The objective is to provide a comprehensive assessment of the potential use of the very low-cost Calitoo-TENUM hand-held sun-photometer for operational dust model and satellite observation validation activities within the WMO SDS-WAS.

• Since February 2017, a Calitoo has been taking measurements in the heart of the Sahara Desert at the Tamanrasset World Meteorological Organization – Global Atmospheric Watch (GAW) station (Algeria) .

Figure 1.- AERONET AOD computed at 500 nm from Cimel sun-photometer versus AOD computed from CALITOO hand-held sun-photometer at Tamanrasset. The gap in data in 2018 is due to the replacement of the Calitoo for a newly calibrated one.

• Since March 2018, a Calitoo has been operating on board the oceanographic vessel “Ángeles Alvariño” from the Spanish Institute of Oceanography (IEO). This Calitoo is taking maritime measurements in the Atlantic Ocean, from Canary Islands to Galicia, as well as in the Mediterranean Sea, from Cataluña to Andalucía.

Figure 2.- Oceanographic vessel “Ángeles Alvariño”.

• Two Calitoos are currently being used in Iran in a pilot project in collaboration with the Islamic Republic of Iran Meteorological Organization (IRIMO). One in the urban Tehran megacity station since November 2016 to monitor aerosol pollution and the impact of dust outbreaks on the city. Another one has been taking measurements in the Mt. Aminabad (Firoozkoh) regional GAW station since January 2018.