  We use laboratory experiments and theoretical modeling to investigate the
surface expression of a subglacial discharge plume, as occurs at many fjords
around Greenland. The experiments consider a fountain that is released
vertically into a homogeneous fluid, adjacent either to a vertical or a sloping
wall, that then spreads horizontally at the free surface before sinking back to
the bottom. We present a model that separates the fountain into two separate
regions: a vertical fountain and a horizontal, negatively buoyant jet. The
model is compared to laboratory experiments that are conducted over a range of
volume fluxes, density differences, and ambient fluid depths. It is shown that
the non-dimensionalised length, width, and aspect ratio of the surface
expression are dependent on the Froude number, calculated at the start of the
negatively buoyant jet. The model is applied to observations of the surface
expression from a Greenland subglacial discharge plume. In the case where the
discharge plume reaches the surface with negative buoyancy the model can be
used to estimate the discharge properties at the base of the glacier.
