DOI: 10.16904/envidat.116
title: Snow Drift Station - 3D Ultrasonic

description: A Young 81000 sonic anemomenter was deployed at Gotschnagrat (LON: 46.859 LAT: 9.849) to record three components of the wind velocity (u, v, w in [m s&8254; &185;]) and air temperature (Ts in [°C]). The anemomenter was mounted in direction North at a height of 1.5 m above snow surface at the beginning. The time within each data set is given in UTC+1. Instrument specifications can be found [here](http://www.youngusa.com/Manuals/81000-90(I).pdf) .
description: Resource Title: Sonic wind component u
 Size: 513827192 bytes
 Format: .npy
 URL: https://www.envidat.ch/dataset/efa1aa57-2aef-41de-8d36-d5847445a2dc/resource/54108b5f-082b-483b-8ac0-a56780e44217/download/sonic_u.npy
 Description: The data contains values for u direction of the wind in a sampling frequency of 20 Hz. 
Erroneour spikes were filterd in two steps. 

1. Define moving window uₓ = u(i-3:i+3)
2. If u(i)-mean(uₓ) &gt; 2*std(uₓ):u(i) = NaN

Frozen detectors resulted in continuous zero values (not filtered).
The wind speed and direction were calculated as follows:

wind speed = sqrt(u² + v²) 
wind direction = 180° + (180° / PI)* arctan2 (-u, -v)
description: Resource Title: Sonic wind component v
 Size: 513827192 bytes
 Format: .npy
 URL: https://www.envidat.ch/dataset/efa1aa57-2aef-41de-8d36-d5847445a2dc/resource/a485c9f7-72e0-474c-9bc8-3d9aea695a30/download/sonic_v.npy
 Description: The data contains values for v direction of the wind in a sampling frequency of 20 Hz. 
Erroneour spikes were filterd in two steps. 

1. Define moving window uₓ = u(i-3:i+3)
2. If u(i)-mean(uₓ) &gt; 2*std(uₓ):u(i) = NaN

Frozen detectors resulted in continuous zero values (not filtered).
The wind speed and direction were calculated as follows:

wind speed = sqrt(u² + v²) 
wind direction = 180° + (180° / PI)* arctan2 (-u, -v)
description: Resource Title: Sonic wind component w
 Size: 513827192 bytes
 Format: .npy
 URL: https://www.envidat.ch/dataset/efa1aa57-2aef-41de-8d36-d5847445a2dc/resource/a0d480eb-e00a-4508-9d76-16da99c61b61/download/sonic_w.npy
 Description: The data contains values for w direction of the wind in a sampling frequency of 20 Hz. 
Erroneour spikes were filterd in two steps. 

1. Define moving window uₓ = u(i-3:i+3)
2. If u(i)-mean(uₓ) &gt; 2*std(uₓ):u(i) = NaN

Frozen detectors resulted in continuous zero values (not filtered).
The wind speed and direction were calculated as follows:

wind speed = sqrt(u² + v²) 
wind direction = 180° + (180° / PI)* arctan2 (-u, -v)
description: Resource Title: Sonic temperature
 Size: 513827192 bytes
 Format: .npy
 URL: https://www.envidat.ch/dataset/efa1aa57-2aef-41de-8d36-d5847445a2dc/resource/cc5577c8-af52-4af3-a16c-bef536dbe363/download/sonic_ts.npy
 Description: The data set contains values of temperature (°C) measured with the anemometer at a sampling frequency of 20 Hz.
description: Resource Title: Sonic time
 Size: 513827192 bytes
 Format: .npy
 URL: https://www.envidat.ch/dataset/efa1aa57-2aef-41de-8d36-d5847445a2dc/resource/d345ded1-1574-41f3-ae30-d257dc87b926/download/sonic_time.npy
 Description: The data set contains the time in YYYY-mm-dd HH:MM:SS.sss for the anemometer data. The time is given in UTC+1.