PT  - JOURNAL ARTICLE
AU  - Hyeyeon Chang
AU  - Moonseok Yoon
AU  - Sam Pullen
AU  - Leonardo Marini-Pereira
AU  - Jiyun Lee
TI  - Ionospheric spatial decorrelation assessment for GBAS daytime operations in Brazil
AID  - 10.1002/navi.418
DP  - 2021 Jun 20
TA  - NAVIGATION: Journal of the Institute of Navigation
PG  - 391--404
VI  - 68
IP  - 2
4099  - https://navi.ion.org/content/68/2/391.short
4100  - https://navi.ion.org/content/68/2/391.full
SO  - NAVIGATION2021 Jun 20; 68
AB  - Extensive ionospheric studies were conducted to support the initial phase of system design approval for the existing SLS-4000 GBAS installed at Antonio Carlos Jobim International Airport (formerly Galeão International Airport) (GIG) in Rio de Janeiro, Brazil. This paper focuses on determining the broadcast value of the standard deviation of vertical ionospheric gradients (or 𝜎vig) that is required to bound ionospheric spatial gradients in Brazil under nominal conditions during daytime hours. The time-step method is useful for gaining sufficient samples at distances less than the physical separation distance of ground stations and was utilized to estimate ionospheric spatial gradients. A new method called “geometric similarity” was developed to estimate ionospheric temporal gradients and evaluate the temporal effect added to the bounding 𝜎vig values. As a result, a 𝜎vig of 13 mm/km, including a temporal gradient contribution of approximately 2 mm/km, is conservative enough to bound ionospheric spatial decorrelation for daytime GBAS operations in Brazil.