ST1.5

Pioneering exploration of the solar corona and near-Sun environment – Latest results from Parker Solar Probe

The Sun’s corona is the birthplace of the solar wind, coronal mass ejections, associated shock waves, and solar energetic particles which all are fundamental drivers of space weather. The key physical processes at the origin of these phenomena, i.e., the heating and acceleration of the coronal plasma and energetic particles, are not completely understood to date. During EGU 2022, Parker Solar Probe (PSP) would have completed 11 of its 24 scheduled orbits around the Sun. During orbits 10 and 11, the spacecraft will go as close as 13.3 solar radii from the Sun’s center. PSP has already provided a treasure trove worth of in-situ and remote sensing data that have revealed phenomena never seen before in terms of generation of solar wind turbulence, fine-structures of coronal mass ejections, solar energetic particle flows, traces of dust particles and even in planetary physics on Venus. The formal commissioning phase of Solar Orbiter (SolO) ended in mid-June 2020 and valuable data has been provided during the cruise phase of the mission, primarily by the in-situ instruments. The nominal phase of the mission will start at the end of 2021. Combining the PSP and SolO observations with observations from other space-born missions and ground-based observatories (e.g., SDO, STEREO, Proba2, ACE, WIND, DSCOVR, and DKIST ), and with theoretical models is a challenging and exciting task. This session invites scientific contributions on all aspects of research addressed to the exploration of our near-Sun environment, with special focus on the new observations from PSP and SolO and other complementary observations and models.

Convener: Volker Bothmer | Co-conveners: Olga Malandraki, Nour Raouafi, Alexis Rouillard, Manuela Temmer
Presentations
| Thu, 26 May, 17:00–18:20 (CEST)
 
Room 1.14

Presentations: Thu, 26 May | Room 1.14

Chairpersons: Volker Bothmer, Olga Malandraki, Manuela Temmer
17:00–17:05
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EGU22-565
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ECS
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On-site presentation
Thomas Woolley, Lorenzo Matteini, Timothy S. Horbury, Stuart D. Bale, Ronan Laker, Lloyd D. Woodham, and Julia E. Stawarz

To date, Parker Solar Probe has completed ten solar encounters and measured a wealth of in-situ data down to heliocentric distances of ~13 solar radii. This data provides a novel opportunity to investigate the near-Sun environment and understand the young slow solar wind. Typically, the slow solar wind observed in the inner heliosphere is split into an Alfvenic and a non-Alfvenic component. The Alfvenic slow wind is thought to originate from overexpanded coronal hole field lines, whereas the non-Alfvenic slow wind could originate from active regions, transient events, or reconnection at the tips of helmet streamers. In this work, we find structures associated with non-Alfvenic slow wind in the low latitude wind measured by Parker Solar Probe. We identify at least two distinct types of structure using magnetic field magnitude, electron pitch angle distributions, and electron number density. After statistically analysing these structures, with a focus on their plasma properties, shape, and location with respect to the heliospheric current sheet, we link them to solar origins. We find structures that are consistent with the plasma blobs seen previously in remote sensing observations.

How to cite: Woolley, T., Matteini, L., Horbury, T. S., Bale, S. D., Laker, R., Woodham, L. D., and Stawarz, J. E.: Linking In-situ Magnetic and Density Structures in the Low Latitude Slow Solar Wind to Solar Origins, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-565, https://doi.org/10.5194/egusphere-egu22-565, 2022.

17:05–17:10
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EGU22-1353
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On-site presentation
Mihir Desai and the the Parker Solar Probe ISOIS, FIELDS & SWEAP Teams

We report observations of <100 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with three separate crossings of the heliospheric current sheet that occurred near perhelia during PSP encounters 7, 8, and 9. In particular, we compare and contrast the ST ion time-intensity profiles, velocity dispersion, pitch-angle distributions, spectral forms, and maximum energies during the three HCS crossings. We find that these unique ST observations are remarkably different in each case, with those during E07 posing the most serious challenges for existing models of ST ion production in the inner heliosphere. In contrast, the ISOIS observations during E08 appear to be consistent with a scenario in which ST ions escape out of the reconnection exhausts into the separatrix layers after getting accelerated up to ~50-100 keV/nucleon by HCS-associated magnetic reconnection-driven processes. Finally, ST ions during the E09 HCS crossing have properties that are somewhat similar to those seen during both E07 and E08 crossings, with ion intensities being higher outside the exhausts and the separatrices, but significant intensity increases are also observed inside the reconnection exhausts. We discuss these new observations in terms of local versus remote acceleration sources as well as in terms of expectations of existing ST ion production and propagation, including reconnection-driven and diffusive acceleration in the inner heliosphere.

