PWS100 Present Weather Sensor - Campbell Scientific
PWS100 Present Weather Sensor - Campbell Scientific
PWS100 Present Weather Sensor - Campbell Scientific
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Section 4. Overview<br />
The <strong>PWS100</strong> <strong>Present</strong> <strong>Weather</strong> <strong>Sensor</strong> is a laser based sensor capable of<br />
determining precipitation and visibility parameters for automatic weather<br />
stations including road, marine and airport stations. Due to its advanced<br />
measurement technique and fuzzy logic algorithms, the <strong>PWS100</strong> can determine<br />
each individual precipitation particle type from accurate size and velocity<br />
measurements and the structure of the received signal.<br />
The system can output visibility and precipitation related weather codes such<br />
as those detailed in the World Meteorological Organisation (WMO) SYNOP<br />
code, those used as part of a METAR weather report and those previously used<br />
by the US National <strong>Weather</strong> Service (NWS).<br />
Further details of precipitation can be given in terms of drop size distributions<br />
(DSD) and particle size / velocity maps to give better indications of<br />
precipitation intensity. Such distributions can then be used in soil erosion<br />
studies.<br />
The <strong>PWS100</strong> comprises a Digital Signal Processor (DSP) housing unit<br />
connected to a sensor arm, comprising one laser head and two sensor heads.<br />
Each of the sensor heads is 20° off axis to the laser unit axis, one in the<br />
horizontal plane, the other in the vertical plane. The DSP housing is fixed via a<br />
mounting bracket to a mast, though a tripod can be used for temporary sites.<br />
Figure 4-1 shows the <strong>PWS100</strong> mounted on a pole.<br />
An optional CS215-PWS temperature and humidity sensor is normally<br />
supplied and plugs directly into the <strong>PWS100</strong>. That sensor is used to improve<br />
the accuracy of weather coding by the PWS, in particular in respect of<br />
discriminating between snow and rain and also fog/mist and dust.<br />
FIGURE 4-1. <strong>PWS100</strong><br />
4-1