Geomagnetic control of polar mesosphere summer echoes

• Main Authors: J. Bremer, T. L. Hansen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2000
• Subjects: Alomar; Ivalo; Tromsø; Andenes
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.580.6001; http://www.ann-geophys.net/18/202/2000/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 Observa-tory Tromsø (69.66°N, 18.94°E). During night-time and morning hours a significant correlation between the signal-to-noise ratio (SNR) of the radar results and the geomagnetic K indices could be detected with a maxi-mum correlation near midnight. The correlation be-comes 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 varia-tion, however, has no significant influence on the PMSE during the observation period.