Temporal Evolution and Structure of Surface Inversions over Complex Terrain

This study focuses on the establishment of a robust relation between night time surface inversion formation and topographic features like slope angles, concavity or convexity and elevation variations, land type, etc. at different scales. First the temperature from the daily soundings from Vienna and Innsbruck were compared with the temperature data from the model levels of the ERA Interim for two years. Then a statistic was made to see the difference between the temperature from the model and the observations. Furthermore observed surface temperatures and additionally temperature data from ERA Interim at several pressure levels have been used to obtain a statistic of inversion strength at each surface station location in Austria. The correlation between inversion strength and the topographic and land type characteristics is used, to estimate the inversion strength on a fine grid along the topography in the whole Alpine region for each season. This high resolution patterns are used as "fingerprints" for the downscaling procedure of surface temperature fields with the VERA (Vienna Enhanced Resolution Analysis) scheme. Some results and improvements of the methodology will be shown and discussed.