There are far-reaching conceptual similarities between bi-static surface
georadar and post-stack, "zero-offset" seismic reflection data, which
is expressed in largely identical processing flows. One important
difference is, however, that standard deconvolution algorithms routinely
used to enhance the vertical resolution of seismic data are notoriously
problematic or even detrimental to the overall signal quality when
applied to surface georadar data. We have explored various options
for alleviating this problem and have tested them on a geologically
well-constrained surface georadar dataset. Standard stochastic and
direct deterministic deconvolution approaches proved to be largely
unsatisfactory. While least-squares-type deterministic deconvolution
showed some promise, the inherent uncertainties involved in estimating
the source wavelet introduced some artificial "ringiness". In contrast,
we found spectral balancing approaches to be effective, practical
and robust means for enhancing the vertical resolution of surface
georadar data, particularly, but not exclusively, in the uppermost
part of the georadar section, which is notoriously plagued by the
interference of the direct air- and groundwaves. For the data considered
in this study, it can be argued that band-limited spectral blueing
may provide somewhat better results than standard band-limited spectral
whitening, particularly in the uppermost part of the section affected
by the interference of the air- and groundwaves. Interestingly, this
finding is consistent with the fact that the amplitude spectrum resulting
from least-squares-type deterministic deconvolution is characterized
by a systematic enhancement of higher frequencies at the expense
of lower frequencies and hence is blue rather than white. It is also
consistent with increasing evidence that spectral "blueness" is a
seemingly universal, albeit enigmatic, property of the distribution
of reflection coefficients in the Earth. Our results therefore indicate
that spectral balancing techniques in general and spectral blueing
in particular represent simple, yet effective means of enhancing
the vertical resolution of surface georadar data and, in many cases,
could turn out to be a preferable alternative to standard deconvolution
approaches.