The German ISWI instruments SOFIE and GIFDS

Kurzfassung

SOFIE (SOlar Flares detected by Ionospheric Effects) is an educational venture established by the DLR_Project_Lab in Neustrelitz, Germany. Its objective is a robust ground-based detection of solar radiation bursts, i.e. solar flares, via measureable changes in the lower ionosphere. In order to accomplish this, continuous signals of powerful VLF Navy transmitters are received and stored. SOFIE offers a professional insight into topics of space weather, the ionosphere and the radio wave propagation. During the project interested students may construct the antenna on their own. Moreover, they are given the opportunity to assemble and operate the receiver following the provided construction kit and the included installation manual. The German Aerospace Center (DLR) offers the students professional support and guidance. The recorded VLF data is transferred over the Internet directly to a server in the DLR_Project_Lab. SOFIE was started as a German educational project, however, a collaboration with schools in other countries is intended and welcome. Currently, there are six active SOFIE receivers operating in Germany and additional four abroad. The Global Ionospheric Flare Detection System (GIFDS), operated by the German Aerospace Center (DLR), consists of a ground-based network of Perseus SDR (Software Defined Radio) receivers which provide concurrent measurements of VLF signal strength and phase at multiple frequency channels ranging from 10 kHz to 100 kHz. One of the main objectives of GIFDS is the immediate and continuous detection of solar flares affecting the bottomside ionosphere and consequently inducing sudden interferences of VLF signals. In general, these measurements are determined by solar irradiation and geophysical conditions. The influence of diurnal variations on VLF amplitudes can be corrected by applying time series analysis followed by detrending. The VLF data is regularly adjusted by various transformation techniques to ensure a stabilized output. Finally, the results are compared with the X-ray flux obtained from GOES satellites to validate the magnitude and shape of flares recorded by GIFDS. As solar events can only be detected during daytime, DLR has been installing a uniform array of receivers at selected locations around the globe. Measurements carried out at the dayside part of the Earth will be provided 24/7 in the near future.