Geomagnetic control of polar mesosphere summer echoes

• Main Authors: Bremer, J., Hoffmann, P., Hansen, T. L.
• Other Authors: Leibniz-Institut für Atmosphärenphysik (IAP), Universität Rostock-Leibniz Association, The Auroral Observatory, University of Tromsø (UiT)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2000
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Alomar; Ivalo; Tromsø; Andenes
• Online Access: https://hal.science/hal-00316570; https://hal.science/hal-00316570/document; https://hal.science/hal-00316570/file/angeo-18-202-2000.pdf

International audience 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 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 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 significant influence on the PMSE during the observation period. Keywords: Ionosphere (auroral ionosphere) - Magnetospheric physics (energetic particles, precipitating) - Radio science (remote sensing)