing, Graeme MarltonECSECS, Ross PallisterECSECS

Orals

| Thu, 27 Apr, 14:00–15:45 (CEST)

Room L1

Posters on site

| Attendance Wed, 26 Apr, 14:00–15:45 (CEST)

Hall X4

Posters virtual

| Attendance Wed, 26 Apr, 14:00–15:45 (CEST)

vHall ST/PS

The heliosphere is permeated with energetic particles of different compositions, energy spectra and origins. Two major populations of these particles are galactic cosmic rays (GCRs), which originate from outside of the heliosphere and are constantly detected at Earth, and solar energetic particles (SEPs) which are accelerated at/near the Sun during solar flares or by shock fronts associated with the transit of coronal mass ejections. Enhancements in energetic particle fluxes at Earth pose a hazard to humans and technology in space and at high altitudes. Within the magnetosphere, energetic particles are present in the radiation belts, and particle precipitation is responsible for the aurora and for hazards to satellites. Energetic particles have also been shown to cause changes is the chemistry of the middle and upper atmosphere, thermodynamic effects in the upper troposphere and lower stratosphere region, and can influence components of the global electric circuit. This session will aim to address the transport of energetic particles through the heliosphere, their detection at Earth and the effects they have on the terrestrial atmosphere when they arrive. It will bring together scientists from several fields of research in what is now very much an interdisciplinary area. The session will allow sharing of expertise amongst international researchers as well as showcase the recent advances being made in this field, which demonstrate the importance of the study of these energetic particle populations.

Orals: Thu, 27 Apr | Room L1

Chairpersons: Simon Thomas, Ross Pallister, Graeme Marlton

14:00–14:05

5-minute convener introduction

14:05–14:25

EGU23-5292

ST1.10

solicited

Highlight

Virtual presentation

The Impact of Solar Energetic Particles at Mars’ radiation environment: A synergistic approach combining measurements and Modeling efforts

Jingnan Guo

Radiation is one of the most important risks to deep space exploration programs such as manned missions to the Moon and Mars. In preparation for such programs, it requires a thorough understanding of interplanetary space weather conditions and a timely forecast of their potential effects as a baseline for the development of mitigation strategies.

Radiation damage in space comes mainly from two sources, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). In particular, intense SEP events could result in very high doses in a short time period that may exceed the threshold to induce deterministic radiation effects and to result in severe damages to humans and equipment leading to the failure of the entire mission. SEP events with radiation hazards, despite of being rather infrequent and sporadic, are however very difficult to forecast and remain as a major challenge for space weather studies in preparation for future deep space and Mars missions.

Specifically speaking, the SEP radiation reaching an astronaut on a Mars may be completely different from of that detected at (or predicted for) Earth’s vicinity, including the SEP onset time, spectra evolution, radiation intensity etc. This is due to (1) the different location of Mars and connectivity to the acceleration source which allow it to have difference access to the SEP population, and (2) the different planetary environment which modifies the energy and composition of the particles due to the interactions of primary particles with the atmosphere/regolith and the generation of secondaries. The synergistic analysis and modeling of these two processes are particularly important to understand and eventually forecast SEPs and their radiation effects on Mars in preparation for mitigating their potential hazardous effects. We also emphasize the utmost importance of utilizing multi-spacecraft particle measurements at Mars and also other heliospheric locations to better understand such extreme events and their radiation effects for future deep space explorers.

How to cite: Guo, J.: The Impact of Solar Energetic Particles at Mars’ radiation environment: A synergistic approach combining measurements and Modeling efforts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5292, https://doi.org/10.5194/egusphere-egu23-5292, 2023.

14:25–14:35

EGU23-2518

ST1.10

ECS

Virtual presentation

Solar activity relations in energetic electron events measured by the MESSENGER mission

Laura Rodríguez-García, Laura Balmaceda, Raúl Gómez-Herrero, Athanasios Kouloumvakos, Nina Dresing, David Lario, Yannis Zouganelis, Annamaria Fedeli, Francisco Espinosa Lara, Ignacio Cernuda, George Ho, Robert Wimmer-Schweingruber, and Javier Rodríguez-Pacheco

We perform a statistical study of the relations between the properties of solar energetic electron (SEE) events measured by the MESSENGER mission from 2010 to 2015 and the parameters of the respective parent solar activity phenomena to identify the potential correlations between them. During the time of analysis MESSENGER heliocentric distance varied between 0.31 and 0.47 au.

