Deriving CME volume and density from remote sensing data

2021 ◽  
Author(s):  
Manuela Temmer ◽  
Lukas Holzknecht ◽  
Mateja Dumbovic ◽  
Bojan Vrsnak ◽  
Nishtha Sachdeva ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Remote Sensing Data ◽  
Propagation Speed ◽  
Solar Wind Density ◽  
Sheath Region ◽  
Pile Up ◽  
Mass Ejection ◽  
Interplanetary Propagation

<p>Using combined STEREO-SOHO white-light data, we present a method to determine the volume and density of a coronal mass ejection (CME) by applying the graduated cylindrical shell model (GCS) and deprojected mass derivation. Under the assumption that the CME  mass is roughly equally distributed within a specific volume, we expand the CME self-similarly and calculate the CME density for distances close to the Sun (15–30 Rs) and at 1 AU. The procedure is applied on a sample of 29 well-observed CMEs and compared to their interplanetary counterparts (ICMEs). Specific trends are derived comparing calculated and in-situ measured proton densities at 1 AU, though large uncertainties are revealed due to the unknown mass and geometry evolution: i) a moderate correlation for the magnetic structure having a mass that stays rather constant and ii) a weak correlation for the sheath density by assuming the sheath region is an extra mass - as expected for a mass pile-up process - that is in its amount comparable to the initial CME deprojected mass. High correlations are derived between in-situ measured sheath density and the solar wind density and solar wind speed as measured 24 hours ahead of the arrival of the disturbance. This gives additional confirmation that the sheath-plasma indeed stems from piled-up solar wind material. While the CME interplanetary propagation speed is not related to the sheath density, the size of the CME may play some role in how much material is piled up.</p>

Relating CME density derived from remote sensing data to CME sheath solar wind plasma pile up as measured in-situ

2020 ◽  
Author(s):  
Manuela Temmer ◽  
Lukas Holzknecht ◽  
Mateja Dumbovic ◽  
Bojan Vrsnak ◽  
Nishtha Sachdeva ◽  
...  
Keyword(s):  
Solar Wind ◽  
Magnetic Structure ◽  
Interplanetary Space ◽  
Remote Sensing Data ◽  
Solar Wind Plasma ◽  
Proton Density ◽  
Observational Assessment ◽  
Sheath Region ◽  
Pile Up

<p>For better estimating the drag force acting on coronal mass ejections (CMEs) in interplanetary space and ram-pressure at planets, improved knowledge of the evolution of CME density/mass is highly valuable. We investigate a sample of 29 well observed CME-ICME events, for which we determine the de-projected 3D mass (STEREO-A and -B data), and the CME volume using GCS modeling (STEREO, SoHO). Expanding the volume to 1AU distance, we derive the density and compare the results to in-situ proton density measurements separately for the ICME sheath and magnetic structure. A fair agreement between calculated and measured density is derived for the magnetic structure as well for the sheath if taking into account mass pile up of solar wind plasma. We give evidence and observational assessment that during the interplanetary propagation of a CME 1) the magnetic structure has rather constant mass and 2) the sheath region at the front of the driver is formed from piled-up mass that is rather depending on the solar wind density ahead of the CME, than on the CME speed. </p>

MHD simulations of magnetospheric response to a strong solar wind density pulse

2021 ◽  
Author(s):  
Andrey Samsonov ◽  
Jennifer A. Carter ◽  
Graziella Branduardi-Raymont ◽  
Steven Sembay
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Solar Wind Density ◽  
Ionospheric Currents ◽  
X Ray ◽  
Interplanetary Coronal Mass Ejection ◽  
Explorer Mission ◽  
The One ◽  
Mass Ejection ◽  
Present Simulation

