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SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) is a scanning nadir and limb spectrometer covering the wavelength range from 212 nm to 2386 nm in 8 channels. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002 on the ENVISAT platform. After the platform failure in April 2012, SCIAMACHY is now in the postprocessing phase F. SCIAMACHY�s originally specified in-orbit lifetime was double the planned lifetime. SCIAMACHY was designed to measure column densities and vertical profiles of trace gas species in the mesosphere, in the stratosphere and in the troposphere (Bovensmann et al., 1999). It can detect a large amount of atmospheric gases (e.g. O3 , H2CO, CHOCHO, SO2 , BrO, OClO, NO2 , H2O, CO, CH4 , among others ) and can provide information about aerosols and clouds. The operational processing of SCIAMACHY is split into Level 0-1 processing (essentially providing calibrated radiances) and Level 1-2 processing providing geophysical products. The operational Level 0-1 processor has been completely re-coded and embedded in a newly developed framework that speeds up processing considerably. In the frame of the SCIAMACHY Quality Working Group activities, ESA is continuing the improvement of the archived data sets. Currently Version 9 of the Level 0-1 processor is being implemented. It will include An updated degradation correction Several improvements in the SWIR spectral range like a better dark correction, an improved dead & bad pixel characterisation and an improved spectral calibration Improvements to the polarisation correction algorithm Improvements to the geolocation by a better pointing characterisation Additionally a new format for the Level 1b and Level 1c will be implemented. The version 9 products will be available in netCDF version 4 that is aligned with the formats of the GOME -1 and Sentinel missions. We will present the first results of the new Level 0-1 processing in this paper.

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. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002. SCIAMACHY doubled its originally planned in-orbit lifetime of five years before the communication to ENVISAT was severed in April 2012, and the mission entered its post-operational phase. In order to preserve the best quality of the outstanding data recorded by SCIAMACHY, data processors are still being updated. This presentation will highlight three new developments that are currently being incorporated into the forthcoming Version 7 of ESA’s operational Level 2 processor: 1. Tropospheric BrO, a new retrieval based on the scientific algorithm of (Theys et al., 2011). This algorithm had originally been developed for the GOME-2 sensor and was later adapted for SCIAMACHY. 2. Improved cloud flagging using limb measurements (Liebing, 2015). Limb cloud flags are already part of the SCIAMACHY L2 product. They are currently calculated employing the scientific algorithm developed by (Eichmann et al., 2015). Clouds are categorized into four types: water, ice, polar stratospheric and noctilucent clouds. High atmospheric aerosol loadings, however, often lead to spurious cloud flags, when aerosols had been misidentified as clouds. The new algorithm will better discriminate between aerosol and clouds. It will also have a higher sensitivity w.r.t. thin clouds. 3. A new, future-proof file format for the level 2 product based on NetCDF. The data format will be aligned and harmonized with other missions, particularly GOME and Sentinels. The final concept for the new format is still under discussion within the SCIAMACHY Quality Working Group.

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. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002. SCIAMACHY doubled its originally planned in-orbit lifetime of five years before the communication to ENVISAT was severed in April 2012, and the mission entered its postoperational phase F. The SCIAMACHY Quality Working Group (SQWG) was established in 2007. The group coordinates evolution of algorithms and processors, aiming at improving the quality of the operational data products. University of Bremen (IUP), BIRA, DLR-IMF, SRON (Netherlands Institute for Space Research) and KNMI (The Royal Netherlands Meteorological Institute) are the members providing expertise in this group. In order to preserve the best quality of the outstanding data obtained by SCIAMACHY, data processors are still being updated. This presentation will highlight new developments that are currently being incorporated into the forthcoming Version 7 of ESA’s operational Level 2 processor

From its very beginnings the development of algorithms for the enumeration of chemical space was closely related to NASA's early exobiology activities. The complete and non-redundant generation of all connectivity isomers corresponding to a given molecular formula was part of the DENDRAL program, established in the mid-1960s. In the 1970s mathematicians provided new techniques to increase efficiency of the first approaches, and starting with the 1990's implementations became available as software packages for customary computers. Recently these methods have been rediscovered for application in astrobiology and origins of life research, particularly for generating and analyzing virtual chemical compound libraries of amino acids and nucleotide analogs.

Understanding the origins of life is a central question of Astrobiology. Computer methods offer unique means to approach this challenge. In order to obtain a better understanding of the selection rules which guided chemical and early biochemical evolution, our approach is to computationally generate exhaustive sets of biomolecule analogues, to calculate their physico-chemical properties, and to simulate adaptive processes that might have led to the biochemical foundations of life as we know it. Results on the amino acid alphabet will be presented and ongoing studies of nucleotide analogue libraries will be discussed.

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.

