  Aims. To create a retrieval framework which encapsulates the 3D nature of
exoplanet atmospheres, and to apply it to observed emission phase curve and
transmission spectra of hot Jupiter exoplanet WASP-43b. Methods. We present our
3D framework, which is freely available as a stand-alone module from GitHub. We
use the atmospheric modelling and Bayesian retrieval package ARCiS (ARtful
modelling Code for exoplanet Science) to perform 8 3D retrievals on
simultaneous transmission (HST/WFC3) and phase-dependent emission (HST/WFC3,
Spitzer/IRAC) observations of WASP-43b as a case study. We assess how input
assumptions affect our retrieval outcomes. In particular we look at
constraining equilibrium chemistry vs a free molecular retrieval, the case of
no clouds vs parametrised clouds, and using Spitzer phase data that have been
reduced from two different literature sources. For the free chemistry
retrievals, we retrieve abundances of H2O, CH4, CO, CO2, AlO, and NH3 as a
function of phase, with many more species considered for the equilibrium
chemistry retrievals. Results. We find consistent super-solar C/O (0.6-0.9) and
super-solar metallicities (1.7-2.9 dex) for all retrieval setups that assume
equilibrium chemistry. Atmospheric heat distribution, hotspot shift (15.6 vs
4.5 for different Spitzer datasets), and temperature structure are influenced
by the Spitzer emission phase data. Comparisons are made with other studies of
WASP-43b, including available GCM simulations. Conclusions. The parametrised 3D
setup we have developed provides a valuable tool to analyse extensive
observational datasets such as spectroscopic phase curves. Near-future
observations with missions such as the James Webb Space Telescope (JWST) and
Ariel will greatly improve our understanding of the atmospheres of exoplanets
such as WASP-43b.
