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SYSTEM
3.3 LIMITATIONS
This section describes limiting factors or conditions for proper ATMOS 41W functionality.
Limitations occur mostly from more extreme or prolonged weather conditions but also some
cases of electromagnetic interference from power transmission lines.
3.3.1 SNOW AND ICE ACCUMULATION
The ATMOS 41W is not heated, so it will not measure frozen precipitation until snow and ice
that have accumulated in the funnel melt. In locations with heavy snowfall or long periods
below freezing, it is almost certain that snow accumulation will fill the funnel and no longer
accumulate, leading to inaccurate precipitation measurements even when the precipitation
melts. Accumulation of snow, ice, or frost will also adversely affect the accuracy of the
solar radiation measurement and can compromise the wind measurements if accumulation
occurs in the anemometer acoustic pathway or on the convex base plate (
). See
the application note
How does the ATMOS 41W perform under below freezing and snowy
(meter.ly/41w-freezing-snow) for more information on ATMOS 41W performance
in high-latitude winter.
3.3.2 HEAVY RAIN AND STRONG WIND
During strong storm events, water can splash off of the convex bottom surface of the
anemometer envelope and interrupt the signal passing between the sonic transducers.
The convex shape helps minimize splashing and reduces the likelihood that the wind
measurements are interrupted. Additionally, specially treated hydrophobic porous
polyethylene membranes protect the ultrasonic transducers from direct splashing. Despite
these features, heavy rain and strong wind can still cause water to reach the membranes
and also cause temporary water buildup on the convex surface. The hydrophobic nature of
the transducer protective membranes and the quick-drying ability of the convex surface
should limit wind measurement interruptions to heavy rain events and should bring wind
measurement back online soon after extreme conditions abate.
3.3.3 ELECTROMAGNETIC INTERFERENCE
ATMOS 41W rainfall measurements can be adversely affected by high level Electromagnetic
Interference (EMI), such as that produced by high voltage power transmission lines. Be sure
to locate the ATMOS 41W far from such sources of EMI.
