Comparison of automatic and manual precipitation networks in the Netherlands

This report compares the automatic precipitation network (AN) in the Netherlands with the manual network (MN) in the 2001-2013 period. At 31 locations the hourly precipitation values of AN are aggregated to daily (0800-0800 UTC) values and are compared with the daily precipitation values of the most nearby MN station measured at 0800 UTC. The influence of temperature, wind speed and precipitation intensity is explored using for each AN station the daily mean values of these variables on rain hours.

The main conclusion of the study is that AN measures annually 5-8% less precipitation than MN, with an average of 6.4% for the whole 2001-2013 period. This corresponds to about 0.3 mm per wet day. Because MN has an undercatch of about 5% (combined wind and wetting error), the total undercatch of AN equals about 10-13%. This is much larger than the WMO requirement of 5% (achievable measurement error).