• Main Authors: J. Bremer, T. L. Hansen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Alomar; Ivalo; Andenes
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.371.7469; http://hal.archives-ouvertes.fr/docs/00/31/65/70/PDF/angeo-18-202-2000.pdf

Abstract. Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E) from 1994 until 1997 polar mesosphere summer echoes (PMSE) have been investigated in dependence on geomagnetic K indices derived at the Auroral Observatory Tromsù (69.66°N, 18.94°E). During night-time and morning hours a signi®cant correlation between the signal-to-noise ratio (SNR) of the radar results and the geomagnetic K indices could be detected with a maximum correlation near midnight. The correlation becomes markedly smaller in the afternoon and early evening hours with a minimum near 17 UT. This diurnal variation is in reasonable agreement with riometer absorption at Ivalo (68.55°N, 27.28°E) and can be explained by the diurnal variation of ionization due to precipitating high energetic particles. Therefore, a part of the diurnal PMSE variation is caused by this particle precipitation. The variability of the solar EUV variation, however, has no signi®cant in¯uence on the PMSE during the observation period.