Statistical Correlation Analysis of Field‐Aligned Currents Measured by Swarm. Issue 10 (10th October 2018)

• Record Type: Journal Article
• Authors: Yang, J. ‐Y.; Dunlop, M. W.; Lühr, H.; Xiong, C.; Yang, Y.‐Y.; Cao, J. ‐B.; Wild, J. A.; Li, L.‐Y.; Ma, Y.‐D.; Liu, W.‐L.; Fu, H.‐S.; Lu, H.‐Y.; Waters, C.; Ritter, P.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 10(2018)
• Page Start: 8170
• Page End: 8184
• Publication Date: 2018-10-10
• Subjects: field‐aligned currents -- correlations -- Pi1B; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2018JA025205
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: We investigate the statistical, dual‐spacecraft correlations of field‐aligned current (FAC) signatures between two Swarm spacecraft. For the first time, we infer the orientations of the current sheets of FACs by directly using the maximum correlations obtained from sliding data segments. The current sheet orientations are shown to broadly follow the mean shape of the auroral boundary for the lower latitudes and that these are most well ordered on the dusk side. Orientations at higher latitudes are less well ordered. In addition, the maximum correlation coefficients are explored as a function of magnetic local time and in terms of either the time shift ( δt ) or the shift in longitude ( δlon ) between Swarms A and C for various filtering levels and choice of auroral region. We find that the low‐latitude FACs show the strongest correlations for a broad range of magnetic local time centered on dawn and dusk, with a higher correlation coefficient on the dusk side and lower correlations near noon and midnight. The positions of maximum correlation are sensitive to the level of low‐pass filter applied to the data, implying temporal influence in the data. This study clearly reflects the two different domains of FACs: small‐scale (some tens of kilometers), which are time variable, and large‐scale (>50 km), which are rather stationary. The methodology is deliberately chosen to highlight the locations of small‐scale influences that are generally variable in both time and space. We may fortuitously find a potential new way to recognize bursts of irregular pulsations (Pi1B) using low‐Earth orbit satellites. Key Points: For the first time, we infer the orientations of the current sheets of FACs using a maximum correlation method This study clearly reflects two different domains of FACs: small‐scale, which are time variable, and large‐scale, which are rather stationary We find a potential new way to recognize bursts of irregular pulsations (Pi1B) using low‐earth orbit satellites