<p>On 16-17 June 2012, an interplanetary coronal mass ejection with an extremely high solar wind density (~100 cm<sup>-3</sup>) and mostly strong northward (or eastward) interplanetary magnetic field (IMF) interacted with the Earth’s magnetosphere. We have simulated this event using global MHD models. We study the magnetospheric response to two solar wind discontinuities. The first is characterized by a fast drop of the solar wind dynamic pressure resulting in rapid magnetospheric expansion. The second is a northward IMF turning which causes reconfiguration of the magnetospheric-ionospheric currents. We discuss variations of the magnetopause position and locations of the magnetopause reconnection in response to the solar wind variations. In the second part of our presentation, we present simulation results for the forthcoming SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) mission. SMILE is scheduled for launch in 2024. We produce two-dimensional images that derive from the MHD results of the expected X-ray emission as observed by the SMILE Soft X-ray Imager (SXI). We discuss how SMILE observations may help to study events like the one presented in this work.</p>

scholarly journals On acceleration of <1 MeV/n He ions in the corotating compression regions near 1 AU: STEREO observations

2009 ◽  
Vol 27 (9) ◽  
pp. 3677-3690 ◽  
Author(s):  
R. Bučík ◽  
U. Mall ◽  
A. Korth ◽  
G. M. Mason
Keyword(s):  
Solar Wind ◽  
Total Pressure ◽  
Solar Wind Speed ◽  
Shock Acceleration ◽  
Model Parameters ◽  
Corotating Interaction Region ◽  
Reverse Shock ◽  
Compression Region ◽  
Model Predictions

Abstract. Observations of multi-MeV corotating interaction region (CIR) ions are in general consistent with models of CIR shock acceleration and transport. The presence of suprathermal particles near 1 AU in unshocked compression regions is not adequately explained. Nonetheless, more recent works demonstrate that unshocked compression regions associated with CIRs near 1 AU could energize particles. In the energy range from ~0.1 to ~1 MeV/n we investigate CIR events observed in 2007–2008 by the STEREO A and B spacecraft. We treat the predictions of compression acceleration by comparing the observed ion intensities with the model parameters. These observations show that the ion intensity in CIR events with in-situ reverse shock is well organized by the parameters which characterize the compression region itself, like compression width, solar wind speed gradients and the total pressure. In turn, for CIR events with the absence of the shocks the model predictions are not fulfilled.

scholarly journals SMEI 3D RECONSTRUCTION OF A CORONAL MASS EJECTION INTERACTING WITH A COROTATING SOLAR WIND DENSITY ENHANCEMENT: THE 2008 APRIL 26 CME

2010 ◽  
Vol 724 (2) ◽  
pp. 829-834 ◽  
Author(s):  
B. V. Jackson ◽  
A. Buffington ◽  
P. P. Hick ◽  
J. M. Clover ◽  
M. M. Bisi ◽  
...  
Keyword(s):  
Solar Wind ◽  
3D Reconstruction ◽  
Coronal Mass Ejection ◽  
Solar Wind Density ◽  
Density Enhancement ◽  
Mass Ejection

scholarly journals Ground-based magnetometer determination of in situ Pc4-5 ULF electric field wave spectra as a function of solar wind speed

2012 ◽  
Vol 117 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
I. Jonathan Rae ◽  
Ian R. Mann ◽  
Kyle R. Murphy ◽  
Louis G. Ozeke ◽  
David K. Milling ◽  
...  
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Electric Field ◽  
Solar Wind Speed ◽  
Wave Spectra ◽  
Field Wave

Large-scale electron solar wind parameters of the inner heliosphere with Parker Solar Probe/FIELDS

2020 ◽  
Author(s):  
Karine Issautier ◽  
Mingzhe Liu ◽  
Michel Moncuquet ◽  
Nicole Meyer-Vernet ◽  
Milan Maksimovic ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Statistical Study ◽  
Solar Wind Speed ◽  
The Sun ◽  
Solar Wind Parameters ◽  
Power Law Index ◽  
Probe Mission ◽  
Inner Heliosphere

