Video of ionospheric scintillation

Recently, we ran a small article on ionospheric scintillation and how dramatically it can change depending on atmospheric conditions. A few days later we showed two more interesting plots, both to the same scale, which demonstrated how substantial the different ionospheric scintillation conditions can be.

However, there is nothing quite like a video to really show how the scintillation can affect the signal. So today, we have just that!

What we did was make all-sky images for each of the two extremes shown in that last post we made on the topic.

The observing frequency was the same in both cases 58.594 MHz), 1 second integration per frame, 195.3 kHz bandwidth. The sequence is sped up somewhat (5 minutes data in about 30 seconds of video). As the time of day was the same in both instances, so the radio sky is in roughly the same orientation.

On the 25.12.2013 (left), the ionosphere exhibited extreme scintillation. The two bright sources (Cas A and Cyg A) are flickering quite dramatically. However, exactly two days later (27.12.2013, right), the ionosphere was relatively stable and the brightnesses of the two strong radio sources remain steady.

Ionospheric Scintillation with KAIRA and LOFAR

Yesterday we had a seminar from one of our visiting scientists. The subject was ionospheric scintillation and the speaker was Richard Fallows from ASTRON, Netherlands. The abstract of the presentation was:

 The wide bandwidth of KAIRA (Kilpisjärvi Atmospheric Imaging Receiver Array) and LOFAR (Low Frequency Array) is opening up new perspectives in the study of ionospheric scintillation. Direct observing at station level has enabled observations which combine low-band and high-band modes to cover the full available frequency bandwidth from 10 to 250 MHz. For the first time, the evolution of scintillation from weak to strong scattering regimes has been directly observed in dynamic spectra. "Scintillation arcs", seen previously in two-dimensional power spectra from interstellar scintillation observations, have been noted for the first time using observations of ionospheric scintillation. This offers new methods of studying the plasma structures giving rise to the scintillation.

It was an excellent talk... really interesting, great results and a lively discussion afterwards. Thanks Richard!

Thomas Ulich (standing) introduces the speaker
Richard Fallows (right). Photo: E. Turunen.

That also prompted us to investigate some of the riometry data that we had taken and look at some of the scintillation effects that we see in that. It was certainly good to examine some of the data with an expert at hand to advise us on what we were seeing.

A Night of Northern Lights

Last night the Northern Lights appeared early above Sodankylä. The western horizon wasn't even completely dark yet. Here is a short time-lapse film spanning of this fantastic night of observations with the All-Sky Camera of the Sodankylä Geophysical Observatory (SGO), Sodankylä, Finland.

The film covers the night of 1st/2nd March 2013.

The all-sky camera uses a fish-eye lens with 180° field of view pointing vertically up. It takes grey-scale images through filters of green, blue and red. The green image is taken every 20 seconds, the red and blue images are taken once per minute. These images are then overlaid to make an RGB (false-)colour image. The blue and red images are recycled to cover those green frames, for which there's no red or blue data. This sometimes results in blue lights being out of place. But this is a small price to pay for the overall colour effect.

Enjoy!