Quality control of precipitation data at GeoSphere Austria

Rain gauge measurement network of the Austrian national weather service is operated by GeoSphere Austria and comprises about 270 weather stations, most of which are equipped with weighing rain gauges and a smaller number with tipping bucket rain gauges. Each gauge is additionally equipped with a precipitation monitor that detects the beginning and the end of precipitation events. Precipitation data are checked for plausibility and completeness in several steps within a framework of an automated quality control tool called AQUAS (short for Austria Quality Service). The software was developed in 2016 at ZAMG (now GeoSphere Austria) in Vienna as part of the quality management in the area of real-time processing of near-surface observation data.
The basis for quality control procedure is formed by standard methods for checking meteorological and climatological data in accordance with the WMO recommendation (e.g. plausibility check, temporal, spatial and internal consistency check, etc.); in addition, test procedures are developed that take into account the specific errors of the measuring devices.  In AQUAS, individual system components are designed to test the incoming observation parameters in real time – in the case of precipitation data with a time resolution of 1 minute - as well as on the basis of daily data.
Based on the quality control of precipitation data, the structure of AQUAS and an example of its operational use are presented. An algorithm for checking precipitation data from 1-minute weighing gauge measurements is demonstrated that detects spurious precipitation events and missing gauge precipitation based on combination of the precipitation monitor observations and the total weight changes of the rain gauge. The advantage of this method is that the software errors of the weighing gauge are largely intercepted by comparison with an independent measurement. This algorithm currently supports the experts in manual quality control of precipitation data. After thorough improvements and tests, it is planned to integrate it into a semi-automatic quality control system.