Vaisala WAA151 Installation Manual download pdf (Page 69)

Chapter 3 __________________________________________________________ Selecting Location

VAISALA ________________________________________________________________________ 67

In areas of homogeneous dense vegetation, the height of the

vegetation should be kept below the gauge orifice level by regular

clipping. Sites on a slope or on the roof of a building should be

avoided. Also hard flat surfaces such as concrete should be avoided to

prevent excessive in splashing.

Solar Radiation

Make sure that no building or object will shadow the station,

especially the solar panel and solar radiation sensors, during the day.

On the Northern Hemisphere, the solar radiation sensors should be

installed on the southern side of the MAWS (on the Southern

Hemisphere, vice versa) to avoid other weather station structures

shading the sensor. To facilitate leveling/cleaning, installing at a

height of 3 m or less is recommended.

The solar panel should face south (true south, not magnetic) on the

Northern Hemisphere and north on the Southern Hemisphere.

Soil Temperature

Finding a suitable site for QMT103 or QMT107 Soil Temperature

Probe is important for getting representative soil temperature

measurements. Measurement site should be 1 m² and typical of the

surface of interest. The ground surface should be level with respect to

the immediate (10 m radius) area.

The QMT107 probes are pressed into pre-formed holes, but they can

also be placed into excavated holes that are then filled. On hard or

rocky ground, a pilot hole is pre-formed with an auger rod.

Soil Moisture

The soil water content measured by the ML2x sensor within one small

locality can be affected by:

- Variations in soil density and composition

- Stones close to the rods

- Roots (either nearby or pierced by the rods)

- Earth worm holes or mole holes

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Vaisala WAA151 Installation Manual Page 69