How to cite: Desai, M. and the the Parker Solar Probe ISOIS, FIELDS & SWEAP Teams: Suprathermal Ion Observations Associated with the Heliospheric Current Sheet Crossings during Parker Solar Probe Encounters 7, 8, and 9, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1353, https://doi.org/10.5194/egusphere-egu22-1353, 2022.

17:10–17:15
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EGU22-1357
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On-site presentation
Jana Safrankova, Zdenek Nemecek, Frantisek Nemec, Tereza Durovcova, Luca Franci, and Alexander Pitna

The solar wind is a unique laboratory to study the turbulent processes occurring in a collisionless plasma with high Reynolds numbers. The paper analyzes power spectra of magnetic field fluctuations that are computed in the frequency range around the break between inertial and kinetic scales. We use observations made during first nine Parker Solar Probe encounters and compare them with observations of the spacecraft moving in other distances from the Sun (e.g., Solar Orbiter) and closer to 1 AU (Wind). A preliminary analysis of magnetic field fluctuations based on PSP and Wind measurements from the MHD to kinetic scales has shown that a relative level of compressive fluctuations increases until 0.25 AU and remains constant till 1 AU whereas a relative level of perpendicular fluctuations does not change with the distance from the Sun. We can conclude that the B slope is controlled by different process(es) close to the Sun against 1 AU and that, in spite of expectations, the critical distance for turbulence evolution is as large as 0.25 AU. We also discuss the role of important physical parameters (e.g., ion beta, temperature anisotropy, collisional age, magnetic field fluctuation amplitude) determining the properties of the turbulent cascade in different heliospheric locations.

How to cite: Safrankova, J., Nemecek, Z., Nemec, F., Durovcova, T., Franci, L., and Pitna, A.: Evolution of power spectral density of magnetic field fluctuations in the inner heliosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1357, https://doi.org/10.5194/egusphere-egu22-1357, 2022.

17:15–17:20
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EGU22-1809
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On-site presentation
Anthony Rasca, William Farrell, Robert MacDowall, Stuart Bale, and Justin Kasper

The first solar encounters by the Parker Solar Probe revealed the magnetic field to be dominated by short field reversals in the radial direction referred to as "switchbacks."  While radial velocity and proton temperature were shown to increase inside the switchbacks, B exhibits very brief dropouts only at the switchback boundaries.  Brief intensifications in spectral density measurements near the electron plasma frequency, fpe, have also been observed at these boundaries, indicating the presence of plasma waves triggered by electron beams.  We perform a correlative study using observations from the Parker FIELDS Radio Frequency Spectrometer (RFS) and Fluxgate Magnetometer (MAG) to compare occurrences of spectral density intensifications at the electron plasma frequency (fpe intensifications) and B dropouts at switchback boundaries during Parker's first and second solar encounters.  We find that only a small fraction of minor B dropouts are associated with fpe intensifications.  This fraction increases with B dropout size until all dropouts are associated with fpe intensifications.  This suggests that in the presence of strong B dropouts, electron currents that create the perturbation in B along the boundaries are also stimulating plasma waves such as Langmuir waves.

How to cite: Rasca, A., Farrell, W., MacDowall, R., Bale, S., and Kasper, J.: Correlated Magnetic Field Dropouts and Plasma Wave Activity at Switchback Boundaries as Observed by Parker Solar Probe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1809, https://doi.org/10.5194/egusphere-egu22-1809, 2022.

17:20–17:25
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EGU22-2273
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On-site presentation
Manuela Temmer and Volker Bothmer

Helios 1 and 2 data, covering the distance range from 0.3-1au, have been analysed to derive the characteristics of various substructures of interplanetary coronal mass ejections (ICMEs). We have investigated a data sample of 40 events observed by the Helios 1/2 spacecraft during the time period 1974-1981 with respect to the characteristics of different ICME features, such as sheath regions, leading edges and the magnetic ejecta (ME) themselves. For comparison and to investigate events at distances even closer to the Sun, we add a sample of 5 ICMEs observed with Parker Solar Probe during 2018-2021. We study the sheath density variations over distance and relate those to the ambient solar wind speed. The results show that the sheath region is moderately anti-correlated with the solar wind speed ahead of the disturbance. We further find that the sheath density becomes dominant over the ME density beyond about 0.2au and that its spatial extent constantly increases with distance. The results are important for better understanding the CME mass evolution due to sheath enlargements. Based on these analyses we derive an empirical relation between the sheath density and the local solar wind plasma speed upstream of the ICME shock. The empirical results can be used to model the sheath structure and help improve our understanding about CME propagation in the inner heliosphere.

