Nocturnal Aerosol Monitoring at Roque de los Muchachos high-altitude station: Lunar Product Comparison

Lunar photometry is an emerging technique capable of filling the gaps in aerosol monitoring at night-time. This is particularly crucial in high latitudes and polar regions due to the prolonged absence of solar illumination. One of the most principal obstacles we encounter in monitoring aerosols at night-time using the Moon as a light source is the need for accurate extraterrestrial lunar irradiance due to the fast change of the Moon’s illumination over time. The RIMO (ROLO Implementation for Moon's Observation; Barreto et al., 2019) model is an implementation of the ROLO (RObotic Lunar Observatory) model. RIMO was performed by the polar aerosol community to estimate the AOD at night-time, transferring the calibration of the solar channels to nocturnal measurements by means of the Sun-Moon gain factor method. A further correction of the RIMO model, the so-called RIMO correction factor (RCF), has served to improve the accuracy of the lunar product (Román et al., 2020). Similar approaches to correct the ROLO or RIMO biases have been developed by AERONET and Skynet teams (Uchiyama et al., 2019). In this study, we will use an 11-month dataset of day- and night-time photometric measurements taken with the CE318-T photometer at Roque de Los Muchachos (La Palma, Canary Islands, Spain). This high-altitude observatory (2396 m above sea level) is an excellent location for astronomy and atmospheric observations. Day and night photometer observations performed at this pristine site are used to study and evaluate the differences between the AOD retrieved with the CE318-T photometer using RCF and AERONET lunar products.