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Chapter 5__________________________________________________________________ Operation
where
Precipitation limit
Weather update delay
Rain intensity scale
Heavy rain limit
Light rain limit
Snow limit
Heavy snow limit
Light snow limit
DRD scale
VAISALA ________________________________________________________________________ 69
=
The threshold of accumulated particle magnitudes
(in PWD22 internal units) to report the
precipitation state 'on'. A typical parameter value is
20 to 60 (max. 255). A smaller value is more
sensitive operation and faster response at the
beginning of an event. and it is also more sensitive
to false rain and snow reports.
=
A time as multiple of 15 seconds, during which the
instant precipitation type is not changed. The
intensity may change faster.
=
It is multiplied by the measured raw intensity gives
the reported precipitation intensity (optical). The
rain amount is scaled with the same coefficient
because the amount is a direct integral of 15-
second intensities.
A typical value for the Rain intensity scale is 1.0.
Since the optimal value depends on the optical,
optoelectronic, and electronic parameters in a very
complex way, no applicable factory calibration
method has been developed yet.
=
The minimum rain intensity (mm/h), when the
intensity is reported as heavy.
=
The maximum rain intensity (mm/h), when the
intensity is reported as light. If rain intensity is
between the above heavy and light limits, it is
reported as moderate.
=
The minimum ratio of optical precipitation
intensity to surface sensor (
precipitation intensity, when precipitation is snow.
A typical value for Snow limit is 5. Smaller value
directs PWD22 to report more wet precipitation as
snow.
=
The maximum visibility (m) of two-minute
average in heavy snow.
=
The minimum visibility (m) of two-minute average
in light snow. If snow is detected and the two-
minute average visibility is between the above
heavy and light limits, snow intensity is reported as
moderate.
=
The scaling factor for the calculated intensity of
®
the RAINCAP
this parameter is 1.0.
®
)
RAINCAP
surface sensor. A typical value for
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