A conceptual model for explanation of Albedo changes in Martian craters

We propose a conceptual model to interpret AM/PM high albedo events (HAEs) in crater interiors at the Martian seasonal polar caps. This model consists of two components: (1) a relatively permanent high-albedo water-ice body exposed in a crater interior and (2) a variable crater albedo in response to aerosol optical depth, dust contamination, and H2O/CO2 frost deposits or sublimes in four phases, based on temperature and solar longitude changes. Two craters (Korolev crater of fully exposed water-ice layer and 'Louth' crater of partially exposed water-ice layer) are used to demonstrate the model. This model explains the HAEs and their seasonal changes and suggests that many crater-like features formed in the last episodic advance of the polar ice cap in the last high obliquity period should have water-ice exposed or covered. For the AM-only HAEs craters, there seems no need of a water-ice layer to be fully exposed, but a subsurface water-ice layer (or ice-rich regolith) is a necessary condition. (c) 2008 Elsevier Ltd. All rights reserved.