Inclusion of In-Situ Velocity Measurements into the UCSD Time-Dependent Tomography to Constrain and Better-Forecast Remote-Sensing Observations

Jackson, B. V.; Hick, P. P.; Bisi, M. M.; Clover, J. M.; Buffington, A.

doi:10.1007/s11207-010-9529-0

Cited by 26 publications

(28 citation statements)

References 27 publications

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“…The result is a better determined prediction of the change from current in situ plasma conditions. Additionally, we found [ Jackson et al ., ] that this provided a globally more uniform time‐dependent reconstruction. Considering a column extending from the sub‐Earth point on the Sun to the Earth, the results match in situ values of velocity and density well, all the while maintaining the kinematic mass and mass flux conservation.…”

Section: Tomographic Analysis and Field Extrapolation Using A Sample mentioning

confidence: 99%

“…IPS data used in the present paper are from the Solar Terrestrial Environment Laboratory (STELab), now called the Institute for Space‐Earth Environmental Research (ISEE), Japan [ Kojima and Kakinuma , ]. To further refine these results, the analyses are fit to near‐Earth in situ measurements of plasma velocities and densities [ Jackson et al ., , ]. Global heliospheric results are calculated for Carrington rotation time intervals (27 days).…”

Section: Introductionmentioning

confidence: 99%

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Exploration of solar photospheric magnetic field data sets using the UCSD tomography

Jackson

Buffington

et al. 2016

Space Weather

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This article investigates the use of two different types of National Solar Observatory magnetograms and two different coronal field modeling techniques over 10 years. Both the “open‐field” Current Sheet Source Surface (CSSS) and a “closed‐field” technique using CSSS modeling are compared. The University of California, San Diego, tomographic modeling, using interplanetary scintillation data from Japan, provides the global velocities to extrapolate these fields outward, which are then compared with fields measured in situ near Earth. Although the open‐field technique generally gives a better result for radial and tangential fields, we find that a portion of the closed extrapolated fields measured in situ near Earth comes from the direct outward mapping of these fields in the low solar corona. All three closed‐field components are nonzero at 1 AU and are compared with the appropriate magnetometer values. A significant positive correlation exists between these closed‐field components and the in situ measurements over the last 10 years. We determine that a small fraction of the static low‐coronal component flux, which includes the Bn (north‐south) component, regularly escapes from closed‐field regions. The closed‐field flux fraction varies by about a factor of 3 from a mean value during this period, relative to the magnitude of the field components measured in situ near Earth, and maximizes in 2014. This implies that a relatively more efficient process for closed‐flux escape occurs near solar maximum. We also compare and find that the popular Potential Field Source Surface and CSSS model closed fields are nearly identical in sign and strength.

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Section: Tomographic Analysis and Field Extrapolation Using A Sample mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploration of solar photospheric magnetic field data sets using the UCSD tomography

Jackson

Buffington

et al. 2016

Space Weather

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“…Early considerations using IPS observations led us to develop an analysis tool that directly addresses the LOS problem for IPS measurements in order to locate heliospheric structures in 3D (Jackson et al 1998(Jackson et al , 2003Jackson et al 2010Jackson et al , 2011. This tool explicitly takes into account the 3D extent of heliospheric structures, including the fact that the greatest contribution is from material closest to the Sun, but without any explicit assumption about the distribution of velocity and density along these lines of sight.…”

Section: Analysis Techniquesmentioning

confidence: 99%

“…Best fit is achieved iteratively: when the modeled 3D solar wind at a large solar distance does not match the overall observations, the source surface values are altered to minimize the deviations. These global heliospheric analyses also iteratively match hour-averaged in situ data at Earth to provide a normalization of the two parameters that are mapped globally in the solar wind (Jackson et al 2010(Jackson et al , 2013. Figure 2 is an example of the Carrington-rotation interval 2056 (CR2056) velocity at Earth from our 3D reconstruction analysis using STELab IPS data from 2007 April and May.…”

Section: Analysis Techniquesmentioning

confidence: 99%

A Determination of the North–south Heliospheric Magnetic Field Component From Inner Corona Closed-Loop Propagation

