Dual temperature sensors with different emissivities in radiosondes for the compensation of solar irradiation effects with varying air pressure

Abstract

ABSTRACT:One of the challenges in temperature measurements in the upper air using a radiosonde is the correction of solar radiation effects. A prerequisite for the correction is in situ measurements of solar radiation. In this study, a new technique for the measurement of solar irradiation followed by the temperature correction was developed using dual temperature sensors with different emissivities. The principle is that the radiation intensity is calculated by using the temperature difference between two thermistors coated with different materials (one with graphite and the other with aluminium) and then the irradiance obtained is used for the correction. As a first stage, the effect of air pressure on the temperature correction process using dual thermistors was examined. The temperature difference between the two sensors was found to be linearly proportional only to the irradiance up to 360 W m −2 , regardless of air pressure from 10 to 1000 hPa at room temperature. This provides a way to calculate the irradiance by simply measuring the temperature difference between the two sensors. The calculated irradiance showed a difference of less than 45 W m −2 (13% of the maximum irradiance) compared to the irradiance measured with a calibrated pyranometer. The extended uncertainty of the calculated irradiance was 53.5 W m −2 (coverage factor k = 2). A reference temperature sensor in the shade was used to obtain a correction formula as a function of air pressure and calculated irradiance. When the temperature was corrected using the calculated irradiance, the extended uncertainty of the corrected temperature was 0.98 K (k = 2).

Correction of solar irradiation effects on air temperature measurement using a dual‐thermistor radiosonde at low temperature and low pressure

“…This paper investigates the combined effect of low temperature and low pressure on radiosonde temperature sensors under irradiation for the calculation of irradiance and followed by the correction of heat‐biased temperature using dual thermistors with different emissivities. The concept of using dual thermistors was previously demonstrated for obtaining irradiance at varied air pressure (Lee et al ., ). In this study, air temperature and air pressure are simultaneously varied from 25 to −80 °C and from 100 to 1 kPa, respectively at the extended irradiance of about 1500 W m −2 under no artificial ventilation.…”

Reply on RC1

“…As previously observed, the variation of the other parameters results in a change in only the slope of the linear functions, and the linearity is not altered (Lee et al, 2018c;Lee et al, 2018b). Because all the experiments performed in this study adopt a fixed S0 = 980 W•m -2 and the empirical fitting coefficients are accordingly obtained, the effect of the irradiation intensity can be incorporated into Eqs.…”

Development of upper air simulator for the calibration of solar radiation effects on radiosonde temperature sensors

“…To investigate the effect of each environmental parameter on the compensation of radiation effects, one parameter of the UAS was systematically varied while keeping the others fixed. As an exception, only irradiance was fixed at S = 900 W·m −2 throughout the study because the linearity between the temperature rise of the sensors and irradiance, independently of the other parameters, has been documented in the literature (Lee et al ., , ). In these reports, the other parameters were found to affect only the co‐efficient of proportionality between the temperature rise and irradiance.…”