2025ApJ...989..171K

We present medium-wave (∼0.5-13 μm) radiative flux distributions and spectra derived from high-resolution atmospheric dynamics simulations of an exoplanet, WASP-121 b. This planet serves to illustrate several important features. Assuming different chemical compositions for its atmosphere (e.g., H₂/He only and Z ∈ {1, 12} times solar metallicity), the outgoing radiative flux is computed using full radiative transfer that folds in the James Webb Space Telescope (JWST) and Ariel instrument characteristics. We find that the observed variability depends strongly on the assumed chemistry and the instrument wavelength range, hence the probed altitude of the atmosphere. With H₂/He only, the flux and variability originate near the 10⁵ Pa level; with solar and higher metallicity, the ∼10³ Pa level is probed, and the variability is distinguishably reduced. Our calculations show that JWST and Ariel have the sensitivity to capture the atmospheric variability of exoplanets like WASP-121 b, depending on the metallicity-both in repeated eclipse and phase-curve observations.