Depolarization of a 50-MHz radio wave backscattered from the middle atmosphere


  • K. Wakasugi,

  • S. Kato,

  • S. Fukao


Depolarization properties from the middle atmosphere, which refer to the change in polarization of radio waves, are investigated by using the high-powered 50-MHz radar at Jicamarca (12.0°S, 76.9°W). The echoes of the pulses transmitted alternately in right and left circular polarizations are received simultaneously by two receivers of each polarization. Small depolarization is generally observed at the altitude of 70–80 km in the mesosphere and in the stratosphere, suggesting the dominance of stable atmospheric structures. On the other hand, echoes with large depolarizations dominate the altitude of 80–90 km. The depolarization of the mesospheric scattering varies with a period of more than 10 min and shows a marked negative correlation with the echo power. In the stratosphere the fluctuation time is quite different from that in the mesosphere. The stratospheric echo power varies by 10–30 dB within a period of several to several tens of seconds and shows a close negative correlation with the depolarization. However, no correlation is observed in the period of the order of 10 min.