Vaisala WINDCAP WS425 Guide de l'utilisateur télécharger pdf (Page 27)

Chapter 3 _______________________________________________________________ Installation

VAISALA _______________________________________________________________________ 27

Alignment

Magnetic Declination Correction

One transducer arm is permanently marked with an N for north and

another with an S for south.

NOTE

Aligning might be easier if you mark the sensor body, for example, with

paint or colored tape, to indicate north and south so that it can be seen

from the ground.

Wind direction can be referenced to either the true north, which uses the

earth’s geographic meridians, or to the magnetic north, which is read

with a magnetic compass. The magnetic declination is the difference in

degrees between the true north and magnetic north. See Figure 4 below.

0003-011

Figure 4 Sketch of Magnetic Declination

NOTE

The source for the magnetic declination must be current as the

declination changes over time.

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Vaisala WINDCAP WS425 Guide de l'utilisateur Page 27