Aerosol Optical Thickness in the Presence and Absence of African Dust using AERONET and Microtops II Sunphotometers

As part of the Puerto Rico African Dust and Cloud Study (PRADACS) Project, we present a comparison of the aerosol optical thickness (AOT) between the AERONET sunphotometer (CIMEL Electronique 318A) located at Cape San Juan (CSJ, 18° 23' N, 65° 37' E), Puerto Rico, and the radiometers (Microtops II) of the Arecibo Observatory. Data were collected at CSJ during the summer period of 2011, when African dust was present most of the time. Preliminary results showed, for both instruments, AOT values around of 0.4 when there were high concentrations of African dust over the island Puerto Rico. The AOT correlations between the two instruments were very good, with a slope of 0.8 and r2 of 0.9 for all wavelengths. The main differences observed were on the values above 0.6. We will show the temporal behavior of AOT for the two instruments and the spatial differences between them.