The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard Envisat observed the Earth’s atmosphere in nadir, limb and solar/lunar occultation geometries covering the UV-Visible to NIR (240-2380 nm) spectral range with a moderate spectral resolution of 0.2-1.5nm. The instrument provided decade long coverage (2002-2012) of various atmospheric parameters from the troposphere up to the mesosphere. These decadal datasets are important building blocks for long term assessments of climate relevance. The SCIAMACHY Quality Working Group (SQWG), formed in 2007, aims at improving the quality of the operational data products. University of Bremen (IUP), BIRA, DLR-IMF, SRON and KNMI are the members providing expertise in this group. Since the establishment of SQWG, the ESA operational Level 2 processor was significantly improved w.r.t. data quality and the product list was substantially enhanced with new parameters. The current project builds on the heritage of previous SQWG projects and has the following objectives: update the Level 0-2 processing chain, deliver the processor baseline enabling the generation of a quality controlled Level 1b and Level 2 dataset for the whole mission and to ensure long-term usability of the data. The SQWG Level 2 team is working on the improvement and implementation of processor Version 6 and the future Version 7. Under the SQWG framework, the main focus is on the following products: in nadir mode, total columns of O3, NO2, CO, IO and the tropospheric columns of NO2, and O3 (from limb-nadir matching) and the tropospheric columns of BrO and HCHO and, in limb, the aerosol and water vapour profiles and cloud flagging improvement and implementation. Here we present the key results of SCIAMACHY Level 2 Version 6 and Version 7 implementation and verification activities.

SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) was a scanning nadir and limb spectrometer covering the wavelength range from 212 nm to 2386 nm in 8 channels. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002 on the ESA's ENVISAT platform. After the platform failure in April 2012, the space agencies continue to support the operational product evolution in the frame of the SCIAMACHY Quality Working Group and Expert Support Laboratory. Note that SCIAMACHYs in-orbit lifetime was twice the planned lifetime. The instrument was designed to measure column densities and vertical profiles of trace gas species in the troposphere, in the stratosphere and in the mesosphere (Bovensmann et al., 1999). It can detect a wide range of trace gases and can provide information about aerosols and clouds. The operational processing of SCIAMACHY aims to deliver continuously high quality data products to the scientific community. It is split into Level 0-1 processing (essentially providing calibrated radiances) and Level 1-2 processing providing geophysical products. The operational Level 0-1 processor has been completely re-coded and embedded in a newly developed framework that speeds up processing considerably. A better degradation correction was implemented that now takes into account the dependence of transmission on the incidence angle of light on the mirror. The stray light correction now uses a matrix correction scheme for all channels. The handling of calibration data was completely overhauled: instead of using a collection of files we use a database that allows proper traceability of used calibration data for any given Earth measurement and that allows immediate quality checks. With the improved Level 1 products it is expected that the Level 2 products are also improved (see related contribution on operational Level 2 products from SCIAMACHY). Both datasets were re-processed. Here we will report on the quality of the Level 1 data. In addition future planned improvements such as a new bad pixel mask in the SWIR channel will be discussed.

Astrobiology is the study of the origin, distribution and future of life in the universe, biomolecules are molecules produced by living organisms. This talk reviews known facts and open questions about biomolecules in the context of Astrobiology and introduces a research project on "Creating a Reference Set of Amino Acids Structures for Use in Multiple Astrobiology Investigations" that tries to find answers using computational methods.

In sommer of 2010 version 6 of the SCIAMACHY operational processor is planned to be delivered to ESA. The SCIAMACHY Quality Working Group recommended an implementation of the formaldehyde (HCHO) and glyoxal (CHOCHO) vertical columns into version 6 of the off-line processor. They are formed during the oxidation of volatile organic compounds (VOCs) emitted by plants, anthropogenic activities, and biomass burning. Due to a rather short lifetime of formaldehyde and glyoxal, their distribution maps, obtained by the SCIAMACHY, represent the emission fields of their precursors, VOCs. The descriptions of reference algorithm as well as all the cross-sections for formaldehyde and glyoxal retrievals were delivered to DLR by the Belgian Institute for Space Aeronomy (BIRA) (I. De Smedt, 2008) and by the IUP (F. Wittrock, 2006), respectively. Both retrievals are based on the DOAS technique. For the formaldehyde retrieval the spectral region of 328.5-346 nm was recommended. The absorption cross-sections of HCHO, O3, NO2, BrO, OClO, a Ring spectrum and a polynomial of the fifth order are included into the fitting procedure. Before conversion to the vertical columns, the slant columns have to be normalized by subtracting the slant columns measured over Pacific ocean, where the only source of formaldehyde is methane oxidation. After the conversion to the vertical columns, part of HCHO removed during the previous procedure has to be re-added to the final vertical column by adding of the mean vertical column calculated by the tropospheric chemistry model IMAGES (J.-F. Müller, 1995). This normalization is necessary to compensate for the offset introduced by the solar reference measurements and interferences by other absorbers. For the determination of glyoxal columns, the spectral region 435-457 nm was selected. In this case, the absorption cross-sections of CHOCHO, O3, NO2, H2O, O4, a Ring spectrum and a cubic polynomial are included in the fitting procedure. The normalization of the CHOCHO slant columns is performed in the same way as for formaldehyde.

