Auroral particle precipitation characterized by the substorm cycle. Issue 3 (1st March 2013)

• Record Type: Journal Article
• Authors: Wing, Simon; Gkioulidou, Matina; Johnson, Jay R.; Newell, Patrick T.; Wang, Chih‐Ping
• Is Part Of: Journal of geophysical research. Volume 118:Issue 3(2013:Mar.)
• Page Start: 1022
• Page End: 1039
• Publication Date: 2013-03-01
• Subjects: particle precipitation -- substorm -- diffuse aurora -- wave aurora -- ion aurora -- monoenergetic aurora; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/jgra.50160
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract : [1] Substorms release a large amount of energy, some of which is used to energize the precipitating particles in the polar region. Superposed epoch analysis was performed with 11 years of DMSP SSJ/4/5 data to characterize the substorm cycle of the diffuse, monoenergetic, and broadband/wave precipitating electrons and precipitating ions. Although substorms only increase the ion pressure by 30%, they increase the power of the diffuse, monoenergetic, and wave electron aurora by 310%, 71%, and 170%, respectively. Substorms energize the ion aurora mainly in the 21:00–05:00 magnetic local time (MLT) sector. The dynamics of the diffuse electron aurora are different from those of the other two electron aurorae. The expansion phase duration is approximately 15 min for the monoenergetic and wave electron aurorae, whereas it is 1 h for the diffuse electron aurora. The monoenergetic and wave electron aurorae appear to complete the substorm cycle within a 5 h interval, whereas the diffuse electron aurora takes more than 5 h. The diffuse electron aurora power and energy flux start increasing at 15 min before the substorm onset, whereas those for the monoenergetic and wave electron aurorae start increasing at 1 h and 15 min before the onset. The increase in the monoenergetic electron aurora power and energy flux may result from the increase in the magnetotail stretching and region‐1 field‐aligned current during the growth phase. The monoenergetic electrons may also be associated with fast flows, which have been previously observed more frequently in the dusk‐midnight sector. Key Points: Wave aurora increases at substorm onset, but it decreases rapidly 15 min after Monoenergetic aurora starts increasing about 75 min before the substorm onset Monoenergetic and wave electron aurorae complete the substorm cycle within 5 hr