&lt;p&gt;We present in situ properties of electron density and temperature in the inner heliosphere obtained during the three first solar encounters at 35 solar radii of the Parker Solar Probe mission. These preliminary results, recently shown by Moncuquet et al., ApJS, 2020, are obtained from the analysis of the plasma quasi-thermal noise (QTN) spectrum measured by the radio RFS/FIELDS instrument along the trajectories extending between 0.5 and 0.17 UA from the Sun, revealing different states of the emerging solar wind, five months apart. The temperature of the weakly collisional core population varies radially with a power law index of about -0.8, much slower than adiabatic, whereas the temperature of the supra-thermal population exhibits a much flatter radial variation, as expected from its nearly collisionless state. These measured temperatures are close to extrapolations towards the Sun of Helios measurements.&lt;/p&gt;&lt;p&gt;We also present a statistical study from these in situ electron solar wind parameters, deduced by QTN spectroscopy, and compare the data to other onboard measurements. In addition, we focus on the large-scale solar wind properties. In particular, from the invariance of the energy flux, a direct relation between the solar wind speed and its density can be deduced, as we have already obtained based on Wind continuous in situ measurements (Le Chat et al., Solar Phys., 2012). We study this anti-correlation during the three first solar encounters of PSP.&lt;/p&gt;

Understanding Solar Wind Formation by Identifying the Origins of In Situ Observations 

2021 ◽  
Author(s):  
Samantha Wallace ◽  
Nicholeen M. Viall ◽  
Charles N. Arge
Keyword(s):  
Solar Wind ◽  
Solar Wind Speed ◽  
Source Region ◽  
Heliospheric Current Sheet ◽  
Slow Solar Wind ◽  
The Sun ◽  
Flux Transport ◽  
Model Driven ◽  
In Situ Observations

&lt;p&gt;Solar wind formation can be separated into three physical steps &amp;#8211; source, release, and acceleration &amp;#8211; that each leave distinct observational signatures on plasma parcels.&amp;#160; The Wang-Sheeley-Arge (WSA) model driven by Air Force Data Assimilative Photospheric Flux Transport (ADAPT) time-dependent photospheric field maps now has the ability to connect in situ observations more rigorously to their precise source at the Sun, allowing us to investigate the physical processes involved in solar wind formation. &amp;#160;&amp;#160;In this talk, I will highlight my PhD dissertation research in which we use the ADAPT-WSA model to either characterize the solar wind emerging from specific sources, or investigate the formation process of various solar wind populations. &amp;#160;In the first study, we test the well-known inverse relationship between expansion factor (f&lt;sub&gt;s&lt;/sub&gt;) and observed solar wind speed (v&lt;sub&gt;obs&lt;/sub&gt;) for solar wind that emerges from a large sampling of pseudostreamers, to investigate if field line expansion plays a physical role in accelerating the solar wind from this source region.&amp;#160; We find that there is no correlation between f&lt;sub&gt;s&lt;/sub&gt; and v&lt;sub&gt;obs&lt;/sub&gt; at pseudostreamer cusps. In the second study, we determine the source locations of the first identified quasiperiodic density structures (PDSs) inside 0.6 au. Our modeling provides confirmation of these events forming via magnetic reconnection both near to and far from the heliospheric current sheet (HCS) &amp;#8211; a direct test of the Separatrix-web (S-web) theory of slow solar wind formation.&amp;#160; In the final study, we use our methodology to identify the source regions of the first observations from the Parker Solar Probe (PSP) mission.&amp;#160; Our modeling enabled us to characterize the closest to the Sun observed coronal mass ejection (CME) to date as a streamer blowout.&amp;#160; We close with future ways that ADAPT-WSA can be used to test outstanding questions of solar wind formation.&lt;/p&gt;

scholarly journals What geometrical factors determine the in situ solar wind speed?