How to cite: Temmer, M. and Bothmer, V.: Sheath characteristics of interplanetary coronal mass ejections derived from Helios and PSP data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2273, https://doi.org/10.5194/egusphere-egu22-2273, 2022.

17:25–17:30
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EGU22-2638
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ECS
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Virtual presentation
Panisara Thepthong, Peera Pongkitiwanichakul, and David Ruffolo

Alfvénicity is a well-known property of the solar wind. The magnetic and velocity fluctuations are highly correlated over much of the region between the Sun and the Earth. The Parker Solar Probe (PSP) spacecraft enables us to probe Alfvénicity closer to the Sun than before. One previous finding is that the Alfvén ratio increases as the scales become smaller, as shown in some works by using Fourier analysis. This work measures Alfvénicity from PSP observations using 2nd-order structure functions and other quantities derived from magnetic and velocity increments as functions of time lag. We introduce a method to subtract noise from the velocity structure function. We also provide the relation between a time lag in our work and the frequency that contributes most to the 2nd-order structure function for such a time lag. This relation allows a direct comparison between functions of time lag and Fourier spectra. This research has been supported in part by grant RGNS 63-045 from Office of the Permanent Secretary, Ministry of Higher Education, Science, Research and Innovation, and by grant RTA6280002 from Thailand Science Research and Innovation.

How to cite: Thepthong, P., Pongkitiwanichakul, P., and Ruffolo, D.: Alfvénicity of velocity and magnetic field Increments Observed by Parker Solar Probe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2638, https://doi.org/10.5194/egusphere-egu22-2638, 2022.

17:30–17:35
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EGU22-2945
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ECS
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On-site presentation
Xueyi Wang, Sandra Chapman, Richard Dendy, and Bogdan Hnat

The high Reynolds number solar wind flow provides a natural laboratory for the study of turbulence in-situ. Parker Solar Probe has to date executed nine sampling distances between 0.2 AU to 1 AU, providing an opportunity to study how turbulence evolves in the expanding solar wind. We focus on data from the PSP/FIELDS[1] and the PSP/SWEAP[2] experiments which provide magnetic field and plasma observations respectively at sub-second cadence. We have identified multiple intervals of uniform solar wind turbulence, selected to exclude coherent structures such as pressure pulses and current sheets, and in which the primary proton population velocity varies by less than 20% of its mean value. We focus on events of multiple-hour duration, which span the spectral scales from the approximately 1/f range at low frequencies, through the magnetohydrodynamic (MHD) inertial range of turbulence and into the kinetic range, below the ion gyrofrequency. We perform a Haar wavelet decomposition[3] which provides accurate estimations of the exponents of these power-law ranges of the spectra, and of higher-order moments. This allows us to study how the spectral exponents may vary with distance from the sun and with solar wind conditions such as the plasma beta. We perform this analysis for both the magnetic field components and magnitude, which track Alfvenic and compressive turbulent fluctuations, respectively. At 1 AU, compressive fluctuations are known to exhibit scaling properties distinct from that of the individual magnetic field components.[4] Here we will investigate this behaviour at different distances from the Sun, plasma beta, and proton density.

We acknowledge the NASA Parker Solar Probe Mission and the SWEAP team led by J. Kasper and the FIELDS team led by S. D. Bale for use of data.

[1] Bale, S.D., Goetz, K., Harvey, P.R. et al. The FIELDS Instrument Suite for Solar Probe Plus.Space Sci Rev 204, 49–82 (2016). https://doi.org/10.1007/s11214-016-0244-5

[2] Kasper, J.C., Abiad, R., Austin, G. et al. Solar Wind Electrons Alphas and Protons (SWEAP) Investigation: Design of the Solar Wind and Coronal Plasma Instrument Suite for Solar Probe Plus. Space Sci Rev 204, 131–186 (2016). https://doi.org/10.1007/s11214-015-0206-3

[3] Kiyani, K.H., Chapman, S.C., Sahraoui, F., Hnat, B., Fauvarque, O., Khotyaintsev, Y.V.: Enhanced Magnetic Compressibility and Isotropic Scale Invariance at Sub-ion Larmor Scales in Solar Wind Turbulence. The Astrophysical Journal 763(1), 10 (2012). https://doi.org/10.1088/0004-637x/763/1/10

