Comparison of temporal fluctuations in the total electron conDtisecunsstions estimates from EISCAT and GPS along the same line of sight

The impact of space weather events on satellitebased
technologies (e.g. satellite navigation and precise positioning)
is typically quantified on the basis of the total electron
content (TEC) and temporal fluctuations associated with
it. GNSS (global navigation satellite systems) TEC measurements
are integrated over a long distance and thus may include
contributions from different regions of the ionised atmosphere
which may prevent the resolution of the mechanisms
ultimately responsible for given observations. The purpose
of the experiment presented here was to compare TEC
estimates from EISCAT and GPS measurements. The EISCAT
measurements were obtained along the same line of
sight of a given GPS satellite observed from Tromsø. The
present analyses focussed on the comparison of temporal
fluctuations in the TEC between aligned GPS and EISCAT
measurements. A reasonably good agreement was found between
temporal fluctuations in TEC observed by EISCAT
and those observed by a co-located GPS ionospheric monitor
along the same line of sight, indicating a contribution
from structures at E and F altitudes mainly to the total TEC
in the presence of ionisation enhancements possibly caused
by particle precipitation in the nighttime sector. The experiment
suggests the great potential in the measurements to be
performed by the future EISCAT 3D system, limited only in
the localised geographic region to be covered.