Effect of the ambient solar wind speed on drag-based CME prediction accuracy

In the last years, many kinds of CME models, based on a drag-based evolution through interplanetary space, have been developed and are now widely used by the community. The unbeatable advantage of those methods is that they are computationally cheap and are therefore suitable to be used as ensemble models. Additionally, their prediction accuracy is absolutely comparable to more sophisticated models.The ELlipse Evolution model based on heliospheric imager (HI) observations (ELEvoHI) assumes an elliptic frontal shape within the ecliptic plane and allows the CME to adjust to the ambient solar wind speed, i.e. it is drag-based. ELEvoHI is used as an ensemble simulation by varying the CME frontal shape within given boundary values. The results include a frequency distribution of predicted arrival time and arrival speed and an estimation of the arrival probability.In this study, we investigate the possibility of not only varying the parameters related to the CME's ecliptic extent but also the ambient solar wind speed for each CME ensemle member. Although we have used a range of +/-100 km/s for possible values of the solar wind speed in the past, only the best candidate was in the end used to contribute to the prediction.&#160;We present the results of this approach by applying it to a CME propagating in a highly structured solar wind and compare the frequency distribution of the arrival time and speed predictions to those of the usual ELEvoHI approach.

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CME arrival time predictions with a deformable front

10.5194/egusphere-egu21-5830 ◽

2021 ◽

Author(s):

Jürgen Hinterreiter ◽

Tanja Amerstorfer ◽

Martin A. Reiss ◽

Andreas J. Weiss ◽

Christian Möstl ◽

...

Keyword(s):

Solar Wind ◽

Large Scale ◽

Arrival Time ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Model Combination ◽

First Results ◽

Good Agreement ◽

Ambient Solar Wind

We present the first results of our newly developed CME arrival prediction model, which allows the CME front to deform and adapt to the changing solar wind conditions.&#160;Our model is based on ELEvoHI and makes use of the WSA/HUX (Wang-Sheeley-Arge/Heliospheric Upwind eXtrapolation) model combination, which computes large-scale ambient solar wind conditions in the interplanetary space. With an estimate of the solar wind speed and density, we are able to account for the drag exerted on different parts of the CME front.&#160;Initially, our model relies on heliospheric imager observations to confine an elliptical CME front and to obtain an initial speed and drag parameter for the CME. After a certain distance, each point of the CME front is propagating based on the conditions in the heliosphere. In this case study, we compare our results to previous arrival time predictions using ELEvoHI with a rigid CME front. We find that the actual arrival time at Earth and the arrival time predicted by the new model are in very good agreement.

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CME arrival prediction and its dependency on input data and model parameters

10.5194/egusphere-egu2020-4703 ◽

2020 ◽

Author(s):

Tanja Amerstorfer ◽

Jürgen Hinterreiter ◽

Martin A. Reiss ◽

Maike Bauer ◽

Christian Möstl ◽

...

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Real Time ◽

Arrival Time ◽

Solar Wind Speed ◽

Model Parameters ◽

The Sun ◽

Model Set ◽

Different Sources ◽

Ambient Solar Wind

During the last years, we focused on developing a prediction tool that utilizes the wide-angle observations of STEREO's heliospheric imagers. The unsurpassable advantage of these imagers is the possibility to observe the evolution and propagation of a coronal mass ejection (CME) from close to the Sun up to 1 AU and beyond. We believe that using this advantage instead of relying on coronagraph observations that are limited to observe only 14% of the Sun-Earth line, it is possible to improve today's CME arrival time predictions. The ELlipse Evolution model based on HI observations (ELEvoHI) assumes an elliptic frontal shape within the ecliptic plane and allows the CME to adjust to the ambient solar wind speed, i.e. it is drag-based. ELEvoHI is used as an ensemble simulation by varying the CME frontal shape within given boundary values. The results include a frequency distrubution of predicted arrival time and arrival speed and an estimation of the arrival probability. ELEvoHI can be operated using several kinds of inputs. In this study we investigate 15 well-defined single CMEs when STEREO was around L4/5 between the end of 2009 and the beginning of 2011. Three different sources of input propagation directions (and shapes) are used together with three different sources of ambient solar wind speed and two different ways of defining the most appropriate fit to the HI data. The combination of these different approaches and inputs leads to 18 different model set-ups used to predict each of the 15 events in our list leading to 270 ELEvoHI ensemble predictions and all in all to almost 60000 runs. To identify the most suitable and most accurate model set-up to run ELEvoHI, we compare the predictions to the actual in situ arrival of the CMEs. This model is specified for using data from future space weather missions carrying HIs located at L5 or L1 and can also directly be used together with STEREO-A near real-time HI beacon data to provide real-time CME arrival predictions during the next 7 years when STEREO-A is observing the Sun-Earth space.

