Vaisala WMT700 - Manual (Page 60)

User's Guide ______________________________________________________________________
Selecting Installation Location
Finding a suitable site for WMT700 is important for getting
representative ambient measurements. Select a site that represents
the general area of interest. Follow the WMO Guide to
Meteorological Instruments and Methods of Observation WMO-
No. 8, or other application-specific requirements set by various
organizations, like the International Civil Aviation Organization
(ICAO).
It is important to take into account the geography and surrounding
area to achieve optimum performance. Trees, buildings, or other
objects situated in the vicinity of WMT700 disturb free air flow
and thus affect the accuracy of the measurement results.
Ideally, WMT700 should be higher than any other object within a
horizontal radius of 300 m. In general, any object of height (h)
does not remarkably disturb wind measurement at a minimum
distance of 10 x h.
When mounting WMT700 on top of a building, the recommended
minimum height (h) for the mast is 1.5 × the height of the
building (H). When the diagonal (W) is less than the height (H),
the minimum height of the mast is 1.5 × W.
When there is a need to ensure free air flow with a cross arm
installation, the distance (y) between WMT700 and the mast
should be more than 20 × the diameter of the vertical mast (z).
For more information, see Figure 19 on page 59 and follow
application-specific installation guidelines.
When mounting two WMT700 wind sensors at the same height,
make sure that there is a minimum of 10 meters of distance
between the two devices, as shown in Figure 21 on page 61. If the
difference in the height of the sensors is at least 0.5 meters, it is
enough to have a minimum distance of 2 meters between the two
devices to avoid possible acoustical interference between them.
WARNING If ice or snow accumulates on WMT700 or the mast, it can fall and cause
injury to persons below.
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