We present results of global magnetohydrodynamic simulations which reconsider the relationship between the solar wind dynamic pressure (P_d) and magnetopause standoff distance (R_Sub). 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 Words Conclusion

The newest magnetopause is the border amongst the close-Planet area, that’s governed because of the magnetic industry built in the fresh new Earth’s key, and interplanetary room populated by plasma produced from the Sunlight called the solar power wind. Inside works, i reexamine the relationship involving the magnetopause updates and variables out-of the solar power breeze by means of desktop acting. It’s found the dating ranging from solar power snap speed and you may thickness and you will magnetopause reputation is more state-of-the-art than originally envision.

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 (P_d) 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) B_z component (Aubry et al., 1970 ; Fairfield, 1971 ). A strong southward IMF (B_z<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 P_d and B_z 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 et al. ( 2016 ) opposed observed magnetopause crossings on Shue et al. design (Shue et al., 1997 ) to possess half of the past solar power years and found logical variations involving the model and you will observations. It argued that ionospheric conductivity and solar power breeze speed was additional parameters you to definitely influence the fresh magnetopause position. The analytical data signifies that the typical magnetopause is farther of the planet than simply forecast throughout time intervals which have straight down conductivity and you will higher solar snap velocity. They ideal one intensification away from Ultraviolet radiation results in a growth regarding the magnetospheric-ionospheric currents one reduces the magnetic https://datingranking.net/pl/her-dating-recenzja/ stress during the magnetosphere and this new magnetopause actions earthward. To the contrary, improvement of velocity intensifies the newest viscous telecommunications between your solar power snap and you can magnetosphere improving the all over the world magnetospheric convection and you may providing a great deal more magnetized flux into the dayside magnetosphere. We will talk about these assumptions less than regarding the report.