  The surface gravities of cool (Teff < 13,000 K) hydrogen-atmosphere DA white
dwarfs, determined from spectroscopic analyses, are found to be significantly
higher than the canonical value of log g ~ 8 expected for these stars. It was
recently concluded that a problem with the treatment of convective energy
transport within the framework of the mixing-length theory was the most
plausible explanation for this high-log g problem. We pursue the investigation
of this discrepancy by computing model spectra of cool convective white dwarfs
from a small sequence (11,300 K < Teff < 12,800 K) of 3D hydrodynamical model
atmospheres, which feature a sophisticated treatment of convection and
radiative transfer. Our approach is to proceed with a differential analysis
between 3D and standard 1D models. We find that the 3D spectra predict
significantly lower surface gravities, with corrections of the right amplitude
as a function of effective temperature to obtain values of log g ~ 8 on
average. We conclude that the surface gravity distribution of cool convective
DA white dwarfs is much closer to that of hotter radiative objects when using,
for the treatment of the convection, 3D models instead of the mixing-length
framework.
