Details

Autor(en) / Beteiligte

• Sun, Weiqin
• Sadeghzadeh, Sina
• Yang, Jian
• Wang, Wenrui
• Cui, Jun

Titel

Development of Multiple Injection Channels During a Sawtooth Substorm Event

Ist Teil von

• Geophysical research letters, 2021-07, Vol.48 (13), p.n/a

Erscheinungsjahr

2021

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• Substorm injection boundary was proposed to explain the dispersion characteristics of particles during the substorm expansion phase. Sawtooth event, a peculiar quasi‐periodic type of substorms, is believed to have a very wide injection boundary around the geosynchronous orbit. In this study, we combine the numerical simulation of the Rice Convection Model with the IMAGE, LANL, and GOES data to investigate how the injection develops and couples with the ionosphere during a sawtooth substorm. We find the wide injection breaks up into multiple injection boundaries/channels with the local time separation of about 1–2 h. Using backward tracing of energetic particles in the self‐consistently computed electromagnetic field, we can infer the MLT locations of the channels, which are found to be nearly one‐to‐one co‐located with multiple finger‐like auroral structures. Our study provides strong evidence that the interchange instability plays a central role in the development of multiple injection channels. Plain Language Summary Magnetospheric substorms are believed to be one of the dominant processes that lead the injection of particles into the inner magnetosphere. One particular kind of substorms is called the sawtooth event, which is identified as a series of recurrent substorms. The injections during these substorms can be very wide in local time. However, in this study, we find that the wide injection boundary can break into multiple simultaneous injection channels. The results are supported by a combined investigation of numerical simulation and multipoint satellite observations. The simulation provides the time evolution of the breakup. The observations suggest that the injection channels are likely the magnetospheric source of the auroral structures. The whole process can be explained as the development of an instability, called interchange. Key Points Rice Convection Model (RCM) simulation reproduced typical features of a sawtooth substorm, including wide injection and intense dipolarization RCM simulation shows that a wide injection boundary of low‐entropy flux tubes breaks into multiple channels due to interchange instability MLT locations inferred from particle injection signatures at GEO orbit are consistent with multiple finger‐like auroral structures