WAAS and the Ionosphere – A Historical Perspective: Monitoring Storms

Abstract

Satellites belonging to the Global Navigation Satellite System (GNSS) emit radio signals that are used routinely to determine position. Over the past two decades, satellite-based augmentation systems (SBAS) have been developed to render GNSS position estimates safe and reliable for aircraft navigation. As a radio signal propagates through the ionosphere, it experiences delay due to the presence of charged particles along the signal ray path. Disturbances of the ionosphere can cause this delay to increase dramatically. Indeed, the ionosphere currently remains the largest source of positioning error for single-frequency GNSS users. From a GNSS perspective, the threat to positioning accuracy posed by an ionospheric disturbance depends upon its magnitude. This paper examines how the Wide Area Augmentation System (WAAS), the augmentation of the United States'

Space Plasma Physics: A Review

“…The unpredictable additional signal delay caused by increased ionospheric densities can lead to 10 s of meters of positioning error when user receivers acquire only a single-GPS frequency, as is currently the case for civil aircraft navigation. For this reason, GPS-based navigation is denied when large ionospheric storms are detected by the system used to augment GPS for aircraft [596]. Although ionospheric storms have been studied for decades [597], [598], extreme space weather events that could cause unusually large and rapid ionospheric variations resulting from dayside E × B uplift to remain a concern [263].…”

Space Weather: From solar origins to risks and hazards evolving in time

“…Any sudden and localized changes that are not reflected in the model or in the VTEC measurements will cause errors for users of single frequency receivers. An example of a system that currently supports singlefrequency user receivers is the US GPS-based Wide Area Augmentation System (WAAS), designed to assist civil aviation users (Sparks et al, 2022). This type of Space Weather hazard has potential to decrease in the future, when users are able to use dual-frequency receivers more widely, with the advent of a GPS constellation that transmits a second frequency.…”

Statistical Characteristics of Total Electron Content Intensifications on Global Ionospheric Maps

“…These enhancement and depletion structures are found to be driven and modulated by one or multiple factors including the solar irradiance, solar wind and magnetospheric conditions, geomagnetic field, neutral wind, and lower atmospheric forcing. The dynamically‐changing electron density enhancements and depletions can significantly alter radio signals transmitting through the ionosphere, impacting space‐borne navigation and communication (Hernandez‐Pajares et al., 2011; Sparks et al., 2021).…”

“…density enhancements and depletions can significantly alter radio signals transmitting through the ionosphere, impacting space-borne navigation and communication (Hernandez-Pajares et al, 2011;Sparks et al, 2021).…”