CLIMERS - GNSS-T Setup

CLIMERS - GNSS-T Setup

The Research Group for Climate and Environmental Remote Sensing (CLIMERS) at TU Wien uses earth observation technology to conduct research in the field of earth science.

It uses satellite remote sensing technology to create long-term data sets of various Earth system variables. The focus is on the observation of soil moisture and vegetation.

The signals emitted by GNSS satellites are in the microwave frequency range - similar to the signals from scientific remote sensing satellites that observe vegetation from space. These remote sensing satellites provide information on the vegetation optical depth (VOD). The VOD describes the extent to which electromagnetic radiation is attenuated by vegetation. This attenuation depends, among other things, on the density of leaves, branches and the water content of the vegetation. The VOD is an important model parameter in climate research. It is used to analyze changes in vegetation structure, drought and water content and is essential for climate models and the monitoring of forest ecosystems.

 

GNSS-T Setup

The GNSS-T Setup (GNSS Transmissometry) uses GNSS signals to study the interaction between vegetation and microwave radiation. The aim is to record VOD in more detail and to better understand it in the long term. Two stations are used for this purpose:

  • Reference station: On the Heubergturm with a clear view of the sky.
  • Measuring station: At the DRAIN site, under the canopy, where the GNSS signals are transmitted through the vegetation.

GNSS signals of various satellite systems are continuously recorded at both locations. The recorded data is analyzed to evaluate the signal attenuation as a function of satellite positions and orbits. Both temporal changes and spatial effects caused by the tree canopy are made visible.

 

Supporting Camera System

In addition, two vertically aligned cameras monitor the canopy of the DRAIN site from below. They provide optical images of the tree structure, which are combined with the GNSS data to enable a complete analysis of the vegetation.