  We investigate a CME propagating towards Earth on 29 March 2011. This event
is specifically chosen for its predominately northward directed magnetic field,
so that the influence from the momentum flux onto Earth can be isolated. We
focus our study on understanding how a small Earth-directed segment propagates.
Mass images are created from the white-light cameras onboard STEREO which are
also converted into mass height-time maps (mass J-maps). The mass tracks on
these J-maps correspond to the sheath region between the CME and its associated
shock front as detected by in situ measurements at L1. A time-series of mass
measurements from the STEREO COR-2A instrument are made along the Earth
propagation direction. Qualitatively, this mass time-series shows a remarkable
resemblance to the L1 in situ density series. The in situ measurements are used
as inputs into a 3D magnetospheric space weather simulation from CCMC. These
simulations display a sudden compression of the magnetosphere from the large
momentum flux at the leading edge of the CME and predictions are made for the
time-derivative of the magnetic field (dB/dt) on the ground. The predicted
dB/dt were then compared with observations from specific equatorially-located
ground stations and show notable similarity. This study of the momentum of a
CME from the Sun down to its influence on magnetic ground stations on Earth is
presented as preliminary proof of concept, such that future attempts may try to
use remote sensing to create density and velocity time-series as inputs to
magnetospheric simulations.
