Arctic and Antarctic polar mesosphere summer echoes observed with oblique incidence HF radars: analysis using simultaneous MF and VHF radar data

• Main Authors: T. Ogawa, S. Nozawa, M. Tsutsumi, N. F. Arnold, N. Nishitani, N. Sato, A. S. Yukimatu
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2004
• Subjects: Uncategorized; Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides); Arctic; Antarctic; Syowa Station; Antarc*; Antarctica
• Online Access: https://figshare.com/articles/journal_contribution/Arctic_and_Antarctic_polar_mesosphere_summer_echoes_observed_with_oblique_incidence_HF_radars_analysis_using_simultaneous_MF_and_VHF_radar_data/10158407

Polar mesosphere summer echoes (PMSEs) have been well studied using vertical incidence VHF radars at northern high-latitudes. In this paper, two PMSE events detected with the oblique incidence SuperDARN HF radars at Hankasalmi, Finland (62.3° N) and Syowa Station, Antarctica (69.0° S), are analyzed, together with simultaneous VHF and medium-frequency (MF) radar data. Altitude resolutions of the HF radars in the mesosphere and the lower thermosphere are too poor to know exact PMSE altitudes. However, a comparison of Doppler velocity from the HF radar and neutral wind velocity from the MF radar shows that PMSEs at the HF band appeared at altitudes within 80-90km, which are consistent with those from previous vertical incidence HF-VHF radar results. The HF-VHF PMSE occurrences exhibit a semidiurnal behavior, as observed by other researchers. It is found that in one event, PMSEs occurred when westward semidiurnal winds with large amplitude at 85-88km altitudes attained a maximum. When the HF-VHF PMSEs were observed at distances beyond 180km from MF radar sites, the MF radars detected no appreciable signatures of echo enhancement.