Determining True North and sensor orientation

Orientation of the wind direction sensor is done after programming the data logger, and determining the location of True North. True North is usually found by reading a magnetic compass and applying the correction for magnetic declination; where magnetic declination is the number of degrees between True North and Magnetic North. The preferred method to obtain the magnetic declination for a specific site is to use a computer service offered by NOAA at www.ngdc.noaa.gov/geomag . The magnetic declination can also be obtained from a map or local airport. A general map showing magnetic declination for the contiguous United States is shown in Magnetic declination for the conterminous United States (2015).

Declination angles east of True North are considered negative, and are subtracted from 360 degrees to get True North as shown Declination angles east of True North are subtracted from 360 to get True North (0° and 360° are the same point on a compass). For example, the declination for Logan, Utah is 11.78° East (11 August 2015). True North is 360° – 11.78°, or 348.22° as read on a compass. Declination angles west of True North are considered positive, and are added to 0 degrees to get True North as shown in Declination angles west of True North are added to 0 to get True North.

Orientation:

1. Establish a reference point on the horizon for True North.

2. Sighting down one pair of the ClimaVue 50 north south posts, aim the pair at True North. If the wind is blowing and a flag or banner can be used to determine the true wind direction, the data logger displayed wind direction reading can be compared to the true wind direction.