Comparison of observed thermal spectra of WASP-19b with the modelled spectra calculated using PHOENIX (solid line) at different metallicities with an average dayside heat redistribution (f = 0.5). The corresponding temperature-pressure profile is shown in the inset image (the grey shaded region corresponds to the structure inversion). The observed thermal spectrum of WASP-19b presented in this paper is adopted from Anderson et al. (2010, 2013) (filled square and filled circles), Gibson et al. (2010) (filled upward triangle), Bean et al. (2013) (open circles), Burton et al. (2012) (open diamond), and Lendl et al. (2013) (filled downward triangles). The emission features at 4.5 μm are due to CO in the presence of thermal inversion.