  We use observations from the Compact Reconnaissance Imaging Spectrometer for
Mars (CRISM) of the north polar cap during late summer for two Martian years,
to monitor the complete summer cycle of albedo and water ice grain size in
order to place quantitative limits of the amount of water ice deposited in late
summer.
  We establish here for the first time the complete spring to summer cycle of
water ice grain sizes on the north polar cap. The apparent grain sizes grow
until Ls=132, when they appear to shrink again, until they are obscured at the
end of summer by the north polar hood.
  Under the assumption that the shrinking of grain sizes is due to the
deposition of find grained ice, we quantify the amount of water ice deposited
per Martian boreal summer, and estimate the amount of water ice that must be
transported equatorward.
  Interestingly, we find that the relative amount of water ice deposited in the
north cap during boreal summer (0.7-7 microns) is roughly equivalent to the
average amount of water ice deposited on the south polar cap during austral
summer (0.6-6 microns).
