  Understanding the total flux and polarization signals of Earth-like planets
and their spectral and temporal variability is essential for the future
characterization of such exoplanets. We provide computed total (F) and linearly
(Q and U) and circularly (V) polarized fluxes, and the degree of polarization P
of sunlight that is reflected by a model Earth, to be used for instrument
designs, optimizing observational strategies, and/or developing retrieval
algorithms. We modeled a realistic Earth-like planet using one year of daily
Earth-observation data: cloud parameters (distribution, optical thickness, top
pressure, and particle effective radius), and surface parameters (distribution,
surface type, and albedo). The Stokes vector of the disk-averaged reflected
sunlight was computed for phase angles alpha from 0 to 180 degrees, and for
wavelengths lambda from 350 to 865 nm. The total flux F is one order of
magnitude higher than the polarized flux Q, and Q is two and four orders of
magnitude higher than U and V, respectively. Without clouds, the peak-to-peak
daily variations due to the planetary rotation increase with increasing lambda
for F, Q, and P, while they decrease for U and V. Clouds modify but do not
completely suppress the variations that are due to rotating surface features.
With clouds, the variation in F increases with increasing lambda, while in Q,
it decreases with increasing lambda, except at the largest phase angles. In
earlier work, it was shown that with oceans, Q changes color from blue through
white to red. The alpha where the color changes increases with increasing cloud
coverage. Here, we show that this unique color change in Q also occurs when the
oceans are partly replaced by continents, with or without clouds. The degree of
polarization P shows a similar color change. Our computed fluxes and degree of
polarization will be made publicly available.
