In collaboration with the CRA-W (Centre wallon de Recherches agronomiques), 2 weather stations were installed at the synoptic measuring station of the R.M.I. at Humain (Marche-en-Famenne), WMO number 06472, in order to be able to compare the values measured by our stations with the official measurements of the R.M.I.
By comparing their data, we get a better understanding of how much the measured values deviate (or not) from the official ones and that in certain weather conditions.
To measure air temperature at 1.5m altitude, both BMCB weather stations use the Barani Meteoshield in which the measurement sensor is placed.
One station has a sensor for the measurement of temperature and relative humidity built into a stainless steel housing (further referred to as 'temp/hum measuring probe), the second sensor is for the measurement of temperature only and is a precision type NTC (temperature dependent resistor) which is also in a stainless steel housing.
The mass of the first probe (temp/hum measuring probe) is noticeably larger than the second probe which means that the first probe will respond more slowly to changes in ambient temperature. The time constant (that is the time required to reach ~63% of a temperature jump) of the first probe is about 90 seconds at an air speed of 1 m/s, where the time constant of the second sensor is only 20 seconds at the same air speed.
Measurements are taken every 8 seconds and the measured values are then averaged out over about another minute. Due to the larger mass of the first probe combined with even further electronic averaging, the time constant of the first probe is about 2 minutes. Of course, the shelter (in our case the Barani Meteoshield) also has its contribution in the inertia, which finaly makes everything quite complex.
In addition, there is also a Barani Meteohelix weather station present at the measurement site whose readings we would like to include in our comparison.
The file is supplemented and uploaded from time to time. It is therefore quite possible that some days' data are still missing.
