The PWD series is a sensor family that can be easily and economically upgraded to meet growing measurement needs.

Ritva Siikamäki, MA he Vaisala PWD-series Editor-in-Chief provides road authorities, Vaisala Helsinki aviation authorities and Finland T meteorological organizations with the features they require: a visibility measurement range (MOR), characterization of re- duced visibility, precipitation type identification, precipitation New product family of accumulation/intensity measure- ment, and report formats (WMO, NWS code tables). The Present Weather Detectors Vaisala Visibility Sensors PWD10 and PWD20 are new models, complementing the PWD-series and Visibility Sensors offering that also comprises the Present Weather Detectors Vaisala has launched two new visibility sensors, the PWD10 and PWD12 and PWD22. Please see table 1 for details on the models PWD20, to complement the Vaisala PWD-series of Present Weather and their applications. and Visibility Sensors. The versatile PWD Series is designed to meet the visibility and present weather measurement needs of road au- Proven measurement technology thorities, aviation authorities and meteorological organizations. Of- The Vaisala Present Weather De- fering proven technology and flexible upgrade possibilities, new tectors PWD12 and PWD22 measurement capabilities can be added to the PWD sensors to meet identify precipitation type by as- growing measurement needs. sessing the water content of the

32 164/2004 precipitation with a capacitive Providing a measurement range device - the Vaisala RAINCAP® of 10 – 2,000 meters (32 – 6500 sensor element. This informa- ft), the PWD10 is, for example, tion is then combined with opti- recommended for road weather cal forward scatter and tempera- systems which alert drivers to re- ture measurements. These three duced visibility. independent measurements are For advanced road weather processed through sophisticated applications, the Vaisala Present algorithms to produce an accu- Weather Detector PWD12 pro- rate evaluation of the weather vides accurate visibility and pres- type according to the WMO ent weather measurement in the and NWS code tables. road environment. Besides Vaisala Present Weather Detector PWD22. measuring visibility the PWD12 Calibrated accuracy and also indicates the cause of re- innovative design duced visibility, by identifying automatic weather stations, espe- tems (AWOSs) and the new Vaisala PWD-series sensors are precipitation type and intensity. cially low-power AWSs, that are models have lower power con- all calibrated with reference to a In other words, the PWD pro- used for general meteorological sumption than the former ones. highly accurate transmissometer, vides a more complete picture of and aviation applications. Its ca- Additionally, detection sensitivi- and employ the proven forward- the weather conditions, which is pability of detecting freezing pre- ty in light precipitation has been scatter measurement principle to valuable information for road cipitation and reporting present improved in the PWD22, which measure Meteorological Optical authorities in the short-range weather in WMO METAR code is equipped with two RAIN- Range (MOR). The visibility planning of road maintenance format makes it a valuable addi- CAP® sensor elements. It is now sensor’s design offers protection operations. tion to AWOS systems. easier to integrate PWD series against contamination: the opti- products with simple data col- cal components point down- Long-range visibility Tactical applications lection systems, since the new wards, and the hoods protect the measurement The special Vaisala Present PWD10 and PWD20 visibility lenses against precipitation, The Vaisala Visibility Sensor Weather Sensor PWD11A used sensors also incorporate new spray and dust. The weather- PWD20 offers a longer measure- in TACMET stations will be re- analog outputs beside the stan- proof design of the PWD sen- ment range than the PWD10, placed with the new PWD22M dard serial line interfaces. sors translates into accurate extending it to 10 – 20,000 me- model, painted green. The soft- Road weather systems will measurement results in all con- ters (32 – 65,600 ft). The long- ware and mechanical interfaces be equipped with the PWD12 ditions, while reducing the need range visibility measurement is of the PWD22M are entirely instead of the former PWD11 for maintenance to a minimum. useful in diverse applications, compatible with the PWD11A model. The new present weather Optional hood heaters are re- covering harbors, coastal areas, and it fits the PWD11A slot in detector model PWD22 will re- commended for wintry condi- heliports and windmill parks the TACMET Carry Case. The place the current PWD21 model tions to prevent ice and snow ac- where visibility measurement is PWD22M will gradually replace in other applications. The soft- cumulation. necessary. The PWD22 sensor the PWD11A. ware and mechanical interfaces also incorporates long-range vi- of the PWD12 and PWD22 are Easy installation and sibility measurement capability. PWD12, PWD22 vs. compatible with the older expandability PWD11, PWD21 PWD11 and PWD21 models. All PWD sensors are compact Meteorological In comparison with the former With the new PWD-series, and light-weight. They come with applications models, PWD11 and PWD21, Vaisala reinforces its position as a cable and connector for easy in- The Vaisala Present Weather De- the new PWD12 and PWD22 the world’s leading provider of stallation, and can be mounted in tector PWD22 is a combined for- offer considerably more installa- optical sensors. The existing line many ways on any existing mast. ward scatter visibility and present tion flexibility and can be fitted of Vaisala visibility and present The measurement capabilities of weather sensor that provides a vi- with optional heaters in wintry weather sensors – the FS11, the Vaisala PWD-series sensors sibility measurement range of 10 conditions. A luminance sensor FD12P, FD12 and MITRAS can be easily and economically – 20,000 meters (32 – 65,600 ft). option is available for use in Au- Transmissometer – will continue upgraded to meet measurement The PWD22 is recommended for tomated Weather Observing Sys- to be manufactured. G needs that grow over time. Table 1. PWD Series products and their main applications Road weather Product type Main applications, main features applications Visibility sensor PWD10 Road weather systems, accurate visibility measurement up to 2 km The Vaisala Visibility Sensor PWD20 Meteorological and aviation weather, offers long-range visibility PWD10 offers economical and measurement up to 20 km reliable visibility measurement Present weather PWD12 Demanding road weather applications, short-term planning of for road weather applications. In detector maintenance operations, combined visibility and precipitation type sensor the road environment low visibi- PWD22 General meteorological applications, Automatic Weather Stations, lity is a serious safety hazard and capacity to detect freezing conditions supports warnings for significantly reduses traffic flow. safety hazards, combined visibility and precipitation type sensor

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