Science

Gabon’s Rain Forest in a Radar Trap for Researchers

How much biomass is in the forest? These determine German researchers in Gabon with a specialized radar equipment on aircraft. The data are used as a reference for a satellite ESA mission, then around the world intended the carbon bound in plants, important for the fight against climate change.With the German pair of twins satellite tandem-X radar technology measurement of the altitude differences on the Earth with unprecedented precision. Also, they provide information on surface properties, about land development, roads, fields and forests. They cannot however one: determine the biomass of forests. And that is important for the global carbon balance, which is in turn essential for climate change. Because the radar beams facing the twin satellites bombard the Earth are reflected by the treetops. How much the trees are means how much biomass they have.

Radar beams enter the height of the trees

That’s why have researchers of the German Center for Aeronautics and Space (DLR), which operates the tandem-X satellite. Developed a radar system, not only the existence of a forest track allows you to, but also the height of the trees. This in turn, the amount of biomass can be determined. Throughout February was the new system in use for test flights in the West Africa Gabon, located north and South of the Equator.

Plane Circulating Gabon's Rain Forest in a Radar Trap for Researchers
The twin-engine turbo prop machine DO 228-212 is suitable by their rectangular cabin and the large openings in the floor particularly well to the installation of specific camera and radar systems. Photo: DLR

A research aircraft of the DLR, a twin-engined Dornier DO 228-212, is equipped with special radar, which operates in several frequency bands. Some rays are as reflected that the tandem-X satellite at the tree tops, others penetrate to the ground, before they are thrown back. The height of the forest is calculated from the data obtained and created a vertical 3D-Profil. “On the basis of these parameters we can deduce how much carbon in the forest biomass is bound”, as Professor Irena Hajnsek, project manager of the mission referred to in AfriSAR. SAR stands for Synthetic Aperture Radar, as the radar technique.

Pilots must wear oxygen masks

The mission is a real challenge for pilots. You must fly at an altitude of 6000 m well, in which the brain is more reliably supplied with oxygen, additionally no pressurized cabin has plane (DO 228-212). “Wearing an oxygen mask is therefore mandatory,” says Oliver Brieger, head of the DLR research operations. In addition in Gabon highly changeable weather.

Gabon's Rain Forest Deflector
The reflector with its three perpendicular to one another standing area collects all the incident energy and sends back directly in the direction from which she came – analog to a cat’s eye in the visible range. Photo: DLR

There are often high enough cloud turbulence, heavy thunderstorms especially in the evening and haze with visibility. The radar beams penetrate though freely. If it is not however possible the pilots to keep the plane steady and to depart no more than two meters from the planned course measurement is unusable. Upon completion of the mission, a medical record, which is later the 3D model of the forest is formed the radar data of multiple parallel flight paths?

The results serve as reference data of the satellite mission planned by the European Space Agency ESA for 2020 biomass. Biomass is measured around the world the amount of biomass, as changes by destructions that cause storms and fires.