סמינר בחוג למדעי כדור הארץ - סמינר PhD מיוחד

Title: On the use of VLF radio receivers to study the mesosphere-lower-thermosphere (MLT) and the lower ionosphere

Abstract:

The base of the upper atmosphere (at an altitude range of ~60-100 km) consists of the mesosphere-lower-thermosphere (MLT) and the lower ionosphere (the charged part of the atmosphere). Although this region is important for satellite orbits, radio wave communication and general circulation models, it is the least studied part of the atmosphere, as it is too high for weather-balloon measurements, and too low for in-situ measurements by satellites. Therefore, remote-sensing techniques are widely used, in order to study this region.

One of these remote-sensing techniques involves the use of very low frequency (VLF) electromagnetic radio waves. VLF signals are constantly generated by various natural and man-made sources, which can be detected using VLF antennas. Examination of the received signal properties allows the probing of the ionosphere and the MLT.  The findings of this study include a link between VLF signal amplitudes and mesopause temperatures, and the first observations of the semi-annual oscillation in the nighttime D-region. Finally, preliminary signatures of gravity waves detected in VLF measurements will be presented.

מארגנת הסמינר: ד"ר רוית חלד