[4] Hnat, B., Chapman, S., Gogoberidze, G., Wicks, R.: Scale-free texture of the fast solar wind. Physical review. E, Statistical, nonlinear, and soft matter physics 84, 065401 (2011). https://doi.org/10.1103/PhysRevE.84.065401
 
 
 
 
 
 

How to cite: Wang, X., Chapman, S., Dendy, R., and Hnat, B.: Wavelet analysis of scaling in plasma fluctuations in the magnetohydrodynamic range of solar wind turbulence seen by Parker Solar Probe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2945, https://doi.org/10.5194/egusphere-egu22-2945, 2022.

17:35–17:40
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EGU22-3195
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ECS
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On-site presentation
Sabrina F. Tigik, Andris Vaivads, and David M. Malaspina

Near-fce harmonic waves are prevalent in the high-frequency electric field spectrum during Parker Solar Probe's (PSP) close encounters with the Sun. These waves are electrostatic and tend to occur in regions of a relatively stable magnetic field with low broadband magnetic fluctuation levels. We show that the emissions of near-fce harmonic waves are strongly connected to the magnetic field direction. We express the magnetic field direction in terms of spherical angles, where θB is the elevation angle and φB is the azimuthal angle. Then, we show that near-fce harmonics emissions occur when the magnetic field points in a narrow angular range, bounded by 80° ≤ θB ≤ 100° and 10° ≤ φB ≤ 30°, in most of the cases. We also show that the influence of magnetic field direction on near-fce harmonic waves goes down to the shortest time scales the FIELDS instrument can access. These results suggest that cross-scale interaction might play an essential role in the dynamics of the near-fce harmonics measured by PSP at small radial distances from the Sun. It may also provide important clues about the origin of these waves and their role at the early stages of solar wind evolution.

How to cite: F. Tigik, S., Vaivads, A., and M. Malaspina, D.: The emission of near-fce harmonic waves at small radial distances from the Sun, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3195, https://doi.org/10.5194/egusphere-egu22-3195, 2022.

17:40–17:45
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EGU22-3859
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On-site presentation
Jan Soucek, Sampath Bandara, David Pisa, Ondrej Santolik, Milan Maksimovic, Thomas Chust, Yuri Khotyaintsev, Antonio Vecchio, Matthieu Kretzschmar, Robert Wimmer-Schweingruber, Lars Berger, Javier Rodriquez-Pacheco, and Raul Gomez-Herrero

We investigate the polarization of Langmuir waves observed by the Time Domain Sampler (TDS) module of the Radio and Plasma Waves instrument on Solar Orbiter during several extensive Type III burst events. During its two-year-long cruise phase, Solar orbiter often crossed the source region of the Type III radio emission and observed the Langmuir waves generated by solar energetic electrons. The waves are known to exhibit complex modulation and often non-trivial elliptical polarization which sometimes rapidly changes on the timescales of tens of milliseconds. We show that the observed waveforms are typically composed of multiple sub-packets with a relatively short coherence length. We investigate the correlation between the polarization of the waves, simultaneously observed energetic electrons beams and other plasma properties.

How to cite: Soucek, J., Bandara, S., Pisa, D., Santolik, O., Maksimovic, M., Chust, T., Khotyaintsev, Y., Vecchio, A., Kretzschmar, M., Wimmer-Schweingruber, R., Berger, L., Rodriquez-Pacheco, J., and Gomez-Herrero, R.: Polarization of Langmuir waves observed by RPW-TDS instrument on Solar Orbiter during Type III radio bursts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3859, https://doi.org/10.5194/egusphere-egu22-3859, 2022.

17:45–17:50
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EGU22-3917
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ECS
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On-site presentation
Ronan Laker, Tim Horbury, Lorenzo Matteini, Thomas Woolley, Julia Stawarz, and Stuart Bale

Following their presence during Parker Solar Probe’s (PSP) first encounter, switchbacks have become an active area of research with several proposed mechanisms for their formation. Many of these theories have testable predictions, although it is not trivial to compare simulation results with in-situ data from PSP. For example, there is some debate regarding the deflection direction of switchbacks, with some theories predicting a consistent magnetic deflection in the +T direction in the RTN coordinate system. Such arguments are largely focussed on the first two PSP encounters, as these are the most studied encounters in the literature. We examine the deflection direction of switchbacks for the first eight PSP encounters, with the aim to clear up any ambiguity regarding this property of switchbacks. Much like the earlier results of Horbury et al. 2020 (during the first encounter) we find that switchbacks tend to deflect in the same direction for hours at a time. Although there is some consistency in deflection direction within an individual encounter, crucially we find that there is no preferred deflection direction across all the encounters. We speculate about the cause of these results and what implications they may have for switchback formation theories.

