Magnetopause inflation under radial IMF: Comparison of models

Suvorova, A. V.; Дмитриев, А. В.

doi:10.1002/2014ea000084

Cited by 23 publications

(23 citation statements)

References 42 publications

(53 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The thickness of the magnetosheath also decreases in response to the radial IMF conditions as a result of expanded magnetopause [ Jelínek et al ., ]. The previous results show that the magnetopause moves about 2 R E sunward in comparison with the model predictions, having a bullet‐like or globally expanded structure [ Slavin et al ., ; Dušík et al ., ; Jelínek et al ., ; Suvorova et al ., , Suvorova and Dmitriev , , , Park et al ., ]. The magnetopause also shows a local time asymmetry in its size and shape [ Huang et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Evolution of the magnetic field structure outside the magnetopause under radial IMF conditions

Shue

Grygorov

et al. 2017

JGR Space Physics

View full text Add to dashboard Cite

We use the Time History of Events and Macroscale Interactions during Substorms data to investigate the magnetic field structure just outside the magnetopause and its time evolution for radial interplanetary magnetic field (IMF) events. When the magnetic field drapes around the magnetopause in the magnetosheath region, an asymmetric magnetic field orientation in different hemispheres is expected. Our two‐case study reveals some conflicts with the predicted draped field configuration in the Southern Hemisphere. The magnetosheath Bz component had a different sign depending on the upstream IMF Bx component's polarity at the beginning of the radial IMF intervals. With time, the observed Bz became northward in both cases with increasing positive values through the events. The increasing value of the Bz component may be explained by two possible mechanisms: by a change of the upstream IMF and by a reconnection between magnetosheath and magnetospheric field lines. Our study shows that both mechanisms contributed to the observed changes. Thus, there was a correlation between the change of the upstream IMF conditions and an increase in the magnetosheath northward magnetic field component. The observed formation of the boundary layer near the magnetopause proves that the reconnection process was ongoing at least for a part of the time. We suggest two possible reconnection scenarios: one near subsolar point and another tailward of the one cusp due to lobe reconnection. The asymmetry of reconnection locations causes rearrangement of the magnetic field structure near the magnetopause and turns the observed magnetosheath Bz component even further into positive values.

show abstract

Section: Introductionmentioning

confidence: 99%

Evolution of the magnetic field structure outside the magnetopause under radial IMF conditions

Shue

Grygorov

et al. 2017

JGR Space Physics

View full text Add to dashboard Cite

show abstract

“…Their results showed a systematic increase of observed magnetopause distances for radial IMF conditions, from ≃0.3 R E at 90° to ≃1.7 R E at 0° or 180° cone angles with respect to empirical models. Suvorova and Dmitriev [] inspected the ability of empirical magnetopause models to predict the magnetospheric expansion and found that only 4 out of 14 models, namely, Pudovkin et al [], Kuznetsov and Suvorova [], Suvorova et al [], and Lin et al [], could predict magnetopause positions for extremely low pressures and, hence, can be useful for quantitative estimation of the magnetospheric expansion under quasi‐radial IMF orientation.…”

Section: Introductionmentioning

confidence: 99%

A method to predict magnetopause expansion in radial IMF events by MHD simulations

et al. 2017

View full text Add to dashboard Cite

This paper presents a method for taking into account changes of solar wind parameters in the foreshock using global MHD simulations. We simulate four events with very distant subsolar magnetopause crossings that occurred during quasi‐radial interplanetary magnetic field (IMF) intervals lasting from one to several hours. Using previous statistical results, we suggest that the density and velocity in the foreshock cavity decrease to ∼60% and ∼94% of the ambient solar wind values when the IMF cone angle falls below 50°. This diminishes the solar wind dynamic pressure to 53% and causes a corresponding magnetospheric expansion. We change the upstream solar wind parameters in a global MHD model to take these foreshock effects into account. We demonstrate that the modified model predicts magnetopause distances during radial IMF intervals close to those observed by THEMIS. The strong total pressure decrease in the data seems to be a local, rather than a global, phenomenon. Although the simulations with decreased solar wind pressure generally reproduce the observed total pressure in the magnetosheath well, the total pressure in the magnetosphere often agrees better with results for nonmodified boundary conditions. The last result reveals a limitation of our method: we changed the boundary conditions along the whole inflow boundary, although a more correct approach would be to vary parameters only in the foreshock. A model with the suggested global modification of the boundary conditions better predicts the location of part of the magnetopause behind the foreshock but may fail in predicting the rest of the magnetopause.

show abstract

“…However, most of our knowledge about the magnetopause position comes from empirical models based on a large number of spacecraft crossings. Since Fairfield [], more than 15 empirical magnetopause models have been developed (14 of them mentioned in Suvorova and Dmitriev []) which define the magnetopause using different sets of observations. However, with only several exceptions [ Dmitriev and Suvorova , ; Wang et al , ; Shukhtina and Gordeev , ], all the empirical models made some a priori assumptions about the magnetopause shape.…”

Section: Introductionmentioning

confidence: 99%

Do we know the actual magnetopause position for typical solar wind conditions?

et al. 2016

View full text Add to dashboard Cite

We compare predicted magnetopause positions at the subsolar point and four reference points in the terminator plane obtained from several empirical and numerical MHD models. Empirical models using various sets of magnetopause crossings and making different assumptions about the magnetopause shape predict significantly different magnetopause positions (with a scatter >1 RE) even at the subsolar point. Axisymmetric magnetopause models cannot reproduce the cusp indentations or the changes related to the dipole tilt effect, and most of them predict the magnetopause closer to the Earth than nonaxisymmetric models for typical solar wind conditions and zero tilt angle. Predictions of two global nonaxisymmetric models do not match each other, and the models need additional verification. MHD models often predict the magnetopause closer to the Earth than the nonaxisymmetric empirical models, but the predictions of MHD simulations may need corrections for the ring current effect and decreases of the solar wind pressure that occur in the foreshock. Comparing MHD models in which the ring current magnetic field is taken into account with the empirical Lin et al. model, we find that the differences in the reference point positions predicted by these models are relatively small for Bz=0. Therefore, we assume that these predictions indicate the actual magnetopause position, but future investigations are still needed.

show abstract

Magnetopause inflation under radial IMF: Comparison of models

Cited by 23 publications

References 42 publications

Evolution of the magnetic field structure outside the magnetopause under radial IMF conditions

Evolution of the magnetic field structure outside the magnetopause under radial IMF conditions

A method to predict magnetopause expansion in radial IMF events by MHD simulations

Do we know the actual magnetopause position for typical solar wind conditions?

Contact Info

Product

Resources

About