Campbell Scientific PWS100 Present Weather Sensor - Manual (Page 69)

Section 7. Operation
FIGURE 7-26. Snow water content adjustment
The mixed precipitation threshold value can be adjusted by choosing options 5-
8 on the WEATHER PARAMETERS menu. This will bring up a line asking
for a value between 0 to 1. A value of 0 means there is no threshold for mixed
precipitation – a single other type of particle in a specific event will give rise to
a mixed event, therefore mixed events are highly likely; and may easily be
caused by the occasional erroneous particle classification. A value of 1 means
an equal number of two types will have to be observed to trigger a mixed
event, therefore mixed events are highly unlikely. A setting of 0.5 means that a
second precipitation type needs to be 50% or more of the most common type to
be distinguished as a mixed event.
Four thresholds are given to allow maximum flexibility and to allow the sensor
to be setup to match local observer practise (which varies).
Option 5 controls the threshold for mixed events between two types of liquid
precipitation (e.g., rain and drizzle).
Option 6 controls the threshold for mixed events when a liquid type is the
dominant particle type and a solid is the next most prevalent particle type (e.g.,
when it is raining and snow flakes are detected). Observers are typically more
sensitive to reporting this as a mixed event than for rain/drizzle as occasional
snow flakes are easy to see.
Option 7 controls the threshold for mixed events when a solid type is the
dominant particle type and a liquid is the next most prevalent particle type
(e.g., when it is snowing but changing to rain).
Option 5 controls the threshold for mixed events between two types of solid
precipitation (e.g., snow and snow pellets).
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