This award will provide logistical support for a period of five years to the NOAA Aeronomy Laboratory to make measurements from McMurdo and Palmer Stations in Antarctica, and to provide some logistical help in Thule, Greenland. Ground-based visible and ultraviolet spectroscopy will be used to measure stratospheric column abundances of ozone (O3), nitrogen di (and tri) oxide (NO2 and NO3), chlorine dioxide (OClO) and bromine monoxide (BrO). The simultaneous measurements of these gases, and their seasonal and diurnal variations, are of particular value in studying the polar ozone holes and the photochemistry which is responsible for the destruction of ozone. This project is important for the study of manmade effects on global change.