Comparison of automatic and manual precipitation networks in the Netherlands

KNMI operates two networks for in-situ precipitation measurements in the Netherlands. The first is an automatic network (AN) of 32 stations, where precipitation is measured continuously with automatic rain gauges. This network almost coincides with the network of automatic weather stations (AWS). The second is a dense manual network (MN) of about 325 stations, where voluntary observers measure 24-hour precipitation sums once per day at 0800 UTC. The AN has a high temporal resolution (currently 1-min). This is important for the study of shortduration extremes, nowcasting and, increasingly, for real-time radar calibration. The MN has a long continuity of instruments and methods and is important for climate monitoring and hydrological research and applications.

Today there is a growing need to expand AN, mainly to improve real time radar calibration for hydrological purposes. On the other hand, there is a need to continue MN for climate monitoring purposes. To obtain an optimal combination of AN and MN it is important to compare both networks and to understand differences in precipitation measurements obtained with both networks. This report describes this comparison and may serve as background information for the design of the precipitation networks in the Netherlands and elsewhere.