The main conclusion of the study is as follows. For this particular sample of events, with a majority of SEE events being widespread in heliolongitude and displaying relativistic electron intensity enhancements, a shock-related acceleration mechanism might be relevant in the acceleration of near-relativistic electrons. This conclusion is mainly based on three results. (1) The high and significant correlation found between the SEE peak intensities and the shock speed. (2) The ∼4 orders of magnitude in the SEE peak intensities for the same CME-driven shock speed that might be related to the presence of supra-thermal seed population that made local shock acceleration more efficient. (3) The asymmetry to the east of the range of connection angles (CAs) for which the SEE events present higher peak intensities and higher correlations with the solar activity, which might be related to the evolution of the magnetic field connection to the shock front. We note that the CA is defined as the angular distance between the footpoint of the magnetic field connecting to the spacecraft and the longitude of the source region.

How to cite: Rodríguez-García, L., Balmaceda, L., Gómez-Herrero, R., Kouloumvakos, A., Dresing, N., Lario, D., Zouganelis, Y., Fedeli, A., Espinosa Lara, F., Cernuda, I., Ho, G., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Solar activity relations in energetic electron events measured by the MESSENGER mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2518, https://doi.org/10.5194/egusphere-egu23-2518, 2023.

14:35–14:45

EGU23-9582

ST1.10

ECS

On-site presentation

Flare-accelerated electrons and their traces in the solar corona observed by space- and ground-based instruments

Malte Bröse and Christian Vocks

14:45–14:55

EGU23-14711

ST1.10

On-site presentation

Monitoring of Solar Energetic Particles and Cosmic Rays with the RADEM instrument onboard the ESA JUICE mission

Wojtek Hajdas, Patricia Goncalves, Marco Pinto, Andre Galli, and Olivier Witasse

The main goal of the radiation monitor RADEM flying onboard the ESA JUICE mission is to provide continuous information on particle fluxes and their energy spectra. The monitor measures electrons up to 40 MeV and protons up to 250 MeV. Such a range of energies detected by RADEM enables covering the most hazardous regimes in terms of radiation damage. Spectroscopic information on particle energies is provided using eight quasi-logarithmic energy bins. RADEM has also a dedicated heavy-ion detector designed to measure a variety of heavy ion species with their LET between 0.1 and 10 MeV/cm/mg^-1. Moreover, the monitor contains an additional detector sensitive to the direction of incoming radiation. It expands the instrument's angular coverage up to 35% of the sky. Apart from its spectroscopic and angular distribution functions, RADEM will continuously provide values of the radiation dose deposited by each particle species. Its telemetry data will be stored in the data center for the JUICE mission operated by the European Space Astronomy Centre. After preprocessing the higher-level data will become available to the JUICE scientific team. RADEM will be switched on shortly after the JUICE launch planned for April 2023 and after a short commissioning phase will start its nominal operation. Apart from regular and short tuning and calibration periods, it will remain operating for the rest of the mission i.e. almost 10 years. While its primary purpose is to monitor the mission levels for safety concerns of the spacecraft and its scientific payload, its measurements open a unique opportunity for conducting real-time, continuous observations during its full cruise to Jupiter. RADEM will study all aspects of the radiation phenomena characteristic to the Earth and Solar System. Correlations with other instruments will allow for advanced observations of particle event propagation and a better understanding of processes related to the dynamics of particle environments including their links with solar activity and magnetic fields across the solar system. In particular, during its first two years of the cruise to Jupiter, RADEM will precisely map the radiation environment between Venus and Mars, providing uninterrupted time-resolved spectroscopy and dosimetry data from Solar Energetic Particles and Cosmic Rays.

How to cite: Hajdas, W., Goncalves, P., Pinto, M., Galli, A., and Witasse, O.: Monitoring of Solar Energetic Particles and Cosmic Rays with the RADEM instrument onboard the ESA JUICE mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14711, https://doi.org/10.5194/egusphere-egu23-14711, 2023.

14:55–15:05

EGU23-7905

ST1.10

ECS

Highlight

On-site presentation

Development of an In-Progress Forecasting Model to Forecast Radiation Dose Rates Once a Ground-Level Enchancement has Begun

Chris Davis, Charlotte Waterfall, Fan Lei, Silvia Dalla, Keith Ryden, Ben Clewer, and Clive Dyer

During major solar energetic particle events, radiation dose rates in Earth's atmosphere at aviation altitudes can increase by orders of magnitude relative to dose rates during quiet times in events known as Ground-Level Enhancements (GLEs). In the case of events of a scale such that they occur once every few decades, radiation dose rates could become high enough that they pose a threat to aircraft crew and electronics. It is not currently possible to predict when such an event will occur, and existing software systems are only capable of nowcasting the current atmospheric radiation dose rates using real-time data sources. However, while it is not possible to forecast when a major event will occur, it may be possible to generate forecasts for radiation dose rates once an event has been registered to have begun. The ability to provide forecasts for dose rates once a GLE has started would be vital for airlines and for pilots in any future where aircraft might be rerouted to avoid regions of high radiation, as pilots need to be able to know not just their current radiation dose rates but radiation dose rates at possible locations where their plane might be in say half an hour's time. We report on the development of a software system to do this. This 'in-progress' radiation dose rate forecasting system will be developed by integrating the FOrecasting Relativistic particles during GLE Events (FORGE) system being developed at the University of Central Lancashire with an anisotropic extension to the Models for Atmospheric Ionising Radiation Effects+ (MAIRE+) system being developed at the University of Surrey. We report on the development of both of these systems and their integration.

How to cite: Davis, C., Waterfall, C., Lei, F., Dalla, S., Ryden, K., Clewer, B., and Dyer, C.: Development of an In-Progress Forecasting Model to Forecast Radiation Dose Rates Once a Ground-Level Enchancement has Begun, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7905, https://doi.org/10.5194/egusphere-egu23-7905, 2023.

15:05–15:15

EGU23-8936

ST1.10

ECS

On-site presentation

Particle Energisation in a 3D Collapsing Magnetic Trap Model With a Braking Jet

Kate Mowbray and Thomas Neukirch

Investigating the motion of charged particles in time- and space-dependent electromagnetic fields is central to many areas of space and astrophysical plasmas. Here we present results of studying the energy changes of particle orbits that are trapped in inhomogeneous and time-dependent magnetic fields with rapidly shortening field lines. These so-called collapsing magnetic trap (CMT) models can be useful to better understand the particle energisation processes occurring below the reconnection region in a solar flare. Braking jets may be associated with magnetic reconnection, for example when a sunward flow slows down as it approaches a stronger region of magnetic field. We generalise a 2D CMT model with braking jet (Borissov et al., 2016) to three dimensions and investigate the dynamics of particles in this 3D CMT model. The resulting particle orbits show a sensitive dependence of particle energies on the initial conditions of orbits, with initial pitch angles playing a particularly important role. This sensitive dependence relates to the time evolution of trapping regions that develop in the braking jet region of the CMT, ensuring that some orbits spend a significant time in the loop legs of field lines, whilst others escape these regions for the duration of the simulation. These loop leg trapped particle orbits see significantly lower energy gains than those orbits that repeatedly pass the loop top, with some of these particles even losing energy. This gives us greater insight into the importance of the curvature of collapsing loop tops for the Fermi acceleration mechanism acting on the particles.

Borissov A. et al., Solar Physics 291, Issue 5, 1385

How to cite: Mowbray, K. and Neukirch, T.: Particle Energisation in a 3D Collapsing Magnetic Trap Model With a Braking Jet , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8936, https://doi.org/10.5194/egusphere-egu23-8936, 2023.

15:15–15:25

EGU23-7

ST1.10

ECS

On-site presentation

Modeling the 2020 November 29 solar energetic particle event using EUHFORIA and iPATH models

Zheyi Ding, Nicolas Wijsen, Gang Li, and Stefaan Poedts

We present the implementation of a coupling between EUropean Heliospheric FORcasting Information Asset (EUHFORIA) and improved Particle Acceleration and Transport in the Heliosphere (iPATH) models. In this work, we simulate the widespread solar energetic particle (SEP) event of 2020 November 29 and compare the simulated time-intensity profiles with measurements at Parker Solar Probe (PSP), the Solar Terrestrial Relations Observatory (STEREO)-A, SOlar and Heliospheric Observatory (SOHO), and Solar Orbiter (SolO). We examined the temporal evolution of shock parameters and particle fluxes during this event and we find that adopting a realistic solar wind background can significantly impact the expansion of the shock and, consequently, the shock parameters. Time-intensity profiles with an energetic storm particle event at PSP are well reproduced from the simulations. In addition, the simulated and observed time-intensity profiles of protons show a similar two-phase enhancement at STA. These results illustrate that modeling a shock using a realistic solar wind is crucial in determining the characteristics of SEP events. The decay phase of the modeled time-intensity profiles at Earth is in good agreement with the observations, indicating the importance of perpendicular diffusion in widespread SEP events. Taking into account the possible large curved magnetic field line connecting to SolO, the modeled time-intensity profiles show a good agreement with the observation. We suggest that the broadly distorted magnetic field lines, which are due to a stream interaction region, may be a key factor in understanding the observed SEPs at SolO.

