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2.5. SATELLITE GROUP 69
2.5 Satellite Group
Participating scientist Steffen Beirle, Tim Deutschmann, Barbara Dix, Ossama Ibrahim, Christian
Frankenberg, Michael Grzegorski, Klaus-Peter Heue, Jens Hollwedel, Muhammad Fahim Khokhar,
Sven Kühl, Thiery Marbach, Janis Pukite, Suniti Sanghavi, Thomas Wagner, and Walburga Wilms-
Grabe
Abstract The Satellitegroup is part of the researchgroup Atmospheric Physics of Prof. Dr. Ulrich
Platt. The satellite born remote sensing of the Earth’s atmosphere at the University of Heidelberg
started in 1996 with the retrieval of atmospheric trace gases, namely NO2 and BrO. Today a wide variety
of trace gases and other atmospheric parameters (Aerosols, Clouds, Radiative Transfer) from different
satellite instruments are investigated at the IUP (see also http://satellite.iup.uni-heidelberg.de).
Figure 2.34: Satellite measurement of the reflected and scattered sun light (yellow). The spectral
signatures of several atmospheric trace gases are analysed in selected spectral ranges using the DOAS
method. Displayed are the fitting results for various species analysed in the satellite group.
Overarching topic and Background For about 10 years now, a new generation of UV/vis/NIR
satellite instruments (GOME, SCIAMACHY, OMI) with moderate spectral resolution allows the
retrieval of a large variety of atmospheric trace gases. In particular, global maps of several tropospheric
trace gases like O3, BrO, NO2, CO, CH4, CO2, HCHO, SO2, H2O, O2, O4, and cloud properties can
be analysed from observations in nadir viewing mode. The most important advantage of such satellite
observations is their spatial (horizontal) coverage and resolution. The latest generation of nadir looking
UV/vis satellite instruments (e.g. OMI) achieves global coverage within one day and has a horizontal
resolution of about 13 x 24 km 2 . From such satellite observations, various individual sources like large
cities can be identified. In addition, the observation of scattered sun light in limb geometry allows to
retrieve vertical profiles of several stratospheric trace gases like O3, NO2, BrO and OClO.
Funding The group activities are funded through various national and international projects, e.g.
SCIAMACHY validation, FORMAT, STAR, Tropische Tropopause, NOXTRAM, EVERGREEN, AC-
CENT
Main methods From the measured spectra, the narowband absorption features of several trace
gases are analysed using the DOAS method (see Figure). The result of the spectral analysis represents
the trace gas absorption integrated along the absorption path. In addition, also the broad band
spectral features are analysed; they yield information in particular on the cloud cover, aerosol load and
ground albedo. Various algorithms for the analysis of satellite spectra were developed in the satellite
group within the last years. For the detailed interpretation of the analysed spectral information,
radiative transfer modelling is needed. A 3-D Monte-Carlo radiative transfer model (TRACY) was
developed in our group, which allows to simulate various complex viewing geometries and atmospheric
properties. The retrieved global data sets are further investigated using image sequence techniques.