Limb-Nadir Matching for Tropospheric NO2: A New Algorithm in the SCIAMACHY Operational Level 2 Processor

Kurzfassung

SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) aboard ESA's environmental satellite ENVISAT observed the Earth's atmosphere in limb, nadir, and solar/lunar occultation geometries covering the UV-Visible to NIR spectral range. Limb and nadir geometries were the main operation modes for the retrieval of scientific data. The new version 6 of ESA's level 2 processor now provides for the first time an operational algorithm to combine measurements of these two geometries in order to generate new products. As a first instance the retrieval of tropospheric NO2 has been implemented based on IUP-Bremen's reference algorithm [1]. We will detail the single processing steps performed by the operational limb-nadir matching algorithm and report the results of comparisons with the scientific tropospheric NO2 products of IUP and TEMIS [2]. The operational limb-nadir matching has been programmed in a generic way, meaning that the application to further trace gas species will require moderate adaptations only. Retrieval of tropospheric BrO by limb-nadir matching is planned for the next operational processor version. References: [1] A. Hilboll, A. Richter, A. Rozanov, Ø. Hodnebrog, A. Heckel, S. Solberg, F. Stordal, and J. P. Burrows. Retrieval of tropospheric NO2 columns from SCIAMACHY combining measurements from limb and nadir geometries. Atmos. Meas. Tech. Discuss., 5, 5043-5105, 2012. [2] K. F. Boersma, H. J. Eskes and E. J. Brinksma: Error Analysis for Tropospheric NO2 Retrieval from Space. J. Geophys. Res., 109 D04311, 2004.