How to cite: Ding, Z., Wijsen, N., Li, G., and Poedts, S.: Modeling the 2020 November 29 solar energetic particle event using EUHFORIA and iPATH models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7, https://doi.org/10.5194/egusphere-egu23-7, 2023.

15:25–15:35

EGU23-16177

ST1.10

Highlight

On-site presentation

Risks of space radiation exposure to exploration astronauts: limitations in predictions based on the ground experiments and possible solutions

Salman Khaksarighiri, Robert Wimmer-Schweingruber, Jingnan Guo, Cary Zeitlin, Thomas Berger, and Daniel Matthiä

Future expeditions into interplanetary space, and in particular to the Moon and Mars, will expose astronauts to very high levels of cosmic radiation, which are known due to years of research and instruments that have been sent to space. It is, however, a limitation in understanding the risks of this radiation for the human body due to difficulties in simulating the complex space environment on Earth or complex human phantom and the inability to extrapolate human clinical outcomes based on animal models or simulation results.
As human spaceflight continues on its path to success, we need to develop appropriate and effective mitigation strategies for future missions to improve our understanding of the space radiation risk by identifying the constraints of radiation research on the Earth and finding possible solutions based on the existing technologies to be closer to the reality as much as possible and better understand human physiology in space.
As part of this paper, we have identified several factors that hinder our understanding of radiation risks for human crews and have identified ways to cope with these restrictions for a better understanding and preparation for human spaceflights in the future.

How to cite: Khaksarighiri, S., Wimmer-Schweingruber, R., Guo, J., Zeitlin, C., Berger, T., and Matthiä, D.: Risks of space radiation exposure to exploration astronauts: limitations in predictions based on the ground experiments and possible solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16177, https://doi.org/10.5194/egusphere-egu23-16177, 2023.

15:35–15:45

EGU23-12330

ST1.10

ECS

Highlight

On-site presentation

When are energetic electrons producing NO directly in the upper stratosphere?

Josephine Salice, Hilde Nesse, Noora Partamies, Emilia Kilpua, Andrew Kavanagh, Eldho Babu, and Christine Smith-Johnsen

Compositional NOx changes caused by energetic electron precipitation (EEP) at a specific altitude are called the EEP direct effect. Changes co-dependent on vertical transport are referred to as the EEP indirect effect. The relative importance of EEP’s direct and indirect effect on NO and its subsequent impact on ozone and dynamic changes remain unresolved. The challenges are partly due to inadequate particle measurement and the relative scarcity of NO observations over the polar MLT region. Moreover, lower production rates in the mesosphere make it challenging to determine EEP’s direct impact on NO since small in-situ enhancements cannot be easily distinguished from the descending NO-rich air masses in the winter hemisphere. In this study, the uncertainty of the EEP observations is bypassed by exclusively identifying events applying NO-observations from the SOFIE instrument on board the AIM satellite. SOFIE daily averaged data from 2007 to 2014 is used to create a climatology based on the mean of the lower half of the data (lower 50 percentile mean). A direct EEP-produced NO-event at 90 km (“90km-event”) is identified when the NO density surpasses the climatology by 100%. If the NO density exceeds 25% above the climatology at 80, 70, 60, and 50 km, the event qualifies as a “50km-event”. By contrasting the 90km and 50km events, the characteristics of the solar wind and geomagnetic indices, as well as observed electron fluxes from POES, are studied. The goal is to unravel when EEP can produce NO directly in the upper stratosphere. The result will contribute to developing a parameterization of EEP from the radiation belt that includes both the direct and indirect impact of EEP to decipher the total EEP effect on the ozone and atmospheric dynamics.

How to cite: Salice, J., Nesse, H., Partamies, N., Kilpua, E., Kavanagh, A., Babu, E., and Smith-Johnsen, C.: When are energetic electrons producing NO directly in the upper stratosphere?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12330, https://doi.org/10.5194/egusphere-egu23-12330, 2023.

