https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:40513 Wed 13 Jul 2022 15:09:51 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:14006 Wed 11 Apr 2018 16:47:31 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:16961 Wed 11 Apr 2018 15:50:05 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3260 Wed 11 Apr 2018 15:36:10 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:17236 2 = 10¹⁴ , is demonstrated. Furthermore, the algorithm generates the spheroidal functions for complex order m . The coefficients of the differential equation can be simply modified so that the algorithm may solve any second order differential equation in Sturm–Liouville form. The prolate spheroidal functions and the spectral concentration problem in relation to band-limited and time-limited signals is discussed. We review the properties of these eigenfunctions in the context of Sturm–Liouville theory and the implications for a finite difference algorithm. A number of new suggestions for data fitting using prolate spheroidal wave functions with a heuristic for optimally choosing the value of c and the number of basis functions are described.]]> Wed 11 Apr 2018 15:20:21 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:392 Wed 11 Apr 2018 15:05:58 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19512 5% contribution from protons, identified by Lyman-alpha intensity, were excluded from the analysis. The Birkeland currents were derived with a spatial resolution of 3° in latitude and 2 h in local time. For southward interplanetary magnetic field (IMF), the electron precipitation occurred primarily within and near large-scale upward currents. The correspondence was less evident for northward IMF, presumably because the spatial variability is large compared to the areas of interest so that the number of events identified is smaller and the derived statistical distributions are less reliable. At dusk, the correlation between upward current and precipitation was especially high, where a larger fraction of the electron precipitation is accelerated downward by a field-aligned potential difference. Unaccelerated electron precipitation dominated in the morning sector, presumably induced by scattering of eastward-drifting energetic electrons into the loss cone through interaction with whistler-mode waves (diffuse precipitation) rather than by field-aligned acceleration. In the upward Region 1 on the dayside, where the electron precipitation is almost exclusively due to field-aligned acceleration, a quadratic relationship between current density and electron energy flux was observed, implying a linear current-voltage relationship in this region. Current density and electron energy flux in the regions of the large-scale upward currents from pre-midnight through dawn to noon are essentially uncorrelated, consistent with diffuse electron precipitation dominating the incident energy flux.]]> Wed 11 Apr 2018 14:53:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1993 Wed 11 Apr 2018 14:32:07 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28938 Wed 11 Apr 2018 13:28:49 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:305 Wed 11 Apr 2018 12:54:14 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:418 Wed 11 Apr 2018 12:41:32 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:29656 Wed 11 Apr 2018 11:45:46 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:4836 Wed 11 Apr 2018 11:44:59 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1994 Wed 11 Apr 2018 09:52:52 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28883 Wed 11 Apr 2018 09:26:13 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:13518 Wed 11 Apr 2018 09:16:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:41432 Wed 03 Aug 2022 14:19:25 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:54349 20 nT/s) geomagnetic disturbances (GMDs, also denoted as MPEs—magnetic perturbation events)—impulsive nighttime disturbances with time scale ∼5–10 min, have sufficient amplitude to cause bursts of geomagnetically induced currents (GICs) that can damage technical infrastructure. In this study, we present occurrence statistics for extreme GMD events from five stations in the MACCS and AUTUMNX magnetometer arrays in Arctic Canada at magnetic latitudes ranging from 65° to 75°. We report all large (≥6 nT/s) and extreme GMDs from these stations from 2011 through 2022 to analyze variations of GMD activity over a full solar cycle and compare them to those found in three earlier studies. GMD activity between 2011 and 2022 did not closely follow the sunspot cycle, but instead was lowest during its rising phase and maximum (2011–2014) and highest during the early declining phase (2015–2017). Most of these GMDs, especially the most extreme, were associated with high-speed solar wind streams (Vsw >600 km/s) and steady solar wind pressure. All extreme GMDs occurred within 80 min after substorm onsets, but few within 5 min. Multistation data often revealed a poleward progression of GMDs, consistent with a tailward retreat of the magnetotail reconnection region. These observations indicate that extreme GIC hazard conditions can occur for a variety of solar wind drivers and geomagnetic conditions, not only for fast-coronal mass ejection driven storms.]]> Tue 20 Feb 2024 16:19:14 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:31496 I_Total, and the distribution of radial current density, Jr, for all models are compared with AMPERE results. While the total currents are well correlated, the quantitative agreement varies considerably. The J_r distributions reveal discrepancies between the models and observations related to the latitude distribution, morphologies, and lack of nightside current systems in the models. The results motivate enhancing the simulations first by increasing the simulation resolution and then by examining the relative merits of implementing more sophisticated ionospheric conductance models, including ionospheric outflows or other omitted physical processes. Some aspects of the system, including substorm timing and location, may remain challenging to simulate, implying a continuing need for real-time specification.]]> Sat 24 Mar 2018 08:43:39 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:15487 Sat 24 Mar 2018 08:21:27 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5942 Sat 24 Mar 2018 07:48:25 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:5931 Sat 24 Mar 2018 07:48:25 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:37022 Fri 05 Mar 2021 15:37:55 AEDT ]]>