9521767 Minschwaner This project will be a continuation of the 18-year hydroxyl radical (OH) observation record at Fritz Peak, Colorado. Ground-based measurements of the resonant absorption of sunlight at 308 nm are performed to yield atmospheric OH column amounts. OH is one of the most chemically active constituents in the atmosphere. The photochemistry of OH is intimately connected to the budget of stratospheric ozone and is a major factor in the efficiency of ozone destruction by nitrogen and chlorine compounds. Measurements of OH are crucial to understanding natural and anthropogenic change in the Earth's atmosphere. In addition to the continued measurements at Fritz Peak, a second, similar instrument will be refurbished at New Mexico Institute of Mining and Technology and intercompared with the Fritz Peak as well as other instruments. Modeling and analysis will be carried out on the new data as well as the existing record in order to better understand the seasonal and long-term behavior of OH and its interrelationship with other changes in composition of the atmosphere.
