Recurring Ionospheric Gradients, Irregularities, and Depletions Over New Zealand

Jeremy Ovadia and Eric Altshuler, Sean MacCallum and Pat Reddan, Dave Collett

Peer Reviewed

Abstract:	The Southern Positioning Augmentation Network (SouthPAN) will provide single frequency L1 Satellite-Based Augmentation Service (SBAS) to Australia and New Zealand, whose governments sponsor the enterprise. SouthPAN’s L1 service will use measurements from multiple GNSS constellations, including Global Positioning Service (GPS) and Galileo satellites, for a wide sampling of the ionosphere over a wide area of the Southern Pacific that covers part of the Indian Ocean and Tasman Sea. Both Geoscience Australia (GA) and Land Information New Zealand (LINZ) have collected global navigation satellite system (GNSS) observables since the 1990s utilizing their reference network of GNSS receivers, providing a vast amount of measurements to study ionospheric behavior over the SouthPAN service region. However, little existing research has studied ionospheric disturbances and irregularities that remain largely uncharacterized over the SouthPAN coverage area. To provide insight into the challenges SouthPAN's single frequency L1 service will face in mitigating ionospheric threats, GA and LINZ observables will be used to profile pronounced irregular patterns in ionospheric disturbances over New Zealand that appear during geomagnetic storms. Notably, storms on 31-March 2001, 08-November 2004, 11-May 2024, and 11-October 2024 are studied to observe recurring traveling gradients, widespread plasma depletions, and narrow spatial irregularities over the New Zealand ionosphere. Dual-shell spatiotemporal modeling highlights three-dimensional plasma dynamics during the storms and commonality of irregular disturbance patterns. Preliminary tests of SouthPAN’s L1 SBAS “local” storm detection algorithm on historical proxy system data during the four storms of interest suggests the ability to mitigate “local” ionospheric threats, as described in this paper, over New Zealand with minimal effects to SouthPAN availability.
Published in:	Proceedings of the 2026 International Technical Meeting of The Institute of Navigation January 26 - 29, 2026 Hyatt Regency Orange County Anaheim, California
Pages:	210 - 224
Cite this article:	Ovadia, Jeremy, Altshuler, Eric, MacCallum, Sean, Reddan, Pat, Collett, Dave, "Recurring Ionospheric Gradients, Irregularities, and Depletions Over New Zealand," Proceedings of the 2026 International Technical Meeting of The Institute of Navigation, Anaheim, California, January 2026, pp. 210-224. https://doi.org/10.33012/2026.20539
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