1Centro Andaluz de Medio Ambiente (CEAMA), Universidad de Granada, Junta de Andalucía, Av. del Mediterráneo s/n, 18006 Granada, Spain
2Departamento de Física Aplicada, Universidad de Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
3Mesoscale Atmospheric Processes Laboratory, NASA Goddard Space Flight Center, Greenbelt, 20771, Maryland, USA
Received: 06 Jan 2012 – Discussion started: 17 Feb 2012
Abstract. This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, δAe(λ), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of δAe(λ) and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable δAe(λ) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16° N, 3.60° W, 680 m a.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.
Revised: 06 Jun 2012 – Accepted: 11 Jun 2012 – Published: 11 Jul 2012
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Pérez-Ramírez, D., Lyamani, H., Olmo, F. J., Whiteman, D. N., Navas-Guzmán, F., and Alados-Arboledas, L.: Cloud screening and quality control algorithm for star photometer data: assessment with lidar measurements and with all-sky images, Atmos. Meas. Tech., 5, 1585-1599, doi:10.5194/amt-5-1585-2012, 2012.