Averaging kernels for DOAS total-column satellite retrievals

[摘要] The Differential Optical Absorption Spectroscopy (DOAS) method is usedextensively to retrieve total column amounts of trace gases based on UV-visible measurements of satellite spectrometers, such as ERS-2 GOME. Inpractice the sensitivity of the instrument to the tracer density is stronglyheight dependent, especially in the troposphere. The resulting tracer profiledependence may introduce large systematic errors in the retrieved columns that are difficult to quantify without proper additional information, asprovided by the averaging kernel (AK). In this paper we discuss the DOAS retrieval method in the context of the general retrieval theory as developed byRodgers. An expression is derived for the DOAS AK for optically thin absorbers. It is shown that the comparison with 3Dchemistry-transport models and independent profile measurements, based on averaging kernels, is no longerinfluenced by errors resulting from a priori profile assumptions. The availability of averaging kernelinformation as part of the total column retrieval product is important forthe interpretation of the observations, and for applications like chemicaldata assimilation and detailed satellite validation studies.

[学科分类] 大气科学