Seasonal and solar cycle variations of the auroral electrojet indices

Details Seasonal and solar cycle variations of the auroral electrojet indices Seasonal and solar cycle variations of the auroral electrojet indices

Sep 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000jastp..62.1301a&link_type=abstract

Journal of Atmospheric and Solar-Terrestrial Physics, Volume 62, Issue 14, p. 1301-1310.

Physics

11

Scientific paper

Using hourly mean auroral electrojet indices for the past 20 years, we examine the seasonal and solar cycle variations of the AU and AL indices as well as the smaller time-scale fluctuations in these indices. The AU and AL indices maximize during summer and equinoctial months, respectively. By removing the effects of the solar conductance from the AU index, it is found that the electric field contribution to the AU index exhibits the same semiannual variation pattern as the AL index, indicating that the semiannual magnetic variations are controlled by the electric field. Since the auroral electrojets are mostly Hall currents flowing in the east-west direction, the fluctuations of the auroral electrojet indices can be interpreted in terms of fluctuations in the north-south component of the electric field and the Hall conductance. The AU fluctuation is largely due to that of the electric field, while the AL fluctuation is attributed to both the electric field and Hall conductance with their contributions being comparable. The high fluctuation of AL compared to that of AU is attributed to particle precipitation associated with substorm activity. However, the fluctuations of the electric field and conductance do not show any noticeable seasonal dependence. The variation pattern of the yearly mean AL index follows the mirror image of the AU index during the past 20 years, indicating that the absolute values of the two indices are proportional to each other. This suggests again that the electric field is the main modulator of magnetic disturbance. On the other hand, they show a tendency to become higher during the declining phase of the solar cycle. This is the same variation pattern confirmed from the aa index. However, the fluctuations of the electric field and the Hall conductance do not show any apparent dependence on the solar cycle.

Affiliated with

Also associated with

No associations

Rating

Seasonal and solar cycle variations of the auroral electrojet indices 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 Seasonal and solar cycle variations of the auroral electrojet indices, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seasonal and solar cycle variations of the auroral electrojet indices will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1386631