Wind Measurement in RWS10

The RWS10 measures wind speed only. The method is an indirect data analysis with patent-pending technology. No attempt is made to estimate the direction of the wind because even accurate data measured from a typical road weather station does not represent a larger area. The most important use for wind measurement is probably the assessment of the creepiness of snow and warnings of dangerous winds, for example on large bridges and in the mountains.

Typically, the wind measurement of a road weather station reports lower speeds than a meteorically positioned measurement. In Finnish conditions, when there are a lot of forests, many Meteorological Institute stations tend to give unnecessarily low speeds because they measure it in too sheltered places. Nuuksio’s position in this comparison is already a borderline case.

The Nuuksio weather station (60.29128, 24.56782) is an official metering point of the Finnish Meteorological Institute (FMI) and it is closest to the Ollila and Espoo test stations. The distance is about 7 km south of the Ollila road weather stations and 5 km southwest of RWS10 in Espoo (S03). In Arkala (S005), the nearest representative measurement point is at Pudasjärvi Airport, approximately 50 km away. Oulu is a little closer, but it is more in a marine environment.

Fig. 1. Location of Ollila, Espoo and Nuuksio weather stations.

An example in Fig. 2 shows wind 10-minute average and gust speeds with a variable wind direction on 2022-01-04. In Fig. 3 there is an example of wind speed and gust speed during a northwest and west wind on 2022-01-06. Because the FMI’s data is easily obtained in UTC time, the first 2 hours are omitted here when the time stamps are aligned to the same time in UTC + 2.

Fig. 2. Ten-minute average wind speed (upper) and gust speed (lower) from RWS10 (blue), Ollila station (red) and FMI Nuuksio station (green) on 2022-01-04.

Fig. 3. Ten-minute average wind speed (upper) and gust speed (lower) from RWS10 (blue), Ollila station (red) and Nuuksio station (green) on 2022-01-06.

Fig. 4. Ten-minute average wind speed (upper) and gust speed (lower) from RWS10 in Arkala (blue), ROSA station in Arkala (red), Pudasjärvi airport station (green), and Oulu airport (violet) during strong easterly wind on 2022-01-06.

The speeds measured by the RWS10 station are clearly higher than those measured at the road weather station, but are more in line with those measured at the general weather station. Compared to the use of road weather stations, the measurement of wind speed in the RWS10 is sufficiently accurate and no separate sensor or mast is required. In the RWS10, the structure is also protected from freezing and from birds, which even tend to mechanically break vanes, anemometers and ultrasonic wind sensors. Since the surroundings can also affect the wind result in the RWS10, there is a scaling factor available in the device to adjust the result.

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