Solar wind structure at 0.1-1 AU reconstructed from IPS observations using tomography

Kojima, M.; Asai, Kikuo; Hick, P. P.; Jackson, B. V.; Tokumaru, M.; Watanabe, Hironori; Yokobe, A.

doi:10.1063/1.51771

Cited by 5 publications

(5 citation statements)

References 8 publications

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“…Because of these limits, we generally present our analysis in the form of Carrington synoptic maps projected to a fixed heliocentric distance (to 1 AU, or to the solar surface). In this text we expand upon the results first presented by Kojima et al [1997] and Jackson et al [1997]. Other aspects of a tomographic analysis of the velocity data alone can be found in the work of Kojima et al [1998].…”

Section: Introductionmentioning

confidence: 72%

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Jackson¹,

Hick²,

Kojima³

et al. 1998

J. Geophys. Res.

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Abstract. We have produced a computer assisted tomography program that optimizes a three-dimensional model to fit observational data. We have used this program with interplanetary scintillation data from Nagoya, Japan, and Cambridge, England. The program iterates to a least squares solution fit of observed data using solar rotation and solar wind motion to provide perspective views of each point in space accessible to the observations. We plot the optimized model as Carrington maps in velocity V and density N e for the two data sets with resolutions of 10 ø in hellographic longitude and latitude. We map the model to 1 AU and compare this to in situ observations from the IMP spacecraft. Tomography methods can be used to improve upon the inherent averages made in the point P approximation used to display heliospheric data. IPS observations covering a large range of solar elongations and obtained over an extended period of time provide a global view of the inner heliosphere. The multiple perspectives required for tomographic analysis are provided by both solar rotation and outward solar wind motion. Effects due to the evolution of solar structures as they rotate during the period of observation can be minimized by selecting observations from a quiet part of the solar cycle. From this comparison we find12,049

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Section: Introductionmentioning

confidence: 72%

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Jackson¹,

Hick²,

Kojima³

et al. 1998

J. Geophys. Res.

Self Cite

179

172

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“…These observations show a predominance of disturbances that corotate with the Sun as inferred from a list of events and their associations [ Hewish and Bravo , 1986]. Three‐dimensional results from IPS observations recorded over a wide range of elongations were obtained by least squares fitting to a heliospheric model incorporating both outward solar wind flow and solar rotation [ Jackson et al , 1997; Kojima et al , 1997; Jackson et al , 1998; Kojima et al , 1998; Asai et al , 1998]. In the 3‐D models derived from IPS analysis, scintillation strength serves as a proxy for density.…”

Section: Smei Analysis Techniquesmentioning

confidence: 99%

Preliminary three‐dimensional analysis of the heliospheric response to the 28 October 2003 CME using SMEI white‐light observations

et al. 2006

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[1] The Solar Mass Ejection Imager (SMEI) has recorded the inner heliospheric response in white-light Thomson scattering to the 28 October 2003 coronal mass ejection (CME). This preliminary report shows the evolution of this particular event in SMEI observations, as we track it from a first measurement at approximately 20°elongation (angular distance) from the solar disk until it fades in the antisolar hemisphere in the SMEI 180°field of view. The large angle and spectrometric coronagraph (LASCO) images show a CME and an underlying bright ejection of coronal material that is associated with an erupting prominence. Both of these are seen by SMEI in the interplanetary medium. We employ a three-dimensional (3-D) reconstruction technique that derives its perspective views from outward flowing solar wind to reveal the shape and extent of the CME. This is accomplished by iteratively fitting the parameters of a kinematic solar wind density model to both SMEI white-light observations and Solar-Terrestrial Environment Laboratory (STELab), interplanetary scintillation (IPS) velocity data. This modeling technique separates the true heliospheric signal in SMEI observations from background noise and reconstructs the 3-D heliospheric structure as a function of time. These reconstructions allow separation of the 28 October CME from other nearby heliospheric structure and a determination of its mass. The present results are the first utilizing this type of 3-D reconstruction with the SMEI data. We determine an excess-over-ambient mass for the southward moving ejecta associated with the prominence material of 7.1 Â 10 16 g and a total mass of 8.9 Â 10 16 g. Preliminary SMEI white-light calibration indicates that the total mass of this CME including possible associated nearby structures may have been as much as $2.0 Â 10 17 g spread over much of the earthward facing hemisphere.

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“…These models have ambiguities and result in CME arrival-time errors because the interactions between background solar wind and CMEs can affect the propagation of CMEs (e.g., Chen 1996;Vršnak and Gopalswamy 2002). Background solar wind velocity can also be derived from IPS observations using the tomography technique (Kojima et al 1998;Jackson et al 1998), and the derived velocity distribution can be adopted as the inner boundary of the global MHD simulation (Jackson et al 2015). In future modeling efforts, we may rst derive background solar wind velocity distribution from IPS data using the tomography technique, in which transient phenomena such as CMEs are less prominent because the tomography of the background solar wind requires at least several days of IPS data.…”

Section: Causes Of the Arrival-time Errormentioning

confidence: 99%

Validation of Coronal Mass Ejection Arrival-Time Forecasts by Magnetohydrodynamic Simulations based on Interplanetary Scintillation Observations

Iwai

Shiota²,

Tokumaru

et al. 2020

Preprint

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Coronal mass ejections (CMEs) cause various disturbances of the space environment; therefore, forecasting their arrival time is very important. However, forecasting accuracy is hindered by limited CME observations in interplanetary space. This study investigates the accuracy of CME arrival times at the Earth forecasted by three-dimensional (3D) magnetohydrodynamic (MHD) simulations based on interplanetary scintillation (IPS) observations. In this system, CMEs are approximated as spheromaks with various initial speeds. Ten MHD simulations with different CME initial speed are tested, and the density distributions derived from each simulation run are compared with IPS data observed by the Institute for Space-Earth Environmental Research (ISEE), Nagoya University. The CME arrival time of the simulation run that most closely agrees with the IPS data is selected as the forecasted time. We then validate the accuracy of this forecast using 12 halo CME events. The average absolute arrival-time error of the IPS-based MHD forecast is approximately 5.0 h, which is one of the most accurate predictions that ever been validated, whereas that of MHD simulations without IPS data, in which the initial CME speed is derived from white-light coronagraph images, is approximately 6.7 h. This suggests that the assimilation of IPS data into MHD simulations can improve the accuracy of CME arrival-time forecasts. The average predicted arrival times are earlier than the actual arrival times. These early predictions may be due to overestimation of the magnetic field included in the spheromak and/or underestimation of the drag force from the background solar wind, the latter of which could be related to underestimation of CME size or background solar wind density.

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Solar wind structure at 0.1-1 AU reconstructed from IPS observations using tomography

Cited by 5 publications

References 8 publications

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Preliminary three‐dimensional analysis of the heliospheric response to the 28 October 2003 CME using SMEI white‐light observations

Validation of Coronal Mass Ejection Arrival-Time Forecasts by Magnetohydrodynamic Simulations based on Interplanetary Scintillation Observations

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