Spatial and temporal characterization of SCIAMACHY limb pointing errors during the first three years of the mission C. von Savigny1, J. W. Kaiser2, H. Bovensmann1, J. P. Burrows1, I. S. McDermid3, and T. Leblanc3 1Institute of Environmental Physics (IUP/IFE), University of Bremen, Otto-Hahn-Allee 1, 28334 Bremen, Germany 2Remote Sensing Laboratories, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland 3Jet Propulsion Laboratory, California Institute of Technology, Table Mountain Facility, Wrightwood, CA 92397–0367, USA
Abstract. Limb scattering retrievals of atmospheric minor constituent
profiles require highly accurate knowledge of the tangent heights
during the measurements. The limb scattering measurements of the
Scanning Imaging Absorption spectroMeter for Atmospheric
CartograpHY (SCIAMACHY) on Envisat are affected by tangent height
errors of up to 2 km. This contribution provides a summary of the
temporal and spatial variation of the SCIAMACHY limb pointing
errors during the first three years of the SCIAMACHY mission. The
tangent height errors are retrieved from the limb measurements in
the UV-B spectral range. A seasonal modulation of the monthly mean
tangent height offsets is identified with amplitudes of 800m (220m)
before (after) the improvement of the Envisat orbit propagator
model in December 2003. Even after the December 2003 orbit model
improvement a constant offset component of about 1km is present.
Furthermore, pointing discontinuities are identified that coincide
with the daily updates of the on-board orbit propagator model. In
order to reduce the errors in ozone profile retrievals caused by
pointing errors to less than 5%, the tangent heights have to be
known to within 250m.
Citation: von Savigny, C., Kaiser, J. W., Bovensmann, H., Burrows, J. P., McDermid, I. S., and Leblanc, T.: Spatial and temporal characterization of SCIAMACHY limb pointing errors during the first three years of the mission, Atmos. Chem. Phys., 5, 2593-2602, doi:10.5194/acp-5-2593-2005, 2005.