High spectral-resolution infrared solar transmission spectra contain information about the vertical distribution of the absorbing species in the terrestrial atmosphere due to the pressure broadening of the absorption lines. This feature is being exploited in the Infrared Working Group to retrieve vertical profile information of several atmospheric trace gases, such as O3, CO, N2O, CH4, HCl, HF, HNO3, C2H6 and HCN, in addition to the total column abundances.
A highly variable interference has long been considered the dominant feature of water vapor for practitioners who retrieve atmospheric total column amounts and profiles from infrared solar absorption spectra. Due to the importance of water as a greenhouse gas and its possible long-term trend resulting from changes in the atmosphere and subsequent feedback effects there is renewed effort in extracting water vapor quantities from archived solar spectra, which for some sites stretch back to the 1970's.
In the period from June–July 2009, a large scale intercomparison of UV-Visible spectrometers took place at the Cabauw meteorological observatory, a semi-rural site located in the Netherlands, 30 km South of Utrecht.
Despite its low abundance in the atmosphere, stratospheric bromine contributes up to 25% to the global ozone loss due to its high ozone depletion potential [e.g., World Meteorological Organization (WMO), 2007]. The main sources of bromine in the stratosphere are natural and anthropogenic long-lived and very short-lived brominated organic compounds [e.g., Pfeilsticker et al., 2000; Salawitch et al., 2005]. Long-term observations by in-situ ground-based networks have revealed a decline in total organic bromine from long-lived species by 3 to 5% during the 1998-2004 period [WMO, 2007].
At the 2008 NDACC Steering Committee meeting, a decision was made to remove the "Primary" and "Complementary" designations of NDACC measurement sites / stations. These original terminologies were instituted at the inception of the Network for designating a minimum of five stations with long-term measurement commitments, representing the major geographical regions of the globe (i.e., Arctic, Northern Hemisphere (NH) Midlatitudes, Tropics, Southern Hemisphere (SH) Midlatitudes, and Antarctic).