We present results of global magnetohydrodynamic simulations which reconsider the relationship between the solar wind dynamic pressure (Pd) and magnetopause standoff distance (RSub). 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.
Simple Words Summation
The fresh new magnetopause ‘s the line between the near-World space, which is influenced of the magnetic job made in new Earth’s core, and you will interplanetary place inhabited from the plasma produced throughout the Sunshine called the solar piece of cake. Within this functions, i reexamine the partnership within magnetopause condition and you will variables regarding the fresh new solar power breeze as pc acting. It’s shown your relationship ranging from solar power breeze velocity and you may thickness and magnetopause condition is more cutting-edge than to begin with imagine.
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.
Has just, Nemecek et al. ( 2016 ) compared observed magnetopause crossings towards the Shue ainsi que al. model (Shue ainsi que al., 1997 ) getting half the final solar cycle and discovered health-related variations involving the design and observations. It contended the ionospheric conductivity additionally the solar breeze velocity is actually extra parameters that dictate brand new magnetopause position. Its statistical studies shows that an average magnetopause are farther off the planet than simply predicted through the day durations which have lower conductivity and you can large solar power piece of cake velocity. They advised that intensification of Ultraviolet radiation causes an increase throughout the magnetospheric-ionospheric currents one to reduces the magnetic tension for the magnetosphere and you may the magnetopause motions earthward. Quite the opposite, improvement of speed intensifies the newest viscous telecommunications within solar power wind and you can magnetosphere raising the international magnetospheric convection and you can getting way more magnetic flux into the dayside magnetosphere. We are going to speak about these types of presumptions below throughout the paper.