  Ultra high energy neutrinos ($E_\nu > 10^{16.5}$eV$)$ are efficiently
measured via radio signals following a neutrino interaction in ice. An antenna
placed $\mathcal{O}$(15 m) below the ice surface will measure two signals for
the vast majority of events (90% at $E_\nu$=$10^{18}$eV$)$: a direct pulse and
a second delayed pulse from a reflection off the ice surface. This allows for a
unique identification of neutrinos against backgrounds arriving from above.
Furthermore, the time delay between the direct and reflected signal (D'n'R)
correlates with the distance to the neutrino interaction vertex, a crucial
quantity to determine the neutrino energy. In a simulation study, we derive the
relation between time delay and distance and study the corresponding
experimental uncertainties in estimating neutrino energies. We find that the
resulting contribution to the energy resolution is well below the natural limit
set by the unknown inelasticity in the initial neutrino interaction. We present
an in-situ measurement that proves the experimental feasibility of this
technique. Continuous monitoring of the local snow accumulation in the vicinity
of the transmit and receive antennas using this technique provide a precision
of $\mathcal{O}$(1 mm) in surface elevation, which is much better than that
needed to apply the D'n'R technique to neutrinos.