Posters on site: Wed, 26 Apr, 14:00–15:45 | Hall X4

Chairperson: Simon Thomas

X4.287

EGU23-15621

ST1.10

ECS

The effect of magnetic reconnection on ICME-related GCR modulation

Emma Davies, Camilla Scolini, Réka Winslow, and Andrew Jordan

The large-scale magnetic structure of interplanetary coronal mass ejections (ICMEs) has been shown to cause temporary decreases in the galactic cosmic ray (GCR) flux measured in situ by spacecraft, known as Forbush decreases (Fds). In some ICMEs, the magnetic ejecta exhibits a magnetic flux rope structure; the strong magnetic field strength and closed field line geometry of such ICME magnetic flux ropes has been proposed to act as a shield to GCR transport. However, as ICMEs propagate, they undergo many processes including interactions and magnetic reconnection with the interplanetary magnetic field (IMF) in large-scale solar wind structures and other solar transients. In this study, we investigate how ICME interaction and reconnection during propagation affects Fd size, shape, and duration. We hypothesize that the alteration of the ICME magnetic topology due to reconnection (specifically the opening of the closed magnetic field configuration in the ICME flux rope) will have a strong effect on the ICME’s ability to modulate GCRs. To test this hypothesis, we compare the Fds of ICMEs that likely underwent reconnection during propagation with ones that likely did not.

To this end, we identify ICMEs that exhibited open magnetic field line topologies (i.e., ones that likely underwent reconnection) and we compare their effects on GCRs with those of ICMEs that exhibited closed topologies (both ends connected to the Sun). We use magnetic field, solar wind plasma, and suprathermal electron pitch angle distribution data at ACE and Wind to select the ICMEs. Furthermore, we use data by the SOPO and McMurdo neutron monitors at Earth to investigate how the magnetic structure of the ICME ejecta modulates the GCRs by comparing the resulting Fds for the selected ICMEs. The results of our study yield new insights into how the modulation of GCRs is affected by ICME evolution and interaction during propagation and whether reconnection of the ICME flux rope weakens its modulation of GCRs.

How to cite: Davies, E., Scolini, C., Winslow, R., and Jordan, A.: The effect of magnetic reconnection on ICME-related GCR modulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15621, https://doi.org/10.5194/egusphere-egu23-15621, 2023.

X4.288

EGU23-10509

ST1.10

ECS

Radial Variation of Suprathermal Particles Associated with Corotating Interaction Regions

Robert Allen, George Ho, Glenn Mason, Athanasios Kouloumvakos, Robert Wimmer-Schweingruber, and Javier Rodríguez-Pacheco

The first three years of Solar Orbiter operations have enabled robust sampling of the intensity and composition of suprathermal particles within the inner heliosphere. This includes a multitude of observations of suprathermal ions associated with Corotating Interaction Regions (CIRs), with corresponding observations at 1 au with measurements from the Ultra-Low-Energy Isotope Spectrometer (ULEIS) on the Advanced Composition Explorer (ACE) mission and the Suprathermal Ion Telescope (SIT) on the Solar-Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft. Comparing observations between these spacecraft allows for a statistical view of the radial variations of CIR-associated suprathermal particles by composition in the inner heliosphere, allowing for greater insight into energetic particle transport within the inner heliosphere. This study expands on early results from Solar Orbiter and ACE to now encompass the first three years of Solar Orbiter operations, as well as include STEREO-A measurements. Comparisons to historical studies of CIR-associated energetic protons are also expanded in the survey of CIR-associated suprathermal particles from Solar Orbiter, ACE, and STEREO-A.

How to cite: Allen, R., Ho, G., Mason, G., Kouloumvakos, A., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Radial Variation of Suprathermal Particles Associated with Corotating Interaction Regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10509, https://doi.org/10.5194/egusphere-egu23-10509, 2023.