2012 ◽  
Vol 57 (12) ◽  
pp. 1409-1414 ◽  
Author(s):  
Bo Li ◽  
Yao Chen ◽  
LiDong Xia
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Solar Wind Speed ◽  
Geometrical Factors

scholarly journals Quantifying the latitudinal representivity of in situ solar wind observations

2020 ◽  
Vol 10 ◽  
pp. 8 ◽  
Author(s):  
Mathew J. Owens ◽  
Matthew Lang ◽  
Pete Riley ◽  
Mike Lockwood ◽  
Amos S. Lawless
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Wind Speed ◽  
Solar Minimum ◽  
Numerical Models ◽  
Solar Wind Speed ◽  
Cycle Phase ◽  
Model State ◽  
Fast Wind

Advanced space-weather forecasting relies on the ability to accurately predict near-Earth solar wind conditions. For this purpose, physics-based, global numerical models of the solar wind are initialized with photospheric magnetic field and coronagraph observations, but no further observation constraints are imposed between the upper corona and Earth orbit. Data assimilation (DA) of the available in situ solar wind observations into the models could potentially provide additional constraints, improving solar wind reconstructions, and forecasts. However, in order to effectively combine the model and observations, it is necessary to quantify the error introduced by assuming point measurements are representative of the model state. In particular, the range of heliographic latitudes over which in situ solar wind speed measurements are representative is of primary importance, but particularly difficult to assess from observations alone. In this study we use 40+ years of observation-driven solar wind model results to assess two related properties: the latitudinal representivity error introduced by assuming the solar wind speed measured at a given latitude is the same as that at the heliographic equator, and the range of latitudes over which a solar wind measurement should influence the model state, referred to as the observational localisation. These values are quantified for future use in solar wind DA schemes as a function of solar cycle phase, measurement latitude, and error tolerance. In general, we find that in situ solar wind speed measurements near the ecliptic plane at solar minimum are extremely localised, being similar over only 1° or 2° of latitude. In the uniform polar fast wind above approximately 40° latitude at solar minimum, the latitudinal representivity error drops. At solar maximum, the increased variability of the solar wind speed at high latitudes means that the latitudinal representivity error increases at the poles, though becomes greater in the ecliptic, as long as moderate speed errors can be tolerated. The heliospheric magnetic field and solar wind density and temperature show very similar behaviour.

scholarly journals Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence model

2018 ◽  
Vol 8 ◽  
pp. A18 ◽  
Author(s):  
Manuela Temmer ◽  
Jürgen Hinterreiter ◽  
Martin A. Reiss
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
High Speed ◽  
Solar Wind Speed ◽  
Coronal Holes ◽  
In Situ Measurements ◽  
False Alarms ◽  
Wind Speed Profile ◽  
Persistence Model

We present a concept study of a solar wind forecasting method for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs) extracted from EUV data of STEREO and SoHO/SDO, we perform an uncertainty assessment derived from changes in the CHs and apply those changes to the predicted solar wind speed profile at 1 AU. We evaluate the method for the time period 2008–2012, and compare the results to a persistence model based on ACE in situ measurements and to the STEREO persistence model without implementing the information on CH evolution. Compared to an ACE based persistence model, the performance of the STEREO persistence model which takes into account the evolution of CHs, is able to increase the number of correctly predicted high-speed streams by about 12%, and to decrease the number of missed streams by about 23%, and the number of false alarms by about 19%. However, the added information on CH evolution is not able to deliver more accurate speed values for the forecast than using the STEREO persistence model without CH information which performs better than an ACE based persistence model. Investigating the CH evolution between STEREO and Earth view for varying separation angles over ∼25–140° East of Earth, we derive some relation between expanding CHs and increasing solar wind speed, but a less clear relation for decaying CHs and decreasing solar wind speed. This fact most likely prevents the method from making more precise forecasts. The obtained results support a future L5 mission and show the importance and valuable contribution using multi-viewpoint data.

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