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Proceedings with Extended Abstracts (single PDF file) - Radio ...

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95ALWIN VHF radar: signal powerdB80Height (km)9085806040Height (km)7500:00 04:00 08:00 12:00 16:00 20:00 00:00Saura MF radar: signal power959085807500:00 04:00 08:00 12:00 16:00Time [UT] (27/07/2002)20:00 00:00dB2080604020Figure 7: Height-time plots of radar echo power observed <strong>with</strong> ALWIN VHF radar(53.5 MHz) and Saura MF radar (3.17 MHz) during the appearance of PMSE in theVHF observation. The PMSE signatures in the VHF range are overlayed to the MFradar echo power.that means soundings <strong>with</strong> a narrow and a broad beam at an off-zenith angle of 17.2 ◦ ,provides estimates of the turbulent kinetic energy dissipation rates comparable to theresults by rocket soundings (Latteck et al., 2003).Radar observations of the mesosphere can be done <strong>with</strong> different polarisations of thetransmitted signal. Interleaved transmission of the ordinary and extraordinary polarisation<strong>with</strong> a change of the polarisation from data point to data point provides differentialabsorption (DAE) and differential phase (DPE) mesasurements resulting in estimates ofthe electron number density (Fig. 6). The electron number density pro<strong>file</strong>s derived <strong>with</strong>the DAE/DPE method are in remarkable good agreement.Narrow beam MF radar observations during the appearance of polar mesospheresummer echoes (PMSE) detected <strong>with</strong> the ALWIN VHF radar show clear signatures ofexcessive signal power at PMSE altitudes during these events (Fig. 7).Summary and outlookThe Saura MF radar was put into operation in July 2002 <strong>with</strong> spaced antenna observationsand reached its full performance for Doppler beam swinging operations in April2003. The new system has high flexibility in forming of Doppler beams <strong>with</strong> various beamwidths at different off-zenith angles and azimuths. Spaced antenna and Doppler beamswinging measurements provide 3D winds, estimates of horizontal momentum fluxes andof turbulent kinetic energy dissipation rates. Height pro<strong>file</strong>s of the electron number densityare obtained from differential absorption and differential phase measurements. TheSaura MF radar, ALWIN MST radar, ALOMAR MF radar, and lidars (ALOMAR RMRlidar, ALOMAR Weber sodium lidar) at the ALOMAR observatory are located <strong>with</strong>indistances by up to 16 km allowing common volume observation in the MF/VHF frequency389

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