X4.289

EGU23-9443

ST1.10

ECS

Simulations of SEP events with the novel PARADISE+ICARUS model

(withdrawn)

Edin Husidic, Nicolas Wijsen, Tinatin Baratashvili, Stefaan Poedts, and Rami Vainio

X4.290

EGU23-4398

ST1.10

ECS

Analysis of the Energetic Storm Particle events of 6-7 September 2017

Federica Chiappetta, Monica Laurenza, Fabio Lepreti, Simone Benella, and Giuseppe Consolini

Most of the energetic particles observed in the heliosphere are accelerated from a few keV up to MeV by shock fronts which are associated with the transit of coronal mass ejections (CMEs). The study of energetic storm particle events (ESP) can be very helpful for the investigation of the acceleration processes of particles at the shocks. We considered two ESP events occurring 6-7 September, 2017. The data used to study kinetic energy spectra are proton ﬂux enhancements provided by WIND and ACE spacecraft that are both at the Lagrangian point L1, close to 1 AU along the Sun-Earth direction. The energy ranges are from 70 keV to 70 MeV and from 40 keV to 4.8 MeV, respectively. In order to broaden the range of the analyzed energies, we combine these data with the proton fluxes from SoHO spacecraft, also located at L1, which detects particles with energies from 1.3 MeV to 130 MeV. We used the Weibull functional form, the double power law and the Ellison-Ramaty form to fit the observed spectra. The implications of the obtained results for particle acceleration are discussed, taking also into account the properties of the shocks and of the magnetic turbulence in their surroundings.

“This research has been carried out in the framework of the CAESAR project, supported by the Italian Space Agency and the National Institute of Astrophysics through the ASI-INAF n. 2020-35-HH.0 agreement for the development of the ASPIS prototype of scientific data centre for Space Weather.”

How to cite: Chiappetta, F., Laurenza, M., Lepreti, F., Benella, S., and Consolini, G.: Analysis of the Energetic Storm Particle events of 6-7 September 2017, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4398, https://doi.org/10.5194/egusphere-egu23-4398, 2023.

X4.291

EGU23-15517

ST1.10

Proton energy spectra of energetic storm particle events and their relation with magnetic turbulence and intermittency nearby interplanetary shocks

Fabio Lepreti, Federica Chiappetta, Monica Laurenza, Simone Benella, and Giuseppe Consolini

Shock waves propagating in the interplanetary space are efficient sources of energetic particles. In situ spacecraft observations, especially particle fluxes which can be used to obtain energy spectra, provide very useful data for the investigation of the acceleration mechanisms occurring at shocks. In this work we analyse the kinetic energy spectra of several proton flux enhancements associated with energetic storm particle (ESP) events observed by various spacecraft. ESP events occurring both in association with and in absence of Solar Energetic Particles (SEPs) are considered. Moreover, ESP events associated both with quasi-perpendicular and quasi parallel shocks are investigated. Different functional forms (i.e. Weibull function, double power law, and Ellison-Ramaty) are used to fit the observed spectra and the obtained results are discussed in relation to the shock properties and to the magnetic turbulence and intermittency in the upstream and downstream regions. More specifically, the properties of magnetic turbulence and intermittency are analysed by calculating power spectral densities and structure functions of the fluctuations of the magnetic field components and the implications for particle acceleration are examined.

This research has been carried out in the framework of the CAESAR project, supported by the Italian Space Agency and the National Institute of Astrophysics through the ASI-INAF n. 2020-35-HH.0 agreement for the development of the ASPIS prototype of scientific data centre for Space Weather.

How to cite: Lepreti, F., Chiappetta, F., Laurenza, M., Benella, S., and Consolini, G.: Proton energy spectra of energetic storm particle events and their relation with magnetic turbulence and intermittency nearby interplanetary shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15517, https://doi.org/10.5194/egusphere-egu23-15517, 2023.

X4.292

EGU23-16136

ST1.10

Energetic Electron Precipitation during Slot Region Filling Events

Hilde Nesse, Eldho Midhun Babu, Josephine Salice, and Bernd Funke

The region separating the inner and outer radiation belt, typically devoid of energetic electrons, is termed the slot region. The outer edge of the slot region marks the equatorward edge of the energetic electron precipitation (EEP) originating from the outer radiation belt. Its varying location is strongly linked to the plasmasphere and geomagnetic activity. As such, geomagnetic indices are used to estimate the equatorward extent of the EEP region. There are, however, numerous reports where the energetic electrons cross these boundaries and fill the slot region, during which energetic electrons that can precipitate into the atmosphere long after the geomagnetic activity subsides. This is a missing source of energy input in current EEP estimates based on geomagnetic indices.

