ATMOSPHERIC AEROSOLS PERTURB THE ENERGY BUDGET BY ABSORBING AND SCATTERING SOLAR RADIATION. ESTIMATES OF DIRECT AEROSOL RADIATIVE FORCING REMAIN IN DEBATE AS INCONSISTENT VALUES HAVE BEEN RETRIEVED FROM SATELLITE OBSERVATIONS AND DERIVED BY GLOBAL CLIMATE MODELS. CONSEQUENTLY DIRECT AEROSOL-RADIATION INTERACTIONS ARE ONE OF THE LARGEST UNCERTAINTIES IN CLIMATE MODELS. THE VARIABILITY IN THE SPATIOTEMPORAL DISTRIBUTION OF PARTICLES AND THE DEPENDENCE OF OPTICAL PROPERTIES ON PARTICLE COMPOSITION SIZE MORPHOLOGY AND AGE MAKES THE INTERACTION DIFFICULT TO QUANTIFY. IN MY GRADUATE WORK I AIM TO IMPROVE THE UNDERSTANDING OF DIRECT AEROSOL-RADIATION INTERACTIONS BY RETRIEVING THE COMPLEX REFRACTIVE INDEX OF ATMOSPHERIC AEROSOLS WITH FULL UV-VIS SPECTRAL COVERAGE. THE OBSERVATION OF AN ENSEMBLE OF ATMOSPHERIC AEROSOLS IS AN ATTRACTIVE APPROACH BECAUSE THE OVERALL OPTICAL PROPERTIES OF A DIVERSE PARTICLE POPULATION CAN BE RETRIEVED AND USED TO REPRESENT A REGIONAL ATMOSPHERE IN RADIATIVE TRANSFER CALCULATIONS. STATE OF THE ART INSTRUMENTS ARE IN DEVELOPMENT AND WILL YIELD MEASUREMENTS OF THE ABSORPTION AND EXTINCTION COEFFICIENTS OF AN ENSEMBLE OF ATMOSPHERIC AEROSOLS WITH HIGH ACCURACY AND UNPRECEDENTED SPECTRAL COVERAGE. A NOVEL METHOD FOR RETRIEVING THE AEROSOL COMPLEX REFRACTIVE INDEX HAS BEEN FORMULATED TO TAKE ADVANTAGE OF THE INSTRUMENTS SPECTRAL COVERAGE. THE SPECTRUM OF RETRIEVED AEROSOL COMPLEX REFRACTIVE INDEX CAN BE EASILY ASSIMILATED INTO RADIATIVE TRANSFER CALCULATIONS AND WILL ACCURATELY REPRESENT THE SOUTHEASTERN US. MEASURED QUANTITIES IN THE RETRIEVAL WILL ALSO BENEFIT THE GENERATION OF LOOK-UP TABLES USED TO RETRIEVE AEROSOL OPTICAL PROPERTIES FROM SATELLITE OBSERVATIONS