Magnetotail and substorms
Journal Article
·
· Space Sci. Rev., v. 15, no. 2/3, pp. 205-266
The tail plays a very active and important role in substorms. Magnetic flux eroded from the dayside magnetosphere is stored here. As more and more flux is transported to the magnetotail and stored, the boundary of the tail flares more, the field strength in the sail increases, and the currents strengthen and move closer to the Earth. Further, the plasma sheet thins and the magnetic flux crossing the neutral sheet lessens. At the onset of the expansion phase, the stored magnetic flux is returned from the tail and energy is deposited in the magnetosphere and ionosphere. During the expansion phase of isolated substorms, the flaring angle and the lobe field strength decrease, the plasma sheet thickens and more magnetic flux crosses the neutral sheet. In this review, the experimental evidence for these processes are discussed and a phenomenological or qualitative model of the substorm sequence is presented. In this model, the flux transport is driven by the merging of the magnetospheric and interplanetary magnetic fields. During the growth phase of substorms the merging rate on the dayside magnetosphere exceeds the reconnection rate in the neutral sheet. In order to remove the oversupply of magnetic flux in the tail, a neutral point forms in the near Earth portion of the tail. If the new reconnection rate exceeds the dayside merging rate, then an isolated substorm results. However, a situation can occur in which dayside merging and tail reconnection are in equilibrium. The observed polar cap electric fleld and its correlation with the interplanetary magnetic fleld is found to be in accord with open magnetospheric models. (auth)
- Research Organization:
- Univ. of California, Los Angeles
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-019338
- OSTI ID:
- 4334249
- Journal Information:
- Space Sci. Rev., v. 15, no. 2/3, pp. 205-266, Journal Name: Space Sci. Rev., v. 15, no. 2/3, pp. 205-266; ISSN SPSRA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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