An Improved Scanner Model for Sciamachy
R.C. Snel(1) and J.M. Krijger(1)
(1) SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands
An improved model of the SCIAMACHY scanner unit
is presented. The model is used for combination of the
on-ground ambient and thermal vacuum calibration
data, and removes errors initially introduced into the
calibration key data as a result of ambiguities in the
polarisation frame definitions used during on-ground
calibration and in 0-1 data processing.
The scanner model builds on the Fresnel equations and
describes limb, nadir and sun over ESM diffuser
geometries. It is possible to add up to two dielectric
layers with arbitrary thickness on any of the modeled
mirror or diffuser surfaces. On-ground and in-flight
measurements were used to verify the model output.
The possibility of modeling contamination of the mirror
and diffuser surfaces allows future investigation of
certain aspects of instrument degradation, such as scan
angle dependent degradation and UV transmission loss.