  We estimate spatial gradients in the ionosphere using the Global Positioning
System (GPS) and GLONASS (Russian global navigation system) observations,
utilising data from multiple GPS stations in the vicinity of Murchison
Radio-astronomy Observatory (MRO). In previous work the ionosphere was
characterised using a single-station to model the ionosphere as a single layer
of fixed height and this was compared with ionospheric data derived from radio
astronomy observations obtained from the Murchison Widefield Array (MWA).
Having made improvements to our data quality (via cycle slip detection and
repair) and incorporating data from the GLONASS system, we now present a
multi-station approach. These two developments significantly improve our
modelling of the ionosphere. We also explore the effects of a variable-height
model. We conclude that modelling the small-scale features in the ionosphere
that have been observed with the MWA will require a much denser network of
Global Navigation Satellite System (GNSS) stations than is currently available
at the MRO.
