engleski

Klobuchar GPS Ionospheric Delay Model Perfomance During Quiet Space Weather in Northern Adriatic

The ionospheric delay is the major single source of GNSS positioning error. The complexity of causes, especially those related to space weather development and local ionospheric behaviour, makes the modelling of the GNSS ionospheric delay a very challenging task. In an attempt to at least partially tackle the problem of satellite signal ionospheric delay, a global model of GPS ionospheric delay (also known as Klobuchar model) has been introduced within the GPS service. Being a compromise between computational complexity and requested performance, Klobuchar model has been claimed to correct up to 70% of the GPS ionospheric delay, with the best results achieved in periods of quiet space weather. Here we present the results of Klobuchar model performance analysis during periods of quiet space weather in northern Adriatic. The geographical area has been chosen because of economic importance (dense air, maritime and road transport ; tourism ; large GPS user community). The aim of research has been to validate the performance of Klobuchar model in real conditions, and identify patterns of local dynamics of GPS ionospheric delay in order to explore them for development of the local GPS ionospheric model. Archived GPS ionospheric delay time series, observed at the site in northern Adriatic, were compared with time series generated by Klobuchar model utilising the broadcast Klobuchar model coefficients. After simple subtraction, the residual GPS ionospheric delay time series were statistically analysed in order to identify patterns of local ionospheric dynamics. Patterns leading to non-Klobuchar-like behaviour of the day-time GPS ionospheric delay sets were identified in summer, while more Klobuchar-like ionospheric dynamics was identified in winter. In general, Klobuchar model was accounted for a rather large systematic error, ranging from 0.1 m – 1.5 m. Research will be continued with the focus on further analysis of real GPS ionospheric delay dynamics, with the aim to produce a local quiet space weather GPS ionospheric model for northern Adriatic.

Klobuchar model; ionospheric delay

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