Limb measurements performed by the Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite enable a retrieval of stratospheric profiles for various trace gases on a global scale. The operational SCIAMACHY L1b-2 processor was developed on behalf of ESA at German Aerospace Center (DLR). The more sophisticated, so called “scientific”, version of the operational processor without any operational constraints is developed parallel and give us free hand for all sorts of experiments. In this paper we analyze different inversion models suitable for the ozone retrieval from SCIAMACHY limb measurement data. This analysis is performed by means of the scientific processor. The inversion algorithms comprise differential and absolute radiance models with multiple spectral windows as well as the radiance model together with Chappuis triplets. The sensitivity of the retrieval algorithm in dependance on the chosen inversion model is investigated and discussed. Since till now the operational ozone limb retrieval was performed up to 45 km only, special attention is given to the upper stratosphere (45 - 65 km). A large class of regularization methods as for instance, the Tikhonov regularization, the iteratively regularized Gauss-Newton method, the regularizing Levenberg-Marquardt method, the asymptotical regularization approach and the regularized total least-squares method can be used in the scientific processor. Their efficiency is tested and test results are presented in the paper. The impact of a Picard iteration model for simulating the radiating transfer in a two-dimensional spherical shell atmosphere is also discussed.

Due to the strict requirements regarding the computation time, the off-line processor of the SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY) instrument is forced to operate with several approximations. These approximations are incorporated in both the forward and the inversion models. Here we would like to investigate the impact of these approximations. The main simplification which is done in the forward model concerns the treatment of the multiple scattering. Only the single scattering term accounts on the actual atmospheric state, and it is apparent that this approximation is valid if the a priori state is sufficiently close to the true atmospheric state. Note that not only the forward model but also the Jacobian are affected by the multiple scattering approximation. The regularization method which is used in the inversion process is the Tikhonov regularization with an a priori regularization parameter. This means that the regularization parameter, which should balance the residual and the constraint, is chosen in advance and is not correlated with the true measurement. The a priori selection of the regularization parameter is performed for synthetic data, and therefore the method can be problematic especially when the measurement is affected by large systematic errors. The scientific processor developed at the German Aerospace Center is the counterpart of the offline processor, which is not, however, limited by any time constraints. This brings the opportunity to employ more time-consuming approaches and study their impact. The processor uses the Picard iteration method to simulate the radiance field in a full spherical atmosphere and includes polarization as well as Ring effects. A large class of regularization methods as for instance, the Tikhonov regularization, the iteratively regularized Gauss-Newton method, the regularizing Levenberg-Marquardt method, the asymptotical regularization approach and the regularized total least-squares method can be used for a specific application. Here a comparison between limb retrieval results obtained by the operational and the scientific processor for the SCIAMACHY instrument is presented.

Since the foundation of the SCIAMACHY Quality Working Group (SQWG) in a joint ESA-DLR-NIVR inter-agency effort in late 2006, the ESA operational Level 2 processor was significantly improved w.r.t. data quality and product range. During the last two years the product list was substantially enhanced by new (total columns of SO2, BrO, OClO, H2O, CO, Limb BrO profiles, Limb cloud flags) and improved products (total columns of O3, NO2, Absorbing Aerosol Index, Limb O3 profiles, Limb NO2 profiles). For example, important improvements were achieved in the O3 and NO2 profile calculation by implementing an upgraded retrieval scheme and using now Level 1b version 7.0 data with an improved pointing correction. Nadir products of total column O3 and Absorbing Aerosol Index were improved by applying a radiometric degradation correction (m-factors) in the Level 1 to 2 processing step.

In this poster we present a comparison between limb retrieval results obtained by using the operational and a scientific processor for the SCIAMACHY instrument. The scientific processor uses as forward model, a Picard iteration model, and as inversion model, direct and iterative regularization methods. By contrast, the operational processor uses an approximate forward model with multiple scattering correction and the Tikhonov regularization with a constant value of the regularization parameter.

A general mathematical description, mostly in terms of graph theory, is given for reactions of organic chemistry. The corresponding computer program generates all products that can result from a given set of starting materials interacting according to a given set of reaction schemes. Example reactions from combinatorial chemistry, synthetic organic chemistry, and mass spectroscopic structure elucidation are considered in detail.

Two important tasks in computer-aided structure elucidation (CASE) are the generation of candidate structures from a given molecular formula, and the ranking of structure candidates according to compatibility with an experimental spectrum. Candidate ranking with respect to electron impact mass spectra is based on virtual fragmentation of a candidate structure and comparison of the fragments’ isotope distributions against the spectrum of the unknown compound, whence a structure–spectrum compatibility matchvalue is computed. Of special interest is the matchvalue’s ability to distinguish between the correct and false constitutional isomers. Therefore a quality score was computed in the following way: For a (randomly selected) spectrum–structure pair from the NIST MS library all constitutional isomers are generated using the structure generator MOLGEN. For each isomer the matchvalue with respect to the library spectrum is calculated, and isomers are ranked according to their matchvalues. The quality of the ranking can be quantified in terms of the correct structure’s relative ranking position (RRP). This procedure was repeated for 100 randomly selected spectrum–structure pairs belonging to small organic compounds. In this first approach the RRP of the correct isomer was 0.27 on average.