Humidity sensors for land and maritime stations

In order to find a suitable humidity sensor for the KNMI measuring network, a set of five different sensor types from three different manufacturers has been subjected to a number of tests.
Laboratory tests have been performed to test the accuracy of the sensors. The time response of the sensors has also been measured accurately in the laboratory under various conditions.
Results of the tests on sensor accuracy show a temperature dependence at low temperatures and high humidity for some sensors. Response times vary significantly, but are all within WMO recommendations.
Based on these test results, 2 sensor types have been selected for field tests. These field tests take place at a land station (De Bilt) and on a North Sea platform and last up to a year in duration. These tests give an indication of condensation effects, contamination rates, contamination effects and therefore possible future calibration intervals.
The final results of the laboratory tests is shown, as well as the progress of the field tests.