Wolfgang Balzer

The terraSAR-X satellite project

The objective of TerraSAR-X is the setup of an operational space borne X-Band SAR system in order to produce remote sensing products for commercial and scientific use. The TerraSAR-X project is conducted under the aegis of the DLR Space Flight Management and comprises a space and a ground segment. The space segment is designed and built by ASTRIUM GmbH, the ground segment is set up by several institutions of DLR, namely the German Remote Sensing Data Center, the Remote Sensing Technology Institute, the German Space Operations Center and the Microwaves and Radar Institute.

GOME level 1-to-2 data processor version 3.0: a major upgrade of the GOME/ERS-2 total ozone retrieval algorithm

The global ozone monitoring experiment (GOME) was launched in April 1995, and the GOME data processor (GDP) retrieval algorithm has processed operational total ozone amounts since July 1995. GDP level 1-to-2 is based on the two-step differential optical absorption spectroscopy (DOAS) approach, involving slant column fitting followed by air mass factor (AMF) conversions to vertical column amounts. We present a major upgrade of this algorithm to version 3.0. GDP 3.0 was implemented in July 2002, and the 9-year GOME data record from July 1995 to December 2004 has been processed using this algorithm. The key component in GDP 3.0 is an iterative approach to AMF calculation, in which AMFs and corresponding vertical column densities are adjusted to reflect the true ozone distribution as represented by the fitted DOAS effective slant column. A neural network ensemble is used to optimize the fast and accurate parametrization of AMFs. We describe results of a recent validation exercise for the operational version of the total ozone algorithm; in particular, seasonal and meridian errors are reduced by a factor of 2. On a global basis, GDP 3.0 ozone total column results lie between -2% and +4% of ground-based values for moderate solar zenith angles lower than 70 degrees. A larger variability of about +5% and -8% is observed for higher solar zenith angles up to 90 degrees.

SCIAMACHY near real time products and algorithms

SCIAMACHY, which is part of the ENVISAT-1 scientific payload, is a double grating spectrometer designed to observe the light reflected, transmitted and back-scattered by the Earths atmosphere. Its broad spectral coverage (240 to 2400 nm) combined with multiple viewing geometries (nadir, limb, solar and lunar occultation) enable the measurement of numerous atmospheric constituents in the stratosphere as well as in the troposphere. The list of trace gases includes O/sub 3/, NO/sub 2/, BrO, SO/sub 2/, OClO, H/sub 2/CO in the UV and visible regions and H/sub 2/O, N/sub 2/O, CO, CH/sub 4/ and CO/sub 2/ in the IR regions. Geolocated engineering calibrated products (level 1b) as well as geolocated geophysical products (level 2) containing the total column amounts for the above species (excluding CO/sub 2/) are produced by a near real time (NRT) processor and are available to users three hours after data acquisition. An enhanced off-line processor additionally produces (several days after acquisition) stratospheric profiles of most of the above molecules as well as O/sub 3/ profiles down to the troposphere. As an Expert Support Laboratory, the DLR-DFD in Oberpfaffenhofen has specified the algorithms required for the NRT processing chain. This paper summarises these NRT algorithms and the resulting level 1b and 2 products distributed to users.