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).


Figure.- Cimel masters of the AERONET-Europe Transnational Access (TNA) Calibration Facility.