This study explores the occurrence rate, reformation, local time dependence, and energy deposition of slot region filling events. Medium energy electron measurements from the NOAA/POES over a full solar cycle from 2004 to 2014 are applied. We combine observations from the MEPED 0° and 90° detectors together with theory of pitch angle diffusion by wave-particle interaction to estimate the precipitating fluxes. To explore the energy dependent characteristics, each of the MEPED energy channels, > 43, >114, and >292 keV are evaluated independently. Finally, we investigate the potential EEP impact on the NO density utilizing seven years of Envisat MIPAS NO observations from 2005 to 2011.

How to cite: Nesse, H., Babu, E. M., Salice, J., and Funke, B.: Energetic Electron Precipitation during Slot Region Filling Events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16136, https://doi.org/10.5194/egusphere-egu23-16136, 2023.

X4.293

EGU23-7171

ST1.10

Modelling of atmospheric transport of SEP-induced cosmogenic 10Be using CCM SOCOL-AER2-BE

Kseniia Golubenko, Eugene Rozanov, Gennady Kovaltsov, Mélanie Baroni, and Ilya Usoskin

¹⁰Be is a cosmogenic isotope continuously produced in the Earth’s atmosphere by galactic cosmic rays (GCRs) and sporadically by solar energetic particles (SEPs). The long-living isotope, as measured in polar ice cores, typically with an annual resolution, serves as a proxy for long-term cosmic-ray variability, whose signal can, however, be distorted by atmospheric transport and deposition that need to be properly modelled. Atmospheric transport of ¹⁰Be depends on production, atmospheric circulation, and local orography. For an accurate physical description of the isotope's transport and deposition, we use the chemical climate model (CCM) SOCOL-AER2-BE. In combination with the production model CRAC, our model was verified using real measurements of beryllium in ice cores for Antarctic and Greenland locations. The model results agree with the measurements at the absolute level, implying that the production, decay, and lateral deposition are correctly reproduced. However, the exact time variability is not always well reproduced, particularly for the Greenland shore sites implying significant regional effects. Potentially, extreme SPEs that are orders of magnitude stronger than those observed during the recent decades can be recorded in cosmogenic isotope data, and a proper model is needed to study them. Here we present a model of the production and transport of ¹⁰Be for a major solar energetic particle event (GLE 69) and analyze the geographical pattern of the beryllium concentration.

How to cite: Golubenko, K., Rozanov, E., Kovaltsov, G., Baroni, M., and Usoskin, I.: Modelling of atmospheric transport of SEP-induced cosmogenic 10Be using CCM SOCOL-AER2-BE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7171, https://doi.org/10.5194/egusphere-egu23-7171, 2023.

Posters virtual: Wed, 26 Apr, 14:00–15:45 | vHall ST/PS

Chairpersons: Ross Pallister, Nina Dresing

vSP.5

EGU23-13801

ST1.10

ECS

Witnessing a Forbush Decrease with a Microscintillator Ionisation Detector over the Atlantic Ocean

Justin Tabbett, Karen Aplin, and Susana Barbosa

A novel ionisation detector, previously deployed on meteorological radiosonde flights, has demonstrated responsivity to X-rays and gamma radiation, and additionally, is thought to be sensitive to ionising radiation from cosmic rays. The PiN detector, composed of a 1x1x0.8 cm³CsI(Tl) microscintillator coupled to a PiN photodiode, was deployed on the NRP Sagres sailing vessel on a cruise in the Atlantic between Portugal and the Azores in 2021. The instrument can determine both the count rate and energy of incoming ionising radiation particles.

The instrument was operational during the voyage in November 2021 when a coronal mass ejection event induced a sudden decrease in the observed cosmic ray intensity, known as a Forbush decrease. We present data recorded by the ionisation detector during this period, to characterise the instrument’s ability to detect cosmic ray events, and we compare the performance with neutron monitoring stations Oulu in Finland, and Dourbes in Belgium. As the PiN detector provides spectral and count rate data, it is possible to group events by their energy, and investigate the count rates of specific energy regimes. This approach is useful as many sources – including high and low energy ionising radiation from cosmic rays – contribute to the background energy spectrum. As a result, more meaningful comparisons and relationships can be established with the neutron monitoring stations.

How to cite: Tabbett, J., Aplin, K., and Barbosa, S.: Witnessing a Forbush Decrease with a Microscintillator Ionisation Detector over the Atlantic Ocean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13801, https://doi.org/10.5194/egusphere-egu23-13801, 2023.

