Ground-based FTIR measurements of Antarctic trace gases

Ground-based long path FTIR hyper-resolution spectroscopy was employed to measure solar absorption spectra at Arrival Heights, Antarctica during nearly the entire 1998–1999 daylight season. The spectra were analyzed to retrieve vertical total column amounts and volume mixing ratio (VMR)profiles for each of five atmospheric trace gases: HCl, HF, CH₄, N ₂O and O₃. HCl is a major reservoir for free atomic chlorine that directly destroys ozone within the Antarctic stratosphere. This was the first time that these gases were measured over such a long period of time in Antarctica, from just after seasonal sunrise to the approach of sunset.; Two analytical tools were used to analyze the absorption microwindows cut from the spectra measured with the University of Denver instrument called SORTI: SFIT-1 that retrieved the vertical column amounts for each of the five trace gases, and SFIT-1-plus-PROFIT that in addition to retrieving the total column amounts for each gas, also retrieved vertical VMR profiles extending from the surface up to an altitude of 80 km.; The column amounts and VMR's for each tract gas were assessed for temporal behavior throughout the daylight season. The seasonal losses of HCl due to heterogeneous chemistry were measured. The springtime depletion of ozone within the stratosphere was measured along with its subsequent recovery during the summer and autumn seasons.; An extensive error analysis was conducted for each trace gas employing the measured random errors and systematic errors to obtain the relative uncertainty associated with each total column amount calculated. A correlation analysis was performed to determine the inter-relationships among eleven physical and dynamic parameters that included total column amounts for each trace gas, the temperature and height of the Antarctic tropopause, and the potential vorticity obtained for each of four stratospheric altitudes.; Historical comparisons of the total column abundances measured during this study were made with previous Antarctic measurements obtained at the same location from 1986 through 1989. These comparisons were also made with the same data derived from the Arctic atmosphere for 1993 through 1997. It was concluded that the spring ozone amounts were continuing to decrease from 1995 through 1998.