Physics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsm51b2091s&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #SM51B-2091
Physics
[2700] Magnetospheric Physics, [2744] Magnetospheric Physics / Magnetotail, [2790] Magnetospheric Physics / Substorms
Scientific paper
The signature of plasma sheet and embedded current sheet thinning is an increase in magnetic pressure, and such thinning is known as a precusor to substorm onset in the magnetotail. One of the critical and unanswered questions is how global magnetospheric convection leads to the evolution of the tail plasma sheet, resulting in the formation of a weak field region and a near-Earth neutral line at X=-10 to -30 Re. Using multi-spacecraft observations during substorms by THEMIS, we investigated flux tube evolution in the plasma sheet before substorm onsets and observed two distinct types of the flux tube changes. The study on a small substorm event on April 8 2009, showed that the thinning can occur with constant density and total pressure in the plasma sheet. This new type of flux tube change is found to be common for most non-storm time substorms. On the other hand, for a large storm-time substorm on April 5, 2010, the total pressure in the magnetotail increases gradually during the period of enhanced solar wind dynamic pressure and strong southward IMF. The increases in both the density and plasma pressure are consistent with the compression of the plasma in the flux tubes under increased lobe field strength. However about 10 min before the substorm onset, the compression signature ceased and we observed the signatures of incompressible cross-tail current sheet thinning. We conclude that the increased lobe field strength is not the necessary and primary cause for cross tail current sheet thinning but rather thinning can occur within the plasma sheet as a result of unknown internal processes. We emphasize that the presence of the incompressible thinning before substorm onset provides an explanation for the formation of the near-Earth neutral line and the development of the high beta regions as a result of the thinning.
Fairfield Donald H.
Le Guan
Saito Masa-Hiko
No associations
LandOfFree
Incompressible cross-tail current sheet thinning observed by THEMIS does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Incompressible cross-tail current sheet thinning observed by THEMIS, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Incompressible cross-tail current sheet thinning observed by THEMIS will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1891523