Surface Observations

Continuity and quality of the meteorological surface observations are of crucial importance to end users in weather, climate and aeronautical application areas.

Significant effort is undertaken at KNMI to understand and improve the meteorological measurements from sensor to end product, including their calibration, underlying algorithms, validation and traceability to international standards.

The RDWD activities concerning surface observations involve:

  • Specification, selection, evaluation and implementation of sensor replacements for operational sensors that are at the end of their life cycle.
  • Evaluation of new measurement techniques with economical or quality advantages.
  • Investigation of sensor behaviour and data processing in order to solve known shortcomings.
  • Exploration of new sensors or data products that are a potential source of additional information.
  • Advise on sensor and data products.

Sensor Research
KNMI aims to continually improve its observation infrastructure in order to keep it up-to-date and cost-effective. This is generally reached by the transition from one to another instrument, but introductions of new sensors or new data products also occur. The implementation of a new sensor requires extensive laboratory and field tests to assess its measuring characteristics and performance under a wide variety of weather conditions. This delivers fit-for-purpose information for end users enabling correct interpretation of the data, and understanding differences between succeeding measurement techniques. Close collaboration in these tests with end users from different disciplines is important, in order to ensure that the new technique meets their requirements.



Acceptance test of the Lufft CHM15k ceilometer at the Cabauw research site.
Acceptance test of the Lufft CHM15k ceilometer at the Cabauw research site.
Present Weather Sensors under evaluation at the test field in De Bilt.
Present Weather Sensors under evaluation at the test field in De Bilt.

Automated Observing Methods
The national meteorological observing network in the Netherlands has been fully automated during the last two decades. This concerns all observation products for weather, climate and aeronautical applications, except for the aeronautical observations of Schiphol airport. Various in-situ and remote sensing techniques are deployed to deliver not only measurements of temperature, atmospheric pressure, humidity, wind, precipitation and radiation, but also visibility, present weather and clouds. In order to optimize the benefits for the user, the processing software in the chain between sensor and data product is continually being improved. Nowadays, there is a tendency towards “smarter” and more synergetic use of the measurements, for example to increase their spatial representativeness and hence their level of meeting user requirements. Furthermore, a strong increase in combining traditional in-situ observations with satellite data or low cost measurements into new products is envisaged.


(Inter)national forums and facilities
RDWD participates in international forums of WMO-CIMO, EUMETNET, ICAO, MET Alliance to exchange experiences on sensor research and the  automation of observations. It also employs a test field in De Bilt that contains amongst others a visibility standard and that in the near future will be equipped with a standard WMO setup for precipitation amount and intensity measurements. The test facilities are also used by universities and manufacturers.