IT IS RECOGNIZED THAT TROPOSPHERIC AEROSOLS PLAY AN IMPORTANT ROLE IN AFFECTING THE EARTH'S CLIMATE IN PARTICULAR BY SCATTERING AND ABSORBING SOLAR RADIATION LEADING TO A COOLING AND WARMING EFFECT RESPECTIVELY ALTHOUGH THERE IS A LARGE DEGREE OF UNCERTAINTY IN MEASUREMENTS PERTAINING TO THE OPTICAL PROPERTIES OF AEROSOLS. PART OF THIS UNCERTAINTY STEMS FROM PREVIOUS ASSUMPTIONS OF ORGANIC AEROSOLS WHICH MANY MODELS ASSUMED ORGANIC AEROSOL TO BE FORMED SOLELY FROM GAS-PHASE REACTIONS AND TO BE PURELY SCATTERING. THIS IS KNOWN TO BE FALSE HOWEVER AS IT HAS BEEN FOUND THAT SOME ORGANIC AEROSOL IS CAPABLE OF ABSORBING LIGHT COMMONLY KNOWN AS BROWN CARBON (BRC). ONE FAMILY OF MOLECULES CAPABLE OF PRODUCING BRC INCLUDES ALPHA-DICARBONYLS WHICH CAN UNDERGO AQUEOUS-PHASE REACTIONS WITH NITROGEN COMPOUNDS TO FORM BROWN CARBON AEROSOL. IN ORDER TO MEASURE THE OPTICAL PROPERTIES OF BRC GENERATED FROM ALPHA-DICARBONYLS AEROSOL WILL BE GENERATED WITHIN A REACTION CHAMBER AND STUDIED USING CAVITY RING DOWN SPECTROSCOPY (CRD) AND PHOTOACOUSTIC SPECTROSCOPIES (PAS). BY USING CRD AND PAS IN CONJUNCTION EXTINCTION AND ABSORBANCE MEASUREMENTS CAN BE OBTAINED FOR DIFFERENT AEROSOLS WHICH WILL ALLOW FOR THE DETERMINATION OF THE COMPLEX REFRACTIVE INDEX FOR VARIOUS BRC PRODUCTS A PARAMETER WHICH CAN BE UTILIZED IN ATMOSPHERIC MODELS WHEN MODELING THE INTERACTION OF AEROSOLS WITH LIGHT. OTHER TECHNIQUES INCLUDE THE USE OF A RAMAN MICROSCOPE AND AEROSOL MASS SPECTROMETRY TO DETERMINE THE MORPHOLOGY AND COMPOSITION OF THE AEROSOL RESPECTIVELY. IN ADDITION TO MEASURING THE COMPLEX REFRACTIVE INDEXES OF VARIOUS BRC PRODUCTS THE EFFECT OF HUMIDITY CHEMICAL OXIDATION AND PHOTOOXIDATION REACTIONS ON THE OPTICAL PROPERTIES OF BRC WILL BE EXPLORED BY ALTERING THE REAGENTS AND CONDITIONS OF THE REACTION CHAMBER BETWEEN DIFFERENT EXPERIMENTS AND BY OXIDIZING THE AEROSOL WITHIN A FLOWTUBE. BY DETERMINING COMPLEX REFRACTIVE INDEXES OF VARIOUS BRC PRODUCTS AS WELL AS WHAT OTHER FACTORS INFLUENCE THE FORMATION AND ABSORPTIVE PROPERTIES OF BRC CURRENT ATMOSPHERIC MODELS WILL ABLE TO NOT ONLY MORE ACCURATELY PREDICT CURRENT CLIMATE CONDITIONS BUT ALSO MORE ACCURATELY PREDICT FUTURE CLIMATE CHANGE.