  The energy balance and climate of planets can be affected by the reflective
properties of their land, ocean, and frozen surfaces. Here we investigate the
effect of host star spectral energy distribution (SED) on the albedo of these
surfaces using a one-dimensional (1-D) energy balance model (EBM).
Incorporating spectra of M-, K-, G- and F-dwarf stars, we determined the effect
of varying fractional and latitudinal distribution of land and ocean surfaces
as a function of host star SED on the overall planetary albedo, climate, and
ice-albedo feedback response. While noting that the spatial distribution of
land masses on a given planet will have an effect on the overall planetary
energy balance, we find that terrestrial planets with higher average land/ocean
fractions are relatively cooler and have higher albedo regardless of star type.
For Earth-like planets orbiting M-dwarf stars the increased absorption of water
ice in the near-infrared (NIR), where M-dwarf stars emit much of their energy,
resulted in warmer global mean surface temperatures, ice lines at higher
latitudes, and increased climate stability as the ice-albedo feedback became
negative at high land fractions. Conversely, planets covered largely by ocean,
and especially those orbiting bright stars, had a considerably different energy
balance due to the contrast between the reflective land and the absorptive
ocean surface, which in turn resulted in warmer average surface temperatures
than land-covered planets and a stronger potential ice-albedo feedback. While
dependent on the properties of individual planetary systems, our results place
so constraints on a range of climate states of terrestrial exoplanets based on
albedo and incident flux.
