Simultaneous measurements of meteor winds and sporadic sodium layers in the 80 – 110 km region Original Research Article

We have made simultaneous 24-hour measurements of meteor winds and atmospheric sodium in the 80 – 110 km height range. The winds were measured by a meteor radar installed at Cachoeira Paulista (23° S, 45° W), and the sodium density was measured by lidar at São José dos Campos (23° S, 46° W). The distance between the two sites is 102 km. During the southern winter of 1999 a total of 320 hours of simultaneous measurements were obtained. Within this measurement period a large number of sporadic sodium (Ns) layers were observed. As we have previously reported, on many occasions Ns layers occur near the peaks of descending structures in the sodium layer. The simultaneous measurements reported here enable us to show that the descending structures involved are closely related to similar structures in the meridional wind profile. A clear tidal structure is visible in the sodium layer, with a vertical wavelength which corresponds to that seen in the meteor winds.