Some evidence of ground power enhancements at frequencies of global magnetospheric modes at low latitude |
| |
Authors: | P Francia U Villante |
| |
Institution: | (1) Dipartimento di Fisica, Universita dell Aquila, I-L Aquila, Italy |
| |
Abstract: | A statistical analysis of the power spectra of the geomagnetic field components H and D for periods ranging between 3 min and 1 h was conducted at a lowlatitude observatory ( Aquila, L = 1.6) at the minimum and maximum of the solar cycle. For both components, during daytime intervals, we found evidence of power enhancements at frequencies predicted for global modes of the Earth s magnetosphere and occasionally observed at auroral latitudes in the F-region drift velocities (approximately at 1.3, 1.9, 2.6, and 3.4 mHz). Nighttime observations reveal a relative low frequency H enhancement associated with the bay occurrence together with a peak in the H/D power ratio which sharply emerges at 1.2 mHz in the premidnight sector. The strong similarity between solar minimum and maximum suggests that these modes can be considered permanent magnetospheric features. A separate analysis on a two-month interval shows that the observed spectral characteristics are amplified by conditions of high-velocity solar wind. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|