  Using the atmospheric structure from a 3D global radiation-hydrodynamic
simulation of HD 189733b and the open-source BART code, we investigate the
difference between the secondary-eclipse temperature structure produced with a
3D simulation and the best-fit 1D retrieved model. Synthetic data are generated
by integrating the 3D models over the Spitzer, HST, and JWST bandpasses,
covering the wavelength range between 1 and 11 um. Using the data from
different observing instruments, we present detailed comparisons between the
temperature-pressure profiles recovered by BART and those from the 3D
simulations. We calculate several averages of the 3D thermal structure and
implement two temperature parameterizations to investigate different thermal
profile shapes. To assess which part of the thermal structure is best
constrained by the data, we generate contribution functions for both our
theoretical model and each of our retrieved models. Our conclusions are
strongly affected by the spectral resolution of the instruments included, their
wavelength coverage, and the number of data points combined. We also see some
limitations in each of the temperature parametrizations. The results show that
our 1D retrieval is recovering a temperature and pressure profile that most
closely matches the arithmetic average of the 3D thermal structure. When we use
a higher resolution, more data points, and a parametrized temperature profile
that allows more flexibility in the middle part of the atmosphere, we find a
better match between the retrieved temperature and pressure profile and the
arithmetic average.
