Development and testing of several lunar-photometer prototypes and the new Triple (Sun-LunarSky) CE318-T photometer.
Development and testing of several lunar-photometer prototypes (i.e. modified CE318-N and CE318-U) capable of measuring aerosols and column water vapour during the night period, has been performed at Izaña station in collaboration with Cimel Electronique . The final version, the CE318-T, is able to perform daytime and nighttime photometric measurements using the sun and the moon as light source. This new device permits a complete cycle of diurnal aerosol and water vapour measurements valuable to enhance atmospheric monitoring. Two new methodologies to transfer the calibration from a reference instrument using only daytime measurements (Sun Ratio and Sun -Moon gain factor techniques) have been developed and evaluated. These methods allow the reduction of the previous complexities inherent to nocturnal calibration. A quantitative estimation of CE318-T aerosol optical depth (AOD) uncertainty by means of error propagation theory during daytime and night period has been assessed. A subsequent performance evaluation including CE318-T and collocated measurements from independent reference instruments has served to assess the CE318-T performance, day and night, as well as to confirm its estimated uncertainty.
The CE318-T has been recently adopted by NASA AErosol RObotic NETwork (AERONET) as the new standard instrument of the network. See Barreto et al. (2016).