ATMOSPHERIC AEROSOLS ARE PARTICLES SUSPENDED IN THE ATMOSPHERE. THEY ABSORB AND SCATTER RADIATION AND ALSO ACT AS CLOUD CONDENSATION NUCLEI ENHANCING CLOUD COVER. THESE PROPERTIES DIRECTLY IMPACT EARTH S RADIATION BALANCE BY ALTERING HOW MUCH SOLAR RADIATION IS ABSORBED AND REFLECTED BY THE ATMOSPHERE AND ARE DETERMINED BY THE CHEMICAL COMPOSITION OF THE AEROSOL PARTICLE. THE BULK OF THE UNCERTAINTY ASSOCIATED WITH THIS IMPACT RESULTS FROM LACK OF KNOWLEDGE OF SOURCES OF THE AEROSOL COMPONENTS AND THE LARGEST UNCERTAINTY IS SHOWN BY SECONDARY ORGANIC AEROSOL (SOA). THIS WORK PROPOSES TO STUDY 2-OXOCARBOXYLIC ACIDS (2-OCAS) AS SOURCES OF SOA BY PERFORMING INDIRECT PHOTOLYSIS ON THE MODEL 2-OCAS PYRUVIC AND GLYOXYLIC ACID. THE MECHANISMS OF SOA FORMATION WILL BE DETERMINED THROUGH ANALYZING THE PRODUCTS OF THESE REACTIONS BY 1) ION CHROMATOGRAPHY COUPLED TO MASS SPECTROMETRY (IC-MS); 2) 2 4-DINITROPHENYLHYDRAZINE (DNPH) DERIVATIZATION FOLLOWED BY LIQUID CHROMATOGRAPHY COUPLED TO MASS SPECTROMETRY (UHPLC-MS); AND 3) HIGH FIELD 1H AND 13C NUCLEAR MAGNETIC RESONANCE (NMR). THE MODEL SOLUTIONS WILL ALSO BE STUDIED BY UVVISIBLE AND FLUORESCENCE SPECTROPHOTOMETRY TO MAP HOW THE OPTICAL PROPERTIES OF AEROSOLS CHANGE DURING INDIRECT PHOTOCHEMICAL AGING. FINALLY THE RESULTS OF THESE EXPERIMENTS WILL BE COMPARED TO FIELD SAMPLES COLLECTED BY THE NASA LANGLEY AEROSOL RESEARCH GROUP EXPERIMENT (LARGE) DURING THE NORTH ATLANTIC AEROSOLS AND MARINE ECOSYSTEMS STUDY (NAAMES). THIS WORK WILL MAKE A SIGNIFICANT CONTRIBUTION TO THE UNDERSTANDING OF SOURCES OF AEROSOL AND HOW ATMOSPHERIC AEROSOL COMPOSITION CHANGES DURING INDIRECT PHOTOLYSIS BY LINKING REAL IN-CLOUD PROCESSING TO LABORATORY MODELS.