The retrieval of oxygenated volatile organic compounds by remote sensing techniques

Abstract

This work describes global measurements of the trace gas formaldehyde derived from stray light spectra in the ultraviolet region measured by the satellite instruments GOME and SCIAMACHY along with ground-based MAX-DOAS instruments. The analysis was carried out using the method of the Differential Optical Absorption Spectroscopy (DOAS). The work complementarily presents the first measurements of the trace gas glyoxal in the visible wavelength region. New algorithms to derive vertical columns of the satellite instruments are developed and described. For the ground-based geometry a way was found to derive profile information for the tropo-spheric absorbers. This work therefore contributes fundamentally to an improvement in the understanding of the chemistry of the troposphere. It offers the opportunity to obtain a better estimate on the sources and sinks of hydrocarbons in the atmosphere. Particularly, a number of case studies illustrates the significance of biogenic emissions and of biomass burning for the global distribution of the oxygenated volatile organic compounds. A comparison with results from a global atmosphere model shows only a moderate agreement in many regions of the earth. This reflects the limited state of knowledge at present about the very complex physical and chemical processes in the troposphere.