Gravity wave observations in the middle atmosphere at a mid-latitude southern-hemisphere site

Abstract

The international DEEPWAVE campaign was carried out in New Zealand in 2014 to study gravity wave dynamics and vertical coupling in the lower and middle atmosphere. We present 500 hours of Rayleigh lidar measurements obtained at Lauder between June and November 2014 in the altitude range 25 to 85 km. The high temporal resolution (10 min) allows for detection of short-period gravity waves in the upper mesosphere. Gravity wave potential energy density derived from measured temperature profiles is used as proxy for gravity wave activity. It is strongly modulated by single events of one to five days duration. Gravity wave parameters like vertical wavelength and observed period are estimated using spectral analysis of wave-induced temperature perturbations and the amount of upward- and downward propagating waves is quantified. Mountain waves, detected in the lower stratosphere during strong tropospheric forcing, are generally not found to propagate to mesospheric altitudes. Short-period waves are observed in the whole altitude range, leading to large temperature perturbations in the upper mesosphere.