Variability of the Brunt–Väisälä frequency at the OH* layer height

Abstract

In and near the Alpine region, the most dense subnetwork of identical NDMC (Network for the Detection of Mesospheric Change, https://www.wdc.dlr.de/ndmc/) instruments can be found: five stations are equipped with OH* spectrometers which deliver a time series of mesopause temperature for each cloudless or only partially cloudy night. These measurements are suitable for the derivation of the density of gravity wave potential energy, provided that the Brunt–Väisälä frequency is known. However, OH* spectrometers do not deliver vertically resolved temperature information, which is necessary for the calculation of the Brunt–Väisälä frequency. Co-located measurements or climatological values are needed. We use 14 years of satellite-based temperature data (TIMED-SABER, 2002–2015) to investigate the inter- and intra-annual variability of the Brunt–Väisälä frequency at the OH* layer height between 43.93–48.09° N and 5.71–12.95° E and provide a climatology.