On the icy edge at Louth and Korolev craters

The modern climate of Mars has been well characterized from over a decade of orbiting spacecraft, in situ measurements via landers/rovers, and theoretical advances in climate modeling. Nonetheless, important questions remain unanswered, including the present-day mass balance of the north polar residual cap and its icy outliers. Exposed water-ice mounds are found in craters, and extend as far equatorward as 70.2°N. Due to their southerly location, these ice mounds are likely more sensitive to ongoing changes in climate. We analyze high-resolution images of the Louth crater ice mound, and employ a coupled 1-D thermal and atmospheric model to estimate annual mass balance of both Louth and Korolev water ice. We incorporate the effects of shallowly-sloping surfaces and seasonally-dependent water ice albedo. No clear trend in the advance or retreat of Louth crater water ice is observed in over 4 Mars years of repeat, high-resolution images. Secular changes are either sufficiently small as to not be detected, or the ice is in equilibrium. Modeled mass balance ranges from −6 to +2 mm of water ice per Mars year at both sites, with nominal cases being in near-equilibrium (<0.5 mm of ice loss per Mars year).