Discussion

vSP.6

EGU23-1741

ST1.10

ECS

Energy Spectrum of Solar Energetic Electron Events Over 25 Years

Wen Wang, Linghua Wang, Zixuan Liu, Samuel Krucker, and Robert F. Wimmer-Schweingruber

Solar Energetic electron (SEE) events are the most common solar particle acceleration phenomenon detected in situ in the interplanetary medium and the energy spectrum of SEE events carries crucial information on the acceleration and/or transport processes of SEEs. In our research, we investigate the peak flux energy spectrum of 458 SEE events with a clear velocity dispersion detected at energies from ≤ 4.2 keV to ≥ 108 keV by Wind/3DP from 1994 December through 2019 December, utilizing a pan-spectrum fitting method. According to the fitted spectral parameters, these 458 events are self-consistently classified into five spectral shapes: 304 DDPL events, 32 UDPL events, 23 SPL events, 44 ER events and 55 LP events. The DDPL events can be further divided in to two types: 231 E_B≥20 keV DDPL events and 73 E_B<20 keV DDPL events, since the distribution of break energy E_B exhibits a primary peak around 60 keV and a secondary peak around 7 keV, separated by a dip at ~20 keV. The E_B≥20 keV (E_B<20 keV) DDPL events exhibit a power-law spectral index of 2.0^+0.2_-0.2(2.1^+0.3_-0.3) (values shown in a form of A^+B_-C means the median value with the first and the third quartiles) at energies below E_B=5.6^+2.3_-2.4 keV (60⁺²³_-12 keV) and index of 3.3^+0.5_-0.3 (3.9^+0.6_-0.7) at energies above.The UDPL events have a spectral index of 3.0^+0.3_-0.3 at energies below E_B=5.1^+4.2_-1.8 keV and index of 2.2^+0.2_-0.3 at energies above. The SPL events shows a spectral index of 2.8^+0.5_-0.2. The ER events exhibit a spectral index 1.9^+0.3_-0.3 at energies below E_c=30⁺¹⁹_-10 keV. The six spectrum types also behave differently in the relationship between spectral parameters and in solar cycle variations. Furthermore, propagation effects in the IPM from the Sun to 1 AU appear to have no obvious influence on the spectral shape of most SEE events. These results suggest that the formation of SEE events can involve complex processes/sources.

How to cite: Wang, W., Wang, L., Liu, Z., Krucker, S., and Wimmer-Schweingruber, R. F.: Energy Spectrum of Solar Energetic Electron Events Over 25 Years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1741, https://doi.org/10.5194/egusphere-egu23-1741, 2023.

vSP.7

EGU23-11362

ST1.10

ECS

Solar Energetic Electron Events with a Spectral Bump

Wenyan Li, Linghua Wang, and Wen Wang

The energy spectrum of solar energetic electron (SEE) events carries crucial information on the origin/acceleration of energetic electrons at the Sun. Using the Wind 3DP electron measurements at ~1 to 200 keV during 1995-2019, we select 11 good SEE events with a bump-like break in the peak flux vs. energy spectrum, different from the typical SEE events with a double-power-law spectrum. For the selected 11 events, the background-subtracted electron peak flux versus energy spectrum fits well to two functions: the sum of a single-power-law and a Gaussian function (spectral function #1) and the product of a single-power-law and the natural exponential form of a Gaussian function (spectral function #2). For the spectral function #1 (#2), on average, the fitted spectral index is 2.6±0.4 (2.7±0.6), significantly larger than the low-energy power-law index of typical SEE events, while the fitted center energy of spectral bump is 24±7 keV (75±38 keV) and the ratio of bump width and center is 2.0±0.7 (3.4±2.8). Among these 11 events, respectively, ~78%, ~89%, ~90%, 100% and ~55% are associated with GOES SXR flares, RHESSI HXR flares, west-limb CMEs, type III radio bursts and type II radio bursts. Thus, these bump events have a stronger association with flares, coronal mass ejections (CMEs) and type II radio bursts, compared to the typical SEE events. In addition, we find a positive correlation between the center energy of bump and the CME speed. Therefore, we come up with an acceleration picture of these bump SEE events: the power-law portion is probably accelerated by flares with the acceleration efficiency larger at lower energies, while the bump portion is likely accelerated in CME-related processes with the acceleration efficiency increasing with the CME speed.

How to cite: Li, W., Wang, L., and Wang, W.: Solar Energetic Electron Events with a Spectral Bump, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11362, https://doi.org/10.5194/egusphere-egu23-11362, 2023.