Changes in Actuele10mindataKNMIstations
In the Actuele10mindataKNMIstations dataset, significant changes will be implemented on 20 November 2023 that affect how we present meteorological data. These changes are intended to enhance the quality and usability of the data and ensure compliance with international standards and regulations. We remain committed to providing accurate and reliable meteorological information for everyone. Again, we have created a test file for you to use in advance.
The stations are identified by their WMO ID, which can be translated using this dataset: weather stations (CSV)
Addition of WIGOS Station Identifier
We have introduced a new ID for the stations, the WIGOS Station Identifier (WSI). This has been added alongside the old WMO identifier, which had a 5-digit format. The WMO Identifier proved to be too short for many countries to include all stations with unique numbers, leading WMO to choose a new format. Adding the WSI allows us to register our observation stations and platforms with the OSCAR/Surface database.
Removal of variables qr, qrn, and qrx for all stations
The variable qr (Raw Global Solar Radiation 10 Min Average) is calculated from the variable qg to analyse the measurement from the sensor in slightly higher resolution. The variable qr is a conversion of qg according to the following formula: QR = ceiling(4 X QG – ½) + 200, where "ceiling" means rounding up. The variable qr is intended for internal use only, where it is used to analyse sensor performance. Additionally, qr gives possibilities to inspect the sensors at night, whereas qg is always equal 0 at night. It is important to emphasize that qr does not provide additional meteorological information. For this reason, it was decided to remove qr for all stations, along with its associated minimum value, qrn, and maximum value, qrx.
Removal of ta, td, rh, tb, and tg for mist posts
For mist posts 06233, 06236, 06237, and 06238, where measurements meet specific aviation requirements, we have chosen to remove derived variables (ta, td, rh, tb, and tg) from the data product in KDP. Mist posts have sensors for temperature and humidity at different heights, making the data quality different from other AWS locations. Voorschoten (06215) is also classified as a mist post, but here the sensors are at the same height as other AWS locations.
Additionally, we have changed the unit of qnh from W m-2 to hPa. Qnh is the atmospheric pressure reduced to sea level in hPa, according to international aviation regulations. If you want to use atmospheric pressure, we recommend using the variable pp.
Other notes regarding metadata
We have made some improvements to the comments in the metadata for the Actuele10mindataKNMIstations. For instance, visibility sensors at 'AWS' locations are placed at a height of 1.80m, while at AWS/aerodrome and mist post locations (including Voorschoten), they are placed at 2.50m. This is related to the ground-level visibility and pilot's eye level. There are a few exceptions where the visibility sensor is also at 2.50m, and these are the stations 06249, 06260, and 06290.
Wind measurements are typically supposed to be taken at a height of 10m, but there are variations in sensor height and data collection methods at some locations. Details about which stations deviate can be found in the comments for various wind variables.