Mooney, Michaela K.; (2022) A statistical analysis of the auroral boundaries; their response to geomagnetic dynamics and their use in auroral forecast verification. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text MKMooney_16107753_FinalCorrectedThesis.pdf - Accepted Version Download (18MB) | Preview

Abstract

The aurora and associated current systems are hazardous to space and ground-based infrastructure. In this thesis, the auroral boundaries determined from satellite images have been used to evaluate the performance of an operational auroral forecast model and explore the location and dynamics of the auroral boundaries in the context of the wider magnetosphere. The performance of the OVATION-Prime 2013 auroral forecast model is compared against the observed auroral boundaries. The analysis shows that the model performs well at predicting the location of the auroral oval, however the performance is reduced during periods of higher geomagnetic activity and in the high latitude nightside auroral oval. The model also underpredicts the probabilities of aurora occurring. The results of this analysis provide a benchmark against which future generations of auroral forecast models can be assessed. The lower model performance in the high latitude nightside sectors is likely due to substorm activity and so the statistical motion of the poleward auroral boundary and open-closed field line boundary (OCB) during substorms is analysed. The results show that the OCB does not contract uniformly after substorm onset. In sectors closest to the onset sector, the OCB contracts immediately while in sectors further from onset the OCB contracts later, distorting the shape of the OCB. However, the total nightside flux content of the polar cap decreases immediately at onset, in contrast to recent studies. Finally, the alignment between the equatorward auroral boundary and the plasmapause is explored. The statistical locations of the equatorward auroral boundary and the ionospheric projection of the plasmapause are compared. The two boundaries are found to be statistically offset in all sectors by 4 – 11°, suggesting that the equatorward auroral boundary does not map to the plasmapause. However, the separation between the two boundaries decreases with increasing levels of geomagnetic activity.

Download activity - last month

Export as JSONCSVXML

Download activity - last 12 months

Export as XMLCSVJSON

Downloads by country - last 12 months

Export as XMLJSONCSV

Archive Staff Only

View Item