  In an effort to estimate the largely unknown effects of photospheric
temperature fluctuations on spectroscopic abundance determinations, we have
studied the problem of LTE line formation in the inhomogeneous solar
photosphere based on detailed 2-dimensional radiation hydrodynamics simulations
of the convective surface layers of the Sun. By means of a strictly
differential 1D/2D comparison of the emergent equivalent widths, we have
derived "granulation abundance corrections" for individual lines, which have to
be applied to standard abundance determinations based on homogeneous 1D model
atmospheres in order to correct for the influence of the photospheric
temperature fluctuations. In general, we find a line strengthening in the
presence of temperature inhomogeneities as a consequence of the non-linear
temperature dependence of the line opacity. For many lines of practical
relevance, the magnitude of the abundance correction may be estimated from
interpolation in the tables and graphs provided with this paper. The
application of abundance corrections may often be an acceptable alternative to
a detailed fitting of individual line profiles based on hydrodynamical
simulations. The present study should be helpful in providing upper bounds for
possible errors of spectroscopic abundance analyses, and for identifying
spectral lines which are least sensitive to the influence of photospheric
temperature inhomogeneities.
