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New Developments in the Retrieval of Tropospheric Ozone from GOME, SCIAMACHY and SEVIRI

Richard Siddans(1), Barry Latter(2), Caroline Poulsen(2) and Brian Kerridge(2)

(1) Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom
(2) Rutherford Appleton Laboratory, Chilton, OX11 0QX, United Kingdom

Abstract

Uv-vis nadir spectrometers, such as GOME and SCIAMACHY, provide height-resolved information on ozone spanning the troposphere and stratosphere. A well established scheme to extract this information from GOME data has been developed at RAL and has been applied to process the complete ERS-2 mission up to the tape-recorder failure in mid 2003. A new version of the processing scheme is currently being developed which will provide more accurate tropospheric information by modelling the effects of cloud and aerosol using results from ATSR-2 generated by the NERC GRAPE project. While this technique is providing valuable new insights into the distribution of tropospheric and lower stratospheric ozone, the quality of the tropospheric information in particular is limited. Retrieval simulations indicate that better resolution and precision in the troposphere could be obtained if the uv-vis observations are combined with measurements in the mid-infrared ozone band at 9.7 microns. In principal mid/upper tropospheric ozone should be clearly distinguishable from ozone in the lower troposphere / boundary layer. This additional information originates from differences in the sensitivities of the uv-vis and mid-ir to perturbations in ozone in the lower troposphere (the ir being relatively insensitive due to lack of thermal contrast with the surface, whereas uv-vis sensitivity extends to the ground). Several current and planned satellites include measurements in the 9.7 micron band including spectrometers such as METOP-IASI and imaging instruments such as MSG-SEVIRI.

This paper will (a) present an overview of the current state-of-the-art GOME/SCIAMACHY ozone profile retrieval scheme developed at RAL (b) report new results from a Eumetsat study which demonstrate for the first time the potential of a synergistic retrieval scheme to deliver enhanced information on tropospheric ozone by combining uv-vis measurements from GOME/SCIAMACHY with 9.7 micron observations from SEVIRI.

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry