The primary objective of RETRO was to understand, detect and assess long-term changes and interannual variability of the tropospheric chemical composition over the last 40 years, thereby providing the essential framework within which to understand possible future changes. The project employed five sophisticated global chemistry transport models (CTMs; two of them were general circulation models) and a variety of data sets from ground based, air and space borne measurements, which were assessed in terms of their quality and consistency.
Specifically, RETRO aimed at
A key deliverable are gridded long-term monthly mean time series of concentrations, emissions, and deposition fluxes for important tropospheric trace gases and aerosol species that reflect our best estimates of the atmospheric composition and the magnitude of constituent sources and sinks. These data sets are available on the RETRO ftp server or from the co-ordinator upon request.