We present results of global magnetohydrodynamic simulations which reconsider the relationship between the solar wind dynamic pressure (Pd) and magnetopause standoff distance (RSandwich). We simulate the magnetospheric response to increases in the dynamic pressure by varying separately the solar wind density or velocity for northward and southward interplanetary magnetic field (IMF). We obtain different values of the power law indices N in the relation depending on which parameter, density, or velocity, has been varied and for which IMF orientation. The changes in the standoff distance are smaller (higher N) for a density increase for southward IMF and greater (smaller N) for a velocity increase.
Basic Language Conclusion
The fresh magnetopause ‘s the line amongst the near-World room, that is influenced of the magnetic industry built in new Planet’s key, and you will interplanetary place inhabited by the plasma produced regarding Sunrays called the solar power snap. Contained in this work, we reexamine the relationship amongst the magnetopause standing and you will details away from new solar snap in the shape of computer system acting. It is revealed that relationship ranging from solar power snap acceleration and you will thickness and you can magnetopause reputation is far more state-of-the-art than originally consider.
step 1 Inclusion
The magnetopause is one of principal magnetospheric boundaries which separates dense solar wind plasma in the magnetosheath and tenuous and hot magnetospheric plasma. In response to strong solar wind pressure pulses, the magnetopause comes closer to the Earth and geosynchronous spacecraft may exit the magnetosphere and cross the magnetosheath in the subsolar region or even enter into the supersonic solar wind. To date, more than 15 empirical models of the magnetopause have been developed based on a great number of magnetopause crossings under different solar wind conditions (a list of 14 models published by Suvorova & Dmitriev, 2015 ). Chapman and Ferraro ( 1931 ) suggested that the magnetopause location can be determined from the pressure balance condition between the solar wind dynamic pressure (Pd) and the magnetic pressure of the Earth’s dipole. Besides the dynamic pressure, the second important solar wind parameter influencing the magnetopause position is the interplanetary magnetic field (IMF) Bz component (Aubry et al., 1970 ; Fairfield, 1971 ). A strong southward IMF (Bz<0) results in magnetic reconnection at the dayside magnetopause and intensification of the large-scale field-aligned (Region 1) currents connecting the magnetosphere and ionosphere and moving the magnetopause closer to the Earth (Hill & Rassbach, 1975 ; Sibeck, 1994 ). The Pd and Bz are the only two input parameters in several popular magnetopause models (e.g., Petrinec & Russell, 1996 ; Roelof & Sibeck, 1993 ; Shue et al., 1997 ; 1998 ; Sibeck et al., 1991 ). The recent (Lin et al., 2010 ) empirical model replaces the solar wind dynamic pressure by the sum of dynamic and magnetic pressures and takes into account the Earth’s dipole tilt. Moreover, several papers (Dusik et al., 2010 ; Grygorov et al., 2017 ; Merka et al., 2003 ; Samso ) note that the magnetopause significantly expands during radial IMF intervals concluding that the IMF cone angle (the angle between IMF and the Sun-Earth line) eter for calculation of the magnetopause location.
Recently, Nemecek ainsi que al. ( 2016 ) opposed observed magnetopause crossings to your Shue et al. model (Shue et al., 1997 ) to possess 1 / 2 of the final solar power period and found medical distinctions within model and you can findings. They argued that the ionospheric conductivity therefore the solar power snap acceleration try a lot more variables you to definitely influence the fresh magnetopause updates. Its analytical study suggests that the typical magnetopause was further away from the planet than just predicted while in the date periods with lower conductivity and high solar power cinch acceleration. It advised one intensification out of Ultraviolet rays contributes to a growth throughout the magnetospheric-ionospheric currents one to decreases the magnetized tension inside magnetosphere and you may the fresh new magnetopause motions earthward. Quite the opposite, improvement of one’s speed intensifies the brand new viscous telecommunications within solar power snap and magnetosphere raising the worldwide magnetospheric convection and bringing more magnetic numer telefonu flirthookup flux toward dayside magnetosphere. We’re going to explore these types of presumptions less than throughout the papers.