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The role of aerodynamic drag in dynamics of coronal mass ejections

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309029391 ◽

2008 ◽

Vol 4 (S257) ◽

pp. 271-277

Author(s):

Bojan Vršnak ◽

Dijana Vrbanec ◽

Jaša Čalogović ◽

Tomislav Žic

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Coronal Mass Ejections ◽

Weather Forecasting ◽

Aerodynamic Drag ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Standard Form ◽

The Sun

AbstractDynamics of coronal mass ejections (CMEs) is strongly affected by the interaction of the erupting structure with the ambient magnetoplasma: eruptions that are faster than solar wind transfer the momentum and energy to the wind and generally decelerate, whereas slower ones gain the momentum and accelerate. Such a behavior can be expressed in terms of “aerodynamic” drag. We employ a large sample of CMEs to analyze the relationship between kinematics of CMEs and drag-related parameters, such as ambient solar wind speed and the CME mass. Employing coronagraphic observations it is demonstrated that massive CMEs are less affected by the aerodynamic drag than light ones. On the other hand, in situ measurements are used to inspect the role of the solar wind speed and it is shown that the Sun-Earth transit time is more closely related to the wind speed than to take-off speed of CMEs. These findings are interpreted by analyzing solutions of a simple equation of motion based on the standard form for the drag acceleration. The results show that most of the acceleration/deceleration of CMEs on their way through the interplanetary space takes place close to the Sun, where the ambient plasma density is still high. Implications for the space weather forecasting of CME arrival-times are discussed.

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Forecasting the Ambient Solar Wind with Numerical Models. II. An Adaptive Prediction System for Specifying Solar Wind Speed near the Sun

The Astrophysical Journal ◽

10.3847/1538-4357/ab78a0 ◽

2020 ◽

Vol 891 (2) ◽

pp. 165 ◽

Cited By ~ 1

Author(s):

Martin A. Reiss ◽

Peter J. MacNeice ◽

Karin Muglach ◽

Charles N. Arge ◽

Christian Möstl ◽

...

Keyword(s):

Solar Wind ◽

Wind Speed ◽

Numerical Models ◽

Solar Wind Speed ◽

The Sun ◽

Prediction System ◽

Adaptive Prediction ◽

Ambient Solar Wind

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ANALISIS KONDISI FLUKS ELEKTRON DI SABUK RADIASI ELEKTRON LUAR BERDASARKAN MEDAN MAGNET ANTARPLANET (BZ) DAN KECEPATAN ANGIN MATAHARI (ANALYSIS OF ELECTRON FLUX CONDITION IN OUTER ELECTRON RADIATION BELT BASED ON INTERPLANETARY MAGNETIC FIELD (BZ) AND SOL

Jurnal Sains Dirgantara ◽

10.30536/j.jsd.2017.v15.a2738 ◽

2018 ◽

Vol 15 (1) ◽

pp. 39

Author(s):

