Determination of automatic weather station self‐heating originating from accompanying electronics

Abstract

Atmospheric air temperature values are fundamental in meteorology and climate studies. To achieve high accuracy in the measurements, the features, characteristics and performances of instruments are of high importance. This study focuses on the most commonly used temperature sensors within automatic weather stations, with a specific focus on evaluating the self‐heating effect. Self‐heating in automatic weather stations originates not only from the temperature sensor itself but also from the electrical components housed together within. This effect introduces extra heating in the system, causing biases and errors in temperature records. The conducted measurements show the temperature change in the close vicinity of the thermometers over a time period of more than 66 hr with electric current and voltage supply values recommended by the respective sensor manufacturers. Furthermore, the temperature changes after increasing the voltage supply levels up to 80% of the maximum voltage recommended by the manufacturer are presented as well. The results of overall self‐heating indicated a +0.07°C increase in temperature for the tested sensors when using the manufacturers’ recommended electric current and voltage supply. However, the use of elevated voltage levels shows a considerably higher temperature increase in the vicinity of the temperature sensors. In the present study, the measured difference from the initial measured temperature can be as high as +0.32°C.

Metrological evaluation of the effect of the presence of a road on near‐surface air temperatures

“…In the present work, however, all the shields were new, employed for the same amount of time and exposed to the same homogeneous environmental conditions, causing a similar level of dirtiness. Any potential error induced by shield ageing is shared by all the stations, cancelling out during the calculation of temperature differences. Sensor self‐heating: Many literature works deal with the self‐heating evaluation of a platinum resistor in high‐quality laboratory measurements (Batagelj et al ., 2003; Coppa and Merlone, 2016), but very few are directed towards the same evaluation for meteorological measurements (Pavlasek et al ., 2020). The latter, investigating common meteorological temperature sensors, found temperature uncertainties due to self‐heating up to 0.2 °C: in our case, all the were sensors identical and powered by the same datalogger, so self‐heating do not alter the relative readings among them. Surface features: Changes in surface reflectivity can affect sensors, which are shielded against direct sun radiation but not against radiation reflected from the ground (Musacchio et al ., 2019).…”

“…Any potential error induced by shield ageing is shared by all the stations, cancelling out during the calculation of temperature differences. • Sensor self-heating: Many literature works deal with the self-heating evaluation of a platinum resistor in high-quality laboratory measurements (Batagelj et al, 2003;Coppa and Merlone, 2016), but very few are directed towards the same evaluation for meteorological measurements (Pavlasek et al, 2020). The latter, investigating common meteorological temperature sensors, found temperature uncertainties due to selfheating up to 0.2 C: in our case, all the were sensors identical and powered by the same datalogger, so selfheating do not alter the relative readings among them.…”

Thermal metrology for climate: a review of projects, activities and open issues

“…The MeteoMet consortium has grouped close to 100 participants: almost all National Metrology Institutes (NMIs) in Europe took part as funded partners, more than 10 Universities, 20 among public and private Research Institutes, several private companies and manufacturers in the status of collaborators, International Institutions (the WMO, the GCOS, the Ny-Ålesund Science Committee, about 20 NMHSs and others). MeteoMet accounted for around 300 identified deliverables: new laboratory and transportable calibration systems [4][5][6][7], improved knowledge in scientific investigation of environmental quantities and their effects on instruments [8,9], on site campaigns also in remote areas such as high mountains and the Arctic [10,11], procedures and intercomparisons, technical advances in sensors and measurements methods [12][13][14], evaluation of uncertainties and instrumental in climate and meteorological measurements and data series [15][16][17], evaluation of climate records [18], discussion on reference grade measurements [19,20], training and dissemination.…”

“…This effect introduces extra heating in the system, causing biases and errors in temperature records. Measurements have been conducted in the framework of a research mobility grant linked to the Meteo-Met project, to evaluate the self-heating in modern sensors normally used in automatic weather stations [12]. The study was carried on providing to the sensors the current and voltage supply values recommended by the respective sensor manufacturers.…”

Non-Contact Thermometer for Improved Air Temperature Measurements

“…A number of experiments and studies have already investigated specific aspects of atmospheric air temperature measurements, quantities of influence, and uncertainty components. During the MeteoMet projects [ 13 , 14 ] some of these effects were evaluated mainly in terms of single components in the overall measurement uncertainty budget: sensor dynamics, direct and reflected radiation [ 15 , 16 ], self-heating of meteorological sensors [ 17 ], and wind and rain.…”