cientific Problem: The Pasadena site at the California Institute of Technology was one of several ground sites involved in the NOAA CalNex field study concerning air quality and climate change. Aerosol samples were collected during this field campaign, to be analyzed using Fourier Transform Infrared (FTIR) spectroscopy analysis. Using the FTIR measurements, we hope to identify what sort of organic compounds are present in the ambient air, and then make inferences about potential sources by comparing with areas of known aerosol composition. This field study is important in helping to assess the air quality of Pasadena and to contribute to the present knowledge of atmospheric processes over California.