A new concept for high resolution temperature analysis over complex terrain

The analysis of high resolution temperature data over complex topography is often problematic due to the specific influence of orography and thus, requires a special methodology. The new concept of Low Level Temperature (LLT) is defined, and can be obtained when potential temperature observations are reduced to the height of the so-called Minimum Topography, a special low level topography that accentuates basins and valleys but smoothes out single summits and scarped slopes. The Vienna Enhanced Resolution Analysis (VERA) is used to produce a comprehensive set of LLT analyses over the Alpine region by evaluating three-hourly synoptic ECMWF data for the period 1980-2001. LLT fields are then evaluated climatologically in order to gain two-dimensional representations and single grid point time series. Mean LLT fields for different months and times of the day provide highly resolved spatial and temporal information on temperature fields over basins and valleys i.e., the main settlement areas in mountainous terrain.