How to cite: Laker, R., Horbury, T., Matteini, L., Woolley, T., Stawarz, J., and Bale, S.: On the Deflections of Switchbacks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3917, https://doi.org/10.5194/egusphere-egu22-3917, 2022.

17:50–17:55
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EGU22-4130
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On-site presentation
David Pisa, Jan Soucek, Ondrej Santolik, Miroslav Hanzelka, Milan Maksimovic, Antonio Vecchio, Yuri Khotyaintsev, Thomas Chust, Matthieu Kretzschmar, Lorenzo Matteini, and Timothy Horbury

On November 27, 2021, Solar Orbiter completed its only flyby of Earth on its way to the following Sun’s encounter in March 2022. Although this fast flyby was performed primarily to decrease the spacecraft’s velocity and change orbit to get closer to the Sun, the Radio and Plasma Wave (RPW) instrument had the opportunity to perform high cadence measurements in the Earth’s magnetosphere. We review the main observation of the Time Domain Sampler (TDS) receiver, a part of the RPW instrument, made during this flyby at frequencies below 200 kHz. The TDS receiver operated in a high cadence mode providing us with the regular waveform snapshot with 62 ms length every ten seconds for two electric components. Besides the regular captures, we have got more than five hundred onboard classified snapshots and the statistical products with a sixteen-second cadence. Before entering the terrestrial magnetosphere around 02:30UT, the spacecraft wandered through the foreshock region, registering intense bursts of Langmuir waves. After the bowshock crossing, Solar Orbiter was for more than two hours in the morning sector of the magnetosphere, recording various plasma wave modes. The closest approach was reached at 04:30UT above North Africa at an altitude of 460 km. Then the spacecraft continued into the Earth’s tail and entered the magnetosheath around 13:00UT. After 15:00UT, the Solar Orbiter crossed the bowshock, and bursts of Langmuir waves were detected again pointing out to the deep downstream foreshock region. Further from the Earth, intense Auroral Kilometric Radiation (AKR) at frequencies above 100 kHz was also detected.

How to cite: Pisa, D., Soucek, J., Santolik, O., Hanzelka, M., Maksimovic, M., Vecchio, A., Khotyaintsev, Y., Chust, T., Kretzschmar, M., Matteini, L., and Horbury, T.: Observations of the Time Domain Sampler receiver from the Radio and Plasma Wave instrument during the Solar Orbiter Earth flyby , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4130, https://doi.org/10.5194/egusphere-egu22-4130, 2022.

17:55–18:05
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EGU22-8923
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solicited
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Virtual presentation
Jasmina Magdalenic, Senthamizh Pavai Valliappan, and Luciano Rodriguez

The recently available novel Parker Solar Probe (PSP) observations allow mapping of the solar wind characteristics in the low solar corona, at only a few tens of solar radii, and study the characteristics of the solar wind and its transients close to the Sun. The first few perihelion passes of the PSP revealed the highly variable structure of the solar wind. These observations provided the unique possibility to study the solar wind originating from small coronal holes. Such studies were previously not possible as the majority of the in situ observations were taken at distances of about 1 AU, and the association of the solar wind originating from the small coronal holes and its sources on the Sun was extremely unreliable. We employ a magnetic connectivity tool (developed by ESA’s MADAWG group) to associate the solar wind parcels observed by the PSP with their source regions on the Sun.  Our study encompasses the first eight PSP perihelion passes, using a time window of about three weeks around each perihelion. The first results indicate that we can well distinguish and identify the solar wind observed by the PSP originating not only from the big, but also from the small coronal holes.

How to cite: Magdalenic, J., Valliappan, S. P., and Rodriguez, L.: Origin of the solar wind observed by PSP , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8923, https://doi.org/10.5194/egusphere-egu22-8923, 2022.

