A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances

Fallows, R., Forte, B., Astin, I., Allbrook, T., Arnold, A., Wood, A. ORCID: 0000-0002-7527-4757, Dorrian, G., Mevius, M., Rothkaehl, H., Matyjasiak, B., Krankowski, A., Anderson, J., Asgekar, A., Avruch, I.M., Bentum, M., Bisi, M.M., Butcher, H.R., Ciardi, B., Dabrowski, B., Damstra, S., de Gasperin, F., Duscha, S., Eislöffel, J., Franzen, T.M.O., Garrett, M.A., Grieβmeier, J., Gunst, A.W., Hoeft, M., Hörandel, J.R., Iacobelli, M., Intema, H.T., Koopmans, L.V.E., Maat, P., Mann, G., Nelles, A., Paas, H., Pandey, V.N., Reich, W., Rowlinson, A., Ruiter, M., Schwarz, D.J., Serylak, M., Shulevski, A., Smirnov, O.M., Soida, M., Steinmetz, M., Thoudam, S., Toribio, M.C., van Ardenne, A., van Bemmel, I.M., van der Wiel, M.H.D., van Haarlem, M.P., Vermeulen, R.C., Vocks, C., Wijers, R.A.M.J., Wucknitz, O., Zarka, P. and Zucca, P., 2020. A LOFAR observation of ionospheric scintillation from two simultaneous travelling ionospheric disturbances. Journal of Space Weather and Space Climate, 10: 10. ISSN 2115-7251

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Abstract

This paper presents the results from one of the first observations of ionospheric scintillation taken using the Low-Frequency Array (LOFAR). The observation was of the strong natural radio source Cassiopeia A, taken overnight on 18–19 August 2013, and exhibited moderately strong scattering effects in dynamic spectra of intensity received across an observing bandwidth of 10–80 MHz. Delay-Doppler spectra (the 2-D FFT of the dynamic spectrum) from the first hour of observation showed two discrete parabolic arcs, one with a steep curvature and the other shallow, which can be used to provide estimates of the distance to, and velocity of, the scattering plasma. A cross-correlation analysis of data received by the dense array of stations in the LOFAR “core” reveals two different velocities in the scintillation pattern: a primary velocity of ~20–40 ms−1 with a north-west to south-east direction, associated with the steep parabolic arc and a scattering altitude in the F-region or higher, and a secondary velocity of ~110 ms−1 with a north-east to south-west direction, associated with the shallow arc and a scattering altitude in the D-region. Geomagnetic activity was low in the mid-latitudes at the time, but a weak sub-storm at high latitudes reached its peak at the start of the observation. An analysis of Global Navigation Satellite Systems (GNSS) and ionosonde data from the time reveals a larger-scale travelling ionospheric disturbance (TID), possibly the result of the high-latitude activity, travelling in the north-west to south-east direction, and, simultaneously, a smaller-scale TID travelling in a north-east to south-west direction, which could be associated with atmospheric gravity wave activity. The LOFAR observation shows scattering from both TIDs, at different altitudes and propagating in different directions. To the best of our knowledge this is the first time that such a phenomenon has been reported.

Item Type: Journal article
Publication Title: Journal of Space Weather and Space Climate
Creators: Fallows, R., Forte, B., Astin, I., Allbrook, T., Arnold, A., Wood, A., Dorrian, G., Mevius, M., Rothkaehl, H., Matyjasiak, B., Krankowski, A., Anderson, J., Asgekar, A., Avruch, I.M., Bentum, M., Bisi, M.M., Butcher, H.R., Ciardi, B., Dabrowski, B., Damstra, S., de Gasperin, F., Duscha, S., Eislöffel, J., Franzen, T.M.O., Garrett, M.A., Grieβmeier, J., Gunst, A.W., Hoeft, M., Hörandel, J.R., Iacobelli, M., Intema, H.T., Koopmans, L.V.E., Maat, P., Mann, G., Nelles, A., Paas, H., Pandey, V.N., Reich, W., Rowlinson, A., Ruiter, M., Schwarz, D.J., Serylak, M., Shulevski, A., Smirnov, O.M., Soida, M., Steinmetz, M., Thoudam, S., Toribio, M.C., van Ardenne, A., van Bemmel, I.M., van der Wiel, M.H.D., van Haarlem, M.P., Vermeulen, R.C., Vocks, C., Wijers, R.A.M.J., Wucknitz, O., Zarka, P. and Zucca, P.
Publisher: EDP Sciences
Date: 20 March 2020
Volume: 10
ISSN: 2115-7251
Identifiers:
NumberType
10.1051/swsc/2020010DOI
1304379Other
Divisions: Schools > School of Science and Technology
Depositing User: Jonathan Gallacher
Date Added: 20 Mar 2020 15:01
Last Modified: 20 Mar 2020 15:01
URI: http://irep.ntu.ac.uk/id/eprint/39426

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