Stratospheric temperature anomalies and mountain waves: A three-dimensional simulation using a multi-scale weather prediction model

Abstract

A non-hydrostatic weather prediction model with an interactive grid nesting facility (MM5) is used to infer the three-dimensional mesoscale temperature field over the Scandinavian mountains during 23 January 1991. Six hours after the initialization from operational analyses warm and cold anomalies of mesoscale extent developed on isentropic surfaces at stratospheric heights over the windward slope of the mountains and further downstream. Mean mesoscale temperature fluctuations along isentropes amount to more than 4 K while minima and maxima can differ by more than 30 K, consistent with height variations exceeding 3 km. Taking into account the three-dimensional motion field cooling rates up to 20 K/h are estimated.