  Robust atmospheric and radiative transfer modeling will be required to
properly interpret reflected light and thermal emission spectra of terrestrial
exoplanets. This will help break observational degeneracies between the
numerous atmospheric, planetary, and stellar factors that drive planetary
climate. Here we simulate the climates of Earth-like worlds around the Sun with
increasingly slow rotation periods, from Earth-like to fully Sun-synchronous,
using the ROCKE-3D general circulation model. We then provide these results as
input to the Spectral Planet Model (SPM), which employs the SMART radiative
transfer model to simulate the spectra of a planet as it would be observed from
a future space-based telescope. We find that the primary observable effects of
slowing planetary rotation rate are the altered cloud distributions, altitudes,
and opacities which subsequently drive many changes to the spectra by altering
the absorption band depths of biologically-relevant gas species (e.g., H2O, O2,
and O3). We also identify a potentially diagnostic feature of synchronously
rotating worlds in mid-infrared H2O absorption/emission lines.
