A Simple Step by Step Method for the Alignment of Wind Sensors to True North

The proper alignment of wind sensors to true north has always presented a challenge to even the most experienced user. The traditional method of applying a known declination to measurements of magnetic north can be complicated by local aberrations in the earth's magnetic field as well as magnetic interferences buried in the ground or adjacent to the measurement site. This paper presents a simple step by step method for determining the pointing direction or alignment of a sensor without having to know the local declination. The method relies on the calculated azimuth angle of the sun and its' relative angle to the meteorological sensor of interest. The method is unaffected by any local magnetic interference and can therefore be used on top of buildings or in areas with significant ferrous metals. The accuracy of the method is only limited by the device that is used to measure the different angles. In the case of the simple tripod mounted pocket transit used for the method development, the accuracy was estimated to be about one degree.