Musat, Ileana CristinaThis is a study about the possibility of determining the aerosol optical depth by using star broadband observations from a whole sky imager. The main difficulty in such measurements consists of accurately separating the star flux value from the non-stellar diffuse light, which is overwhelmingly present in the whole sky imagery. A correction method to solve this problem is found and the monochromatic extinction at the ground due to aerosols is extracted from heterochromatic measurements. A form of closure is achieved by comparison with simultaneous or temporally close measurements with other instruments. The accuracy and precision of the method are assessed: the total error is a combination of random error of measurements and systematic error of calibration and model and is between 2.6 and 3% rms.en-USDissertationPhysics, Atmospheric Science