Multi-decadal NDACC Measurements of Trace Species in the Arctic Free Troposphere

Abstract:

To understand better the effects of changing emissions, possibly changing transport pathways and chemistry in a rapidly changing Arctic tropospheric environment, consistent observations of key species for a duration preceding and spanning our current time period are invaluable. Since the late 1990's observations have been taken in the Arctic at several NDACC sites (Network for the Detection of Atmospheric Composition Change). These FTIR (Fourier Transform Infra-Red) instruments that pass through a process of inter-comparison to maximize consistency of spectral data and retrievals, routinely acquire spectra for many species of import to both tropospheric and stratospheric transport and chemistry. We will focus on the time series of several species of varying lifetimes, and emission rates to investigate transport to the Arctic. These time series of species with shorter lifetimes will include C₂H₂, C₂H₆ and HCN. Those with longer lifetimes include CO, CH₄, CCl₂F₂ and CCl₄. The vertical sensitivity of the FTIR measurements will be described for each to show the levels in the atmosphere from which the information is derived. The annual cycles and changes in concentrations with time will be discussed.