In Situ Observations of Ionospheric Heating Effects: First Results from a Joint SURA and NorSat‐1 Experiment

This work presents the first results of measurements of artificial plasma disturbance characteristics using the low‐orbit NorSat‐1 satellite, which are excited when the ionospheric F2 layer is modified by powerful high‐frequency (HF) waves emitted by the SURA heating facility. NorSat‐1 carries the multineedle Langmuir probe instrument, which is capable of sampling the electron density at a nominal rate up to 1 kHz. The uniqueness of this experiment lies in the fact that the satellite passes very close to the center of the HF‐perturbed magnetic flux tube and in situ observations are first carried out in winter when the absorption is still small in the morning as the Sun is low above the horizon. There are HF‐induced plasma temperature and density variations at satellite altitudes of about 580 km. Plasma irregularities are detected by in situ measurements down to 200 m at the southern border of the SURA heating region. Plain Language Summary The current stage in the development of active experiments includes the use of satellites for sensing plasma disturbances in situ. However, these data can only be obtained if the satellite crosses an HF‐perturbed magnetic flux tube, which rests on a region with highly developed turbulence generated near pump wave reflected altitude; in other words, “the satellite has to be in the right place at the right time.” This study presents results related to features of artificial plasma density irregularities at a height of 580 km obtained during the SURA‐NorSat‐1 active experiment when NorSat‐1 passed very close to the center of the HF‐perturbed magnetic flux tube. For the first time, in situ measurements were carried out by the satellite with such a high resolution of Langmuir probes in comparison with previous experiments with DEMETER and DMSP. It is shown that there are HF‐induced plasma temperature and density variations at satellite altitudes and an increase in temperature is more substantial than changes in plasma density. Plasma irregularities are detected by in situ measurements down to 200 m at the southern border of the SURA heating region. The spatial distribution of artificial plasma disturbances is strongly influenced by the “magnetic zenith” effect. Key Points Results of the first SURA‐NorSat‐1 joint experiment are presented Increase in temperature is more substantial than changes in plasma density in high‐frequency heating region In situ observations detect plasma irregularities down to 200 m at the southern edge