Relevance of mountain wave cooling for the formation of polar stratospheric clouds over Scandinavia: Mesoscale dynamics and observations for January 1997

The effect of mesoscale mountain wave-induced temperature anomalies on the formation potential of polar stratospheric clouds above northern Scandinavi a is analyzed with a one-month mesoscale model integration. The simulation results are contrasted with synoptic-scale analyses and compared with remot e sensing and in situ observations. The mesoscale mass flux of air parcels with temperatures below the threshold for cloud formation through a control volume is compared with its synoptic-scale counterpart. A classification o f the synoptic-scale flow into periods of large and small mountain wave act ivity in the stratosphere is proposed. The derived classification will be u sed for a climatology of stratospheric mountain wave activity above Scandin avia.