Characterization of temperature sensitivity of sun photometers by field comparison with a reference instrument

The temperature sensitivity of sun photometers is mainly caused by the temperature dependency of detectors and filters. For the 1020 nm channel of the photometer CIMEL-318 the relative change in signal due to temperature is about 2.50E−3 °C−1. For other channels, this dependency is significantly lower. However, the uncertainty of the temperature coefficient, about 5.0E−4 °C−1, is a limitation to the improvement of the data quality. So as to get a better data quality, AERONET has begun to thermally characterize the response of each photometer by means of laboratory measurements in a thermally controlled chamber.In this work, we study the possibility of carrying out the thermal characterization of photometers, by comparison with a previously characterized sun photometer. Our goal is to develop a temperature correction method for checking temperature dependency of field photometers with no additional cost, using the measurements already performed during the radiometric calibration process. Furthermore, this method could be also used to obtain the temperature coefficients for archived data, for example, on photometers that were physically modified (filter or detector replaced).