Playing with relatively short (20 min) big date periods involving the dynamic stress steps, i implicitly think that the alterations in the magnetopause reputation primarily result from the changes on solar wind stress and you will distinctions of your own dayside job-lined up Part 1 currents. Whilst the magnetotail most recent may have a slightly huge impulse go out, but in general they simply intensifies the end result of one’s Area step one most recent. grams., particular estimations have been made inside the Samso ); but not, (1) the brand new noncoupled MHD design hence results was presented over really does not replicate the new band most recent and (2) the time scale of your ring most recent intensification is usually much more than the step three–cuatro hour used in these types of simulations. We work of the paired habits below that is qualitatively much like the consequence of the noncoupled model, and this does not change our conclusions.
Ultimately, we need to evaluate several works to ensure which our results are design-separate. Dining table step 1 collects the power law indicator N from inside the (1) calculated of half a dozen products of about three around the world MHD models. The foremost is brand new noncoupled SWMF design whoever efficiency was indeed showed over. Plus the earliest works (Variation step one), we simulated around three most other items of a similar noncoupled design, a couple of with increased ionospheric conductivity and something which have a good dipole tip. New top-included Pedersen conductivity is thought as equal to 5 S in most the types, except products 2 and you will step three by which the fresh new integrated conductivity was ten and you will 100 S correspondingly. During the variation cuatro, i artificial the magnetosphere that have a good dipole tilt 31° . Alterations in N between Sizes step one and you may dos and Products step 1 and you can 4 is actually short, heated affairs and anywhere between Types step 1 and step three is reasonable, however, just for the brand new southward IMF. Remember that the ionospheric conductivity a hundred S is extremely higher and you may is going to be rarely observed in facts. I tell you they merely to show the fresh new role out-of conductivity because both times rise in conductivity inside the Adaptation dos transform Letter just for the velocity increase that have southward IMF.
A rise in the latest magnetotail current as well boost in the new Region step one currents weakens brand new magnetospheric magnetic industry and you can moves the brand new dayside magnetopause earthward
Variation 5 is short for works of SWMF design along with full inner-magnetosphere ionosphere, and you may Version six ‘s the LFM-Combine design. Per version, i generate four runs into the northward/southward IMF and for the density and you may velocity grows just like the informed me above (24 works in total). Recall you to definitely N=six regarding the most useful theoretical situation when your magnetopause status meets pressure harmony between the solar power breeze vibrant pressure together with Earth’s dipole occupation and you may Letter=six.6 in the empirical Shue et al. ( 1998 ) design. In reality, most of the received N try between those two values otherwise quite quicker. Five off half a dozen products expect N large or comparable to eight on runs toward thickness improve getting southward IMF. Whether or not Variation 5 predicts N smaller than eight, N are methodically higher in such a case for each design.
At the same time, Tsyganenko and you will Sibeck ( 1994 ) detailed your cross-end most recent as well as in a shorter training the fresh band newest along with the spot step 1 currents influence the new magnetized field towards magnetospheric area of the magnetopause
In addition to the comparison of different models, we investigate the influence of grid resolution on our results. We have calculated two runs for the same southward IMF with density and velocity changes using the noncoupled SWMF model with the 1/16 RE grid spacing around the subsolar magnetopause. We obtain different power laws, N=6.712 and 6.132, in the density and velocity runs, respectively (instead of 7.80 and 6.69 for the same model with a low resolution). Moreover, the normalized (to the solar wind electric field) reconnection rates in the low-resolution runs are smaller than those in the high-resolution runs (but are about the same in the density and velocity runs for the same resolution). We also find some differences in the CPCP and the magnetic field magnitude at geosynchronous orbit. We note that the grid resolution influences the magnitude of maximal electric current density at the magnetopause and possibly may change the total magnetopause current, but this problem requires more careful studies and it stays outside of the scope of the paper.