Forstinventur im Fichtelgebirge mit dem Flugzeugradar: ein 3D Waldhöhenbild, das auf eine Höhenlinienkarte projiziert ist. Das Gebiet zeigt eine topographische Höhenvariation von 600 Meter und eine Waldhöhenvariation von 0 bis 30 Meter. Die Waldhöhen wurden mit der Technik der so genannten polarimetrischen SAR-Interferometrie bestimmt, die im DLR-Institut für Hochfrequenztechnik und Radarsysteme entwickelt worden ist. Diese Technik wird auch bei der INDREX-2-Flugkampagne in Indonesien über tropischem Regenwald erprobt werden.
Ein Radarbild, aufgenommen mit einem langen Frequenzband (L-Band) und der horizontal polarisierten, elektromagnetischen Welle – dem E-SAR System des DLR. Das Bild zeigt ein Waldgebiet. Erkennbar sind auch einige Waldstraßen und ein kleines Gehöft.
Oberpfaffenhofen - Scientists from the Institute of High Frequency Technology and Radar Systems (IHR) recently returned to Oberpfaffenhofen from a successful flight campaign in India. On behalf of the Indian Space Research Organization (ISRO), various types of landscape were recorded in high resolution using SAR (Synthetic Aperture Radar) in September and October 2004 in order to be able to determine environmentally relevant parameters from the data obtained. The E-SAR (Experimental Synthetic Radar) system developed by the IHR operates in four frequency ranges (X-, C-, L- and P-band radar, from 10 GHz to 400 MHz), enables day and night imaging and is independent of weather conditions.
This was the first time that DLR researchers had flown this airborne radar system in Asia. Preparing the campaign was not only a scientific challenge, but also a logistical one, which DLR's flight operations handled with routine and perfection. After all, the mobile laboratory weighs 2.5 tons, which would have led to extremely high fuel consumption on board the Do228 aircraft and would have necessitated several more stopovers. So the DLR aircraft flew with a small crew, and the radar system was transported separately to Ahmedabad by air freight. Once there, the DLR scientists quickly installed the radar in the aircraft, tested it in flight and calibrated it - at outside temperatures of between 30 and 40 degrees Celsius.
The actual measurement flights began (almost) on time on September 13. Over the next three weeks, the ground crew and aircraft crew were on the move in central India, surveying agricultural areas, coal seams and flooded areas. The radar images obtained are used to create terrain models and determine biomass, among other things, and are also intended to provide information for rice and grain cultivation.
Once the radar data has been processed and calibrated, a cooperation agreement between the Institute of High Frequency Technology and Radar Systems and ISRO/SAC (Space Applications Center) will be signed for joint data evaluation and analysis of the results. A stay of two guest scientists from Ahmedabad in Oberpfaffenhofen is planned for next year.
The campaign in India was followed by an ongoing campaign in Indonesia. In this, the DLR researchers are attempting to determine the biomass of the rainforest on a random basis and validate it with ground measurements. The experiment is intended to provide findings for a later space mission (we will also report on this in a future issue).
