1. Crowdsourcing Urban Wind
Arjan Droste, Daniel Fenner*, Bert Heusinkveld & Gert-Jan Steeneveld
Meteorology & Air Quality, Wageningen University *Chair of Climatology, Technische Universität Berlin

2. Mea$uring the city..?

3. Making use of Personal Weather Stations

4. The Question
Can we use crowdsourced wind observations for urban research?
Focus on the Netatmo wind module
All the same brand, easy to compare
Very popular, cheap PWS... But how good is it?

5. Data 2.5 years of Amsterdam NetAtmo data (60 stations) 23 WUR stations
Hourly averaged wind speed
Test NetAtmo at WUR weather field & TU Berlin against sonic observations

6. The NetAtmo station – Wind Gauge
Relatively new (2015); not yet validated against observations
We installed one () at our weather field to compare to our own measurements

7. Quality Control Remove 1.0 km/h hourly averages
Filter out rain & humidity
Correct for systematic underestimation

8. Wind statistics One-to-one comparison difficult due to hyperlocality
Wind (ideally) follows Weibull distribution  compare distribution fit
𝑓 𝑥 = 𝑎 𝑏 𝑥 𝑏 𝑎−1 𝑒 − ( 𝑥 𝑏 ) 𝑎 for x ≥ 0
Suboptimal for heterogeneous terrain  mixture Weibull: 2 Weibulls in 1
Weibull example
Shape says something about median wind speed: high shape = higher median WS.

9. Time to go to the city! All data between January 2017 and July 2018
Only the inner urban stations, for fair comparison
17 AAMS; 17 Netatmo stations
Step-by-step improvement through the Quality Control

11. The Good, the Bad... Wind in open field can be measured
Quality Control reduces bias
Netatmo wind distributions match reference after QC
... But contains noise & bias, suffers from moisture
... But error at low wind speeds remains
... But low wind events are still poorly captured

12. ...and the Ugly!?
All this water came out of the Netatmo sensor after being out in the field for a few months...
Thanks for your attention!

13. Low-wind event
Filtered data (left) ; filtered & bias-corrected data (right)
AAMS
Netatmo
AAMS
Netatmo
Bonus slide

14. The NetAtmo station – Wind Gauge
Specifications
Height: 110 mm / Diameter: 85 mm
4 ultrasonic transducers measure wind
Wind speed: Range: 0 to 45 m/s; Accuracy: 0.5 m/s
Wind direction: Accuracy: 5°
Records wind speed, direction & gusts
Bonus slide