HMP155 & sensor response time effect on measurement error

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Its worth noting that the temperature time constant listed for the HMP155 is at a hefty 3 m/s airflow speed as shown in the photo from its manual. Thus the HMP155 temperature time constant converted to still air will, unfortunately, be significantly higher and hence the HMP155 temperature measurement error due to fluctuating air temperature will NOT be per WMO recommended guidelines as specified in the WMO – The CIMO Guide – Guide to Meteorological Instruments and Methods of Observation, 2014 Edition updated in 2017.

Due to the slow time response of this temperature sensor, an air temperature fluctuation of 2 °C over a period of 2 minutes in 3 m/s airflow will show a measurement error of 0.29 °C (at 3 m/s air speed) on top of the basic sensor accuracy/uncertainty.

Flow obstruction caused by a radiation shield will significantly increase this error for low wind speeds. Despite the status quo, it will be very hard to justify the HMP155’s use for precision climatic measurement. In 1 m/s air, the time constant can rise to 35 seconds and in 0.5 m/s air to 49 seconds, thus producing errors over 0.5 °C due to only the sensor’s slow response time.

Monitoring climate change in the South Pacific while helping local agriculture

BARANI MeteoHelix® weather station in the South Pacific with a RainWise rain gauge. ( Image: Nouvelle station petit by https://repair.nc)

BARANI MeteoHelix® weather station in the South Pacific with a RainWise rain gauge. ( Image: Nouvelle station petit by https://repair.nc)

As part of a pilot project on water management started in July 2018 in New Caledonia in the South Pacific, the MeteoHelix® IoT Pro weather stations connected through the wireless Sigfox network will provide critical weather information at never before possible all-weather accuracy. The quality of weather information supplied by the new MeteoHelix® weather stations is such, that it will be able to be used for climatological monitoring of global warming in addition to its primary use for water management and agriculture. The weather stations were supplied by http://www.iot.nc, a leader in IoT development in the South Pacific.

If you wish to contribute and give your ideas for the development of this application, please contact the REPAIR team below:

https://repair.nc/actualites/
tel: +687 27 21 88
contact@repair.nc

Repair.nc
Complexe commerciale La Belle Vie
6ème km
Bâtiment BCI, 2ème étage
98800 Nouméa BP 27098

MeteoHelix® IoT Pro micro weather stations are distributed by http://www.iot.nc​ in New Caledonia. Please email contact@iot.nc for more information.

MeteoHelix® weather station watching over the international Pohoda music festival

The Pohoda music festival weather will not only be monitored by the SHMU but also by the ultra-precise MeteoHelix® IoT Pro weather station connected to the international Sigfox wireless network operated by SimpleCell Slovakia. Being the only micro-weather station capable of providing accurate meteorological data in all climates and weather conditions, the MeteoHelix and its about to be released MeteoWind® Compact IoT are perfectly suited for monitoring crowded and vandalism-prone places such as music festivals and inner cities.

With heat indexes climbing every year, it is important for music festival officials to have accurate data on air temperature and humidity and also on the intensity of solar irradiation to prevent heat strokes and other heat-induced emergencies.

For detailed weather information including weather forecast for the next 24 hrs at the Pohoda music festival, please see the following link:

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