VERACLIM - A high resolution Reanalysis of the Alpine Atmosphere

Reanalyses of the Atmosphere based on a uniform analysis/ data assimilation scheme are needed for refined climatological studies, to derive statistical properties of the atmospheric behaviour and eventually to detect signals of the global change . The resolution of todays most sophisticated global reanalyses is still not sufficient to investigate small scale features e. g. with regard to mountains. Therefore in data dense areas like over the European Alps it makes sense to analyze atmospheric fields with higher spatial and temporal resolution than the global fields, even with less sophisticated analysis methods.

The VERA (Vienna Enhanced Resolution Analysis) has been used to generate series of 3-hourly fields of the low level atmosphere over the Alps for the last 25 years. This analysis scheme represents a thin plate spline approach including a quality control module and a downscaling module based on a 1 km topographic grid. Fields of the sea level pressure, the low level potential and equivalent potential temperature, the precipitation and wind are being evaluated to learn more about the statistical-climatological behaviour of the Alpine atmosphere. Due to the high spatial resolution (10 and 20 km respectively) small scale phenomena like topographically induced thermal circulation systems, topographically blocked or channelled flows, splitting points or meso-vortices can be detected. Selected results of the evaluation will be presented and discussed.