SAR Meets Atmosphere

Short Description

Starting point / motivation

Satellite based radar systems (Synthetic Aperture Radar - SAR) are well known for all-day and all-weather capabilities. In contrast to optical sensors, which are strongly influenced by cloud coverage, radar signals are able to penetrate clouds, thus delivering information reliably independent from weather conditions.

However, in order to reach the earth’s surface, radar signals have to travel through the atmosphere twice. This causes multiple effects such as e.g. range delays and interferometric phase delays, which have to be considered when interpreting results based on radar data. Therefore, atmospheric correction is of crucial importance when processing radar signals.

Contents and goals

SAME-AT contributes to a better understanding of the interaction between radar signals and the atmosphere. Increasing research activities in recent years demonstrate that certain interrelationships are still not fully understood.

SAME-AT therefore improves the modelling of atmospheric correction by using error budgets on the used atmospheric parameters. This information is derived from forecast uncertainties from the prediction of numerical weather models. A novel atmospheric correction approach is developed and specifically tested in the complex topography of the Alps in Austria.


In order to achieve this main goal, the SAME-AT consortium aims to improve the quality of the reference data in Austria by establishing a corner reflector network. Numerical weather models provide valuable information for SAR/InSAR correction approaches. Vice versa, observed SAR/InSAR delays can serve as data sources for the determination of the initial state (data assimilation) of weather models. SAR/InSAR delays allow conclusions to be drawn about the tropospheric moisture content, which is extremely valuable information for weather models.

An important part of SAME-AT is therefore the investigation of the possible benefit of SAR/InSAR delays on the quality of numerical weather prediction systems. SAME-AT therefore allows an improvement in both disciplines (Satellite based radar systems and development of numerical weather models). The high temporal resolution (e.g. hourly) of current weather models offers great added value for radar applications.

The developed methods for the correction of atmospheric delays will be integrated into ongoing projects (e.g. SuLaMoSA) in order to assess the feasibility for various applications such as deformation monitoring.

Expected results

The free availability of the Sentinel-1 radar data opened up new perspectives for a multitude of different applications and also expands the spectrum of potential user groups. Users of SAR-based interferometry can significantly improve the accuracy of their applications with the corrections of SAME-AT or the open source correction software of SAME-AT.

This significantly increases the attractiveness of SAR-based technologies. Thus, SAME-AT contributes to an improvement in the scientific and public use of freely available radar satellite data (Sentinel-1).

Project Partners


ZAMG - Zentralanstalt für Meteorologie und Geodynamik

Project partner


Contact Address

ZAMG - Zentralanstalt für Meteorologie und Geodynamik
Dr. Michael Avian
Hohe Warte 38
A-1190 Vienna