The spectral deconvolution algorithm (SDA) whose output of fine and coarse mode optical depth is currently an AERONET product is reviewed with respect to recent findings which include an empirical demonstration of the rather subtle difference between FMF and SMF (fine mode fraction and sub-micron mode fraction). An extended spectral deconvolution algorithm (SDA+) which exploits the added information content of the new 1.64 um AERONET band will be discussed along with results from the recent UAE^2 experiment. Point of Contact: Thomas F. Eck NASA/GSFC GEST Code 614.4 Greenbelt, MD 20771 Tel.: (301) 614-6625 AERONET (AErosol RObotic NETwork) http://aeronet.gsfc.nasa.gov/