The BAO tower site is operated by NOAA ESRL. A wide variety of instruments and investigators from multiple national laboratories and universities will be based at this site. LIDAR instruments will provide measurements of ozone, aerosols and meteorological data. Ground-based instruments will provide measurements of volatile organic compounds, peroxyacetyl nitrates, sulfur dioxide and ozone production rates. In-situ instruments on the 300 m tower will provide vertical profiles of ozone, reactive nitrogen species, gas phase acids and oxygenated VOCs, ammonia, methane, carbon dioxide, aerosol size distributions and extinction. In addition, the BAO will provide one base of operations for mobile laboratories that can make chemical and aerosol measurements across the Front Range domain. The overall goal of this effort is to understand sources, transport and chemical transformations of air pollutants, particularly those that lead to ground level ozone.