Northring for Ultrasonic anemometer

The adapter is used for the north alignment of a Ultrasonic anemometer.
The adapter is installed between mast and sensor. The adapter is aligned to north by means of a bearing tube. After alignment the sensor is mounted onto the adapter. A pin in the adapter and a north boring in the base of the anemometer guarantee that the sensor is aligned to north. There is no re-alignment necessary with replacement of the sensor.