Siska Filawati

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Wind Speed ◽

Radiation Belt ◽

Solar Wind Velocity ◽

Electron Flux ◽

Interplanetary Space ◽

Solar Wind Speed ◽

Electron Radiation ◽

Outer Electron

Interplanetary space is a hazard precursor for solar eruption toward earth. The solar eruptions enhance electron flux that can lead to anomalies, shifts, and permanent damage to spacecraft, e.g. satellites. The data used in this paper are interplanetary space data represented by interplanetary magnetic field (Bz) and solar wind speed, as well as Dst and AE indexes as comparison indicating disturbance has reached Earth’s poles and equator during 2011-2012. The method used is to determine the value of maximum and minimum Bz in the year 2011-2012 which is taken five days before and after. Analysis and calculation of correlation is done to data of Bz-electron flux and solar wind velocity-electron flux. Clarification of disturbence in interplanetary space and outer electron radiation belt is using index data Dst and AE indexes are used to clarify interplanetary space and outer electron radiation belt disturbances. The aim of this study is to determine the characteristics of interplanetary space that can increase the electron flux so that the space weather early warning can be done. It was found that the period of electron flux enhancement after decrease and increase of Bz was 2 to 3 days. The electron flux would enhance when interplanetary space was in its normal condition at solar wind speed 500 km/sec and Bz is -5 nT to +5 nT. Electron flux correlation with solar wind velocity was better than with Bz. ABSTRAKKondisi ruang antarplanet merupakan prekursor bahaya erupsi matahari terhadap bumi. Erupsi matahari dapat menyebabkan peningkatan fluks elektron. Tingginya fluks elektron dapat menyebabkan anomali, pergeseran, dan kerusakan permanen pada wahana antariksa, misal satelit. Data yang digunakan pada makalah ini adalah data ruang antarplanet yang diwakili oleh kondisi medan magnet antarplanet (Bz) dan kecepatan angin matahari yang merupakan prekursor peningkatan fluks elektron serta data indeks Dst dan indeks AE sebagai pembanding bahwa gangguan telah mencapai kutub dan ekuator bumi selama rentang waktu 2011-2012. Metode yang digunakan adalah menentukan nilai Bz maksimum dan minimum dalam tahun 2011-2012 yang selanjutnya dari penanggalan data tersebut diambil data lima hari sebelum dan sesudah. Analisis dan perhitungan korelasi dilakukan terhadap data Bz-fluks elektron dan kecepatan angin matahari-fluks elektron. Klarifikasi gangguan yang terjadi di ruang antarplanet dan sabuk radiasi elektron luar menggunakan data indeks Dst dan indeks AE. Tujuan ditulisnya makalah ini adalah untuk mengetahui karakteristik kondisi ruang antarplanet yang dapat meningkatkan fluks elektron agar peringatan dini cuaca antariksa dapat dilakukan. Hasil yang didapatkan adalah waktu yang dibutuhkan fluks elektron setelah terjadi penurunan dan peningkatan Bz adalah 2 hingga 3 hari, fluks elektron akan meningkat saat kondisi ruang antarplanet normal yaitu pada kecepatan 500 km/detik dan Bz -5 nT hingga +5 nT, korelasi fluks elektron dengan kecepatan angin matahari lebih baik dibanding fluks elektron dengan Bz.

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Prediction of CME arrivals; differences based on stereoscopic heliospheric imager data

10.5194/egusphere-egu2020-7829 ◽

2020 ◽

Author(s):

Jürgen Hinterreiter ◽

Tanja Amerstorfer ◽

Martin A. Reiss ◽

Manuela Temmer ◽

Christian Möstl ◽

...

Keyword(s):

Solar Wind ◽

Arrival Time ◽

Ecliptic Plane ◽

Essential Factor ◽

Arrival Times ◽

Event Prediction ◽

Vantage Points ◽

Ambient Solar Wind ◽

Heliospheric Imager

Forecasting the arrival time and speed of CMEs is of high importance. However, uncertainties in the forecasts are high. We present the results of post-event prediction of CME arrivals using ELEvoHI (ELlipse Evolution model based on Heliospheric Imager observations) ensemble modeling. The model uses time-elongation profiles provided by HI (Heliospheric Imager) onboard STEREO (Solar TErrestrial RElations Observatory) and assumes an elliptical shape of the CME front. The drag force exerted by the ambient solar wind is an essential factor influencing the dynamic evolution of CMEs in the heliosphere. To account for this effect, ELEvoHI utilizes the modeled ambient solar wind provided by the Wang-Sheeley-Arge model. We carefully select 12 CMEs between February 2010 and July 2012, which show clear signatures in STEREO-A and STEREO-B HI images, have a corresponding in-situ signature, and propagate close to the ecliptic plane. As input to ELEvoHI, we make use of STEREO-A and STEREO-B time-elongation profiles for each CME and compare the predicted arrival times and speeds based on both vantage points with each other. We present our model results and discuss possible reasons for the differences in the arrival times of up to 15 hours.

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