Caused by ionosphere’s strong impact on radio signal propagation, high resolution and highly accurate reconstructions
of the ionosphere’s electron density distribution are demanded for a large number of applications, e.g.
to contribute to the mitigation of ionospheric effects on Synthetic Aperture Radar (SAR) measurements. As a new
generation of remote sensing satellites the TanDEM-L radar mission is planned to improve the understanding and
modelling ability of global environmental processes and ecosystem change. TanDEM-L will operate in L-band
with a wavelength of approximately 24 cm enabling a stronger penetration capability compared to X-band (3
cm) or C-band (5 cm). But accompanied by the lower frequency of the TanDEM-L signals the influence of the
ionosphere will increase. In particular small scale irregularities of the ionosphere might lead to electron density
variations within the synthetic aperture length of the TanDEM-L satellite and in turn might result into blurring and
azimuth pixel shifts. Hence the quality of the radar image worsens if the ionospheric effects are not mitigated.
The Helmholtz Alliance project “Remote Sensing and Earth System Dynamics” (EDA) aims in the preparation
of the HGF centres and the science community for the utilisation and integration of the TanDEM-L
products into the study of the Earth’s system. One significant point thereby is to cope with the mentioned
ionospheric effects. Therefore different strategies towards achieving this objective are pursued: the mitigation of
the ionospheric effects based on the radar data itself, the mitigation based on external information like global Total
Electron Content (TEC) maps or reconstructions of the ionosphere and the combination of external information
and radar data.
In this presentation we describe the geostatistical approach chosen to analyse the behaviour of the ionosphere
and to provide a high resolution 3D electron density reconstruction. As first step the horizontal structure
of the ionosphere is studied in space and time on the base of ground-based TEC measurements in the European
region. In order to determine the correlation of measurements at different locations or points of time the TEC
measurements are subtracted by a base model to define a stationary random field. We outline the application of the
NeQuick model and the final IGS TEC maps as background and show first results regarding the distribution and
the stationarity of the resulting residuals. Moreover, the occurred problems and questions are discussed and finally
an outlook towards the next modelling steps is presented
