Polar regions play an important role in the globally linked climate system. Observations of antarctic stratospheric ozone depletion provide ample evidence of the uniqueness of polar atmospheric chemistry owing to extreme cold and prolonged darkness. During the winter and spring months, the arctic troposphere contains elevated concentrations of aerosols and gases which are transported from lower latitudes. Little is known about the chemical processing and removal of the gas phase constituents. The nitrogen oxides are a primary factor in controlling the tropospheric level of ozone. Tropospheric ozone, in turn, is believed to be increasing in the northern hemisphere. Consequently, understanding the chemistry of the reactive nitrogen species is important. This project will measure the abundance of several gaseous nitrogen species including nitric oxide, nitric acid, total reactive odd nitrogen, and peroxyacetyl nitrate. These measurements will be complemented with determination of nitrate concentrations in aerosols, rain, snow, and snowpack. Three primary questions will be addressed: (1) What are the concentrations of various nitrogen oxide species with respect to meteorological and temporal variations in central Alaska? (2) What is the chemical processing of these species and how is it related to ozone concentrations? and (3) How important is wet and dry deposition as a removal mechanism for these species in central Alaska?
