  Coronal mass ejections (CMEs) are a manifestation of the Sun's eruptive
nature. They can have a great impact on Earth, but also on human activity in
space and on the ground. Therefore, modelling their evolution as they propagate
through interplanetary space is essential. EUropean Heliospheric FORecasting
Information Asset (EUHFORIA) is a data-driven, physics-based model, tracing the
evolution of CMEs through background solar wind conditions. It employs a
spheromak flux rope, which provides it with the advantage of reconstructing the
internal magnetic field configuration of CMEs. This is something that is not
included in the simpler cone CME model used so far for space weather
forecasting. This work aims at assessing the spheromak CME model included in
EUHFORIA. We employed the spheromak CME model to reconstruct a well observed
CME and compare model output to in situ observations. We focus on an eruption
from 6 January 2013 encountered by two radially aligned spacecraft, Venus
Express and STEREO-A. We first analysed the observed properties of the source
of this CME eruption and we extracted the CME properties as it lifted off from
the Sun. Using this information, we set up EUHFORIA runs to model the event.
The model predicts arrival times from half to a full day ahead of the in situ
observed ones, but within errors established from similar studies. In the
modelling domain, the CME appears to be propagating primarily southward, which
is in accordance with white-light images of the CME eruption close to the Sun.
In order to get the observed magnetic field topology, we aimed at selecting a
spheromak rotation angle for which the axis of symmetry of the spheromak is
perpendicular to the direction of the polarity inversion line (PIL). The
modelled magnetic field profiles, their amplitude, arrival times, and sheath
region length are all affected by the choice of radius of the modelled
spheromak.
