First continuous ground-based observations of long period oscillations in the vertically resolved wind field of the stratosphere and mesosphere

Abstract

Direct measurements of middle-atmospheric wind oscillations with periods between 5 and 50 days in the altitude range between mid-stratosphere (5hPa) and upper mesosphere (0.02hPa) have been made using a novel ground-based Doppler wind radiometer. The oscillations were not inferred from tracer measurements, as the radiometer offers the unique capability of near-continuous horizontal wind profile measurements. Observations from four campaigns at high, middle and low latitudes with an average duration of 10 months have been analyzed. The dominant oscillation has mostly been found to lie in the extra-long period range (20-50 days), while the well-known atmospheric normal modes around 5, 10 and 16 days have also been observed. Comparisons of our results with ECMWF operational analysis data revealed remarkably good agreement below 0.3hPa but discrepancies above.