18:05–18:10
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EGU22-8932
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ECS
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Virtual presentation
Senthamizh Pavai Valliappan, Jasmina Magdalenic, Luciano Rodriguez, Stefaan Poedts, and Evangelia Samara

During recent decades, numerous studies were devoted to improve our understanding of the origin and the propagation of the fast solar wind, and its accurate modelling. The solar wind characteristics were poorly mapped up to now by the in situ observations, available mostly only at about 1AU. The novel Parker Solar Probe (PSP) observations, that are employed in this study, allow us to map the solar wind characteristics in the low solar corona at only few tens of solar radii, and to study the solar wind characteristics. These observations are also very important for understanding how accurately we can model the solar wind characteristics employing models such as EUHFORIA (European heliospheric forecasting information asset, Pomoell & Poedts, 2018), at distances rather close to the Sun.
In this study, we inspect the solar wind characteristics during the first eight closest PSP approaches to the Sun. The solar wind plasma characteristics observed by PSP are compared with the modelling results using the default set-up of EUHFORIA. We also calibrate the inner boundary (0.1 AU) conditions in EUHFORIA, but without changing the Wang-Sheeley-Arge formula which describes the solar wind characteristics at the inner boundary. The aim is to better model the solar wind at distances close to the Sun. We also use a magnetic connectivity tool (developed by ESA’s MADAWG group) to better associate the fast solar wind with its source region on the Sun.

How to cite: Valliappan, S. P., Magdalenic, J., Rodriguez, L., Poedts, S., and Samara, E.: Solar wind modelling with EUHFORIA and comparison with the PSP observations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8932, https://doi.org/10.5194/egusphere-egu22-8932, 2022.

18:10–18:15
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EGU22-9673
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Virtual presentation
Chuanpeng Hou, Jiansen He, Die Duan, Huichao Li, and Yajie Chen

During its perihelion encounter, Parker Solar Probe (PSP) has observed abundant kink and switchback patterns of magnetic field lines in the young solar wind. Such switchback structures have gained widespread attention due to their manifestation of Alfvenic and compressional properties, such as velocity enhancement, plasma density, and temperature variation. In particular, the origin mechanism has been a hot topic and waits to be observationally confirmed. Here we use a two-step ballistic backmapping method (tracing along the Parker Spiral and the PFSS-solution extrapolated from the GONG synoptic magnetogram) to determine the foot-points of the magnetic lines during switchback events measured by PSP on 24th-27th Jan. 2020. We identify ten jets corresponding to the PSP-switchbacks and find relevance between jets and switchback patches. We find that jets excite at the height of around low corona and position of chromospheric network boundaries. About 70% of jets accompany a magnetic cancelation, while 30% of jets are related to magnetic emergence. The variation in magnetic flux corresponding to magnetic cancelation and magnetic emergence is quantitatively equal to that of radial magnetic flux associated with switchback patches. These features suggest that switchbacks may originate from an interchange magnetic reconnection at chromospheric network boundaries, which provides direct evidence of switchbacks' solar origin. 

How to cite: Hou, C., He, J., Duan, D., Li, H., and Chen, Y.: From Magnetic Reconnection at Chromospheric Network Boundaries to Switchbacks in the Inner Heliosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9673, https://doi.org/10.5194/egusphere-egu22-9673, 2022.

18:15–18:20
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EGU22-12654
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On-site presentation
Raffaella DAmicis, Roberto Bruno, Rossana De Marco, Marco Velli, Daniele Telloni, Denise Perrone, Luca Sorriso-Valvo, and Olga Panasenco

The solar wind is a highly variable, weakly collisional plasma originating from the Sun. The recent launches of PSP and Solar Orbiter have opened the way for the exploration of the innermost regions of our solar system and will greatly advance our understanding of several plasma phenomena occurring in the near-Sun environment, such as the heating and the acceleration of the solar wind. 

Plasma waves and wave-particle interactions play a relevant role in such phenomena, determining significant deviations of the Velocity Distribution Function (VDF) from the Local Thermodynamic Equilibrium. These deviations retain information of the interaction of particles with the turbulent electromagnetic fields and can be identified as thermal anisotropy, or non-thermal ion beams and heavy ion differential streaming in the ion component of the solar wind. This study will cover these topics with particular reference to new in-situ data from Solar Orbiter, PSP and with observations at L1  (e.g. Wind), with a focus on the central role Alfvénic fluctuations play in the evolution of the VDF features mentioned above.

How to cite: DAmicis, R., Bruno, R., De Marco, R., Velli, M., Telloni, D., Perrone, D., Sorriso-Valvo, L., and Panasenco, O.: Non-thermal features in proton and alpha velocity distribution functions in the solar wind in the inner heliosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12654, https://doi.org/10.5194/egusphere-egu22-12654, 2022.