Aerosols both scatter and absorb incoming solar radiation, influencing Earth's climate. Recent developments of visible cavity ring-down and photoacoustic instruments have enabled new and detailed understanding of ambient aerosol optical properties. We have undertaken the development of broadband aerosol extinction (= absorption + scattering) at short wavelengths using cavity enhanced spectrometers with LED and other light sources. This instrument concept provides spectrally resolved measurements over a wavelength range where some aerosol species, such as "brown carbon", may have wavelength dependent absorption. The instrument has recently participated in measurements at the U.S. Forest Service Fire Lab (FLAME IV), at the SOAS campaign in the southeast U.S., and through a collaborative project with Dr. Yinon Rudich at the Weizmann Institute of Science.