Jackson

Hick

Buffington

et al. 2015

ApJ

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A component of the magnetic field measured in situ near the Earth in the solar wind is present from north-south fields from the low solar corona. Using the Current-sheet Source Surface model, these fields can be extrapolated upward from near the solar surface to 1 AU. Global velocities inferred from a combination of interplanetary scintillation observations matched to in situ velocities and densities provide the extrapolation to 1 AU assuming mass and mass flux conservation. The north-south field component is compared with the same ACE in situ magnetic field component-the Normal (Radial Tangential Normal) Bn coordinate-for three years throughout the solar minimum of the current solar cycle. We find a significant positive correlation throughout this period between this method of determining the Bn field compared with in situ measurements. Given this result from a study during the latest solar minimum, this indicates that a small fraction of the low-coronal Bn component flux regularly escapes from closed field regions. The prospects for Space Weather, where the knowledge of a Bz field at Earth is important for its geomagnetic field effects, is also now enhanced. This is because the Bn field provides the major portion of the Geocentric Solar Magnetospheric Bz field coordinate that couples most closely to the Earth's geomagnetic field.

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“…As an alternative, in Bisi et al (2013) remote-sensing radio observatios of Interplanetary Scintillation (IPS) are used to probe the inner heliosphere and to identify density irregularities in the solar wind. When enhanced by the UCSD timedependent tomography technique (Jackson et al, 2010). Harrison et al (2017) provides an extensive review on how heliospheric imaging can be used to improve our space weather forecasts.…”

Section: Introductionmentioning

confidence: 99%

A new technique for observationally derived boundary conditions for space weather

Pagano

Mackay

Yeates

2018

J. Space Weather Space Clim.

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-Context. In recent years, space weather research has focused on developing modelling techniques to predict the arrival time and properties of coronal mass ejections (CMEs) at the Earth. The aim of this paper is to propose a new modelling technique suitable for the next generation of Space Weather predictive tools that is both efficient and accurate. The aim of the new approach is to provide interplanetary space weather forecasting models with accurate time dependent boundary conditions of erupting magnetic flux ropes in the upper solar corona. Methods. To produce boundary conditions, we couple two different modelling techniques, MHD simulations and a quasi-static non-potential evolution model. Both are applied on a spatial domain that covers the entire solar surface, although they extend over a different radial distance. The non-potential model uses a time series of observed synoptic magnetograms to drive the non-potential quasi-static evolution of the coronal magnetic field. This allows us to follow the formation and loss of equilibrium of magnetic flux ropes. Following this a MHD simulation captures the dynamic evolution of the erupting flux rope, when it is ejected into interplanetary space. Results.The present paper focuses on the MHD simulations that follow the ejection of magnetic flux ropes to 4 R ⊙ . We first propose a technique for specifying the pre-eruptive plasma properties in the corona. Next, time dependent MHD simulations describe the ejection of two magnetic flux ropes, that produce time dependent boundary conditions for the magnetic field and plasma at 4 R ⊙ that in future may be applied to interplanetary space weather prediction models. Conclusions. In the present paper, we show that the dual use of quasi-static non-potential magnetic field simulations and full time dependent MHD simulations can produce realistic inhomogeneous boundary conditions for space weather forecasting tools. Before a fully operational model can be produced there are a number of technical and scientific challenges that still need to be addressed. Nevertheless, we illustrate that coupling quasi-static and MHD simulations in this way can significantly reduce the computational time required to produce realistic space weather boundary conditions.

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Inclusion of In-Situ Velocity Measurements into the UCSD Time-Dependent Tomography to Constrain and Better-Forecast Remote-Sensing Observations

Cited by 26 publications

References 27 publications

Exploration of solar photospheric magnetic field data sets using the UCSD tomography

Exploration of solar photospheric magnetic field data sets using the UCSD tomography

A Determination of the North–south Heliospheric Magnetic Field Component From Inner Corona Closed-Loop Propagation

A new technique for observationally derived boundary conditions for space weather

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