|
|
 |
|
|
Ann. Geophys., 23, 745-751, 2005
www.ann-geophys.net/23/745/2005/
© European Geosciences Union 2005
The effects of the pre-reversal ExB drift, the EIA asymmetry, and magnetic activity on the equatorial spread F during solar maximum
C.-C. Lee1, J.-Y. Liu2, B. W. Reinisch3, W.-S. Chen2, and F.-D. Chu2,4
1General Education Center, Ching-Yun University, No. 229, Chienshin Road, Jhongli City, Taoyuan County 320, Taiwan
2Institute of Space Science, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 320, Taiwan
3Center for Atmospheric Research, University of Massachusetts Lowell, 600 Suffolk Street, Lowell, MA 01854, USA0, Taiwan
4National Standard Time and Frequency Laboratory, Telecommunication Laboratories, No. 12 Lane 551 Ming-Tsu Road Sec. 5, Yang-Mei 326, Taiwan
Abstract. We use a digisonde at Jicamarca and a chain of GPS
receivers on the west side of South America to investigate the effects of
the pre-reversal enhancement (PRE) in ExB drift,
the asymmetry (Ia) of equatorial ionization anomaly (EIA), and the
magnetic activity (Kp) on the generation of equatorial spread F (ESF). Results
show that the ESF appears frequently in summer (November, December, January,
and February) and equinoctial (March, April, September, and October) months,
but rarely in winter (May, June, July, and August) months. The seasonal
variation in the ESF is associated with those in the PRE ExB drift and Ia. The larger ExB drift
(>20m/s) and smaller |Ia| (<0.3) in summer and
equinoctial months provide a preferable condition to development the ESF.
Conversely, the smaller ExB drift and larger
|Ia| are responsible for the lower ESF occurrence in
winter months. Regarding the effects of magnetic activity, the ESF
occurrence decreases with increasing Kp in the equinoctial and winter months,
but not in the summer months. Furthermore, the larger and smaller
ExB drifts are presented under the quiet
(Kp<3) and disturbed (Kp≥3) conditions, respectively. These results
indicate that the suppression in ESF and the decrease in ExB drifts are mainly caused by the decrease in the eastward
electric field.
Full Article in PDF (2722 KB) |
|
|
