Casey A. Moore, John E. Moores, Mark T. Lemmon, Scot C.R. Rafkin, Raymond Francis, Jorge Pla-Garcia, Robert M. Haberle, María-Paz Zorzano, Javier Martin-Torres, John R. Burton. 2016. A full martian year of line-of-sight extinction within Gale Crater, Mars as acquired by the MSL Navcam through sol 900. Icarus 264, 102-108, DOI: 10.1016/j.icarus.2015.09.001

We report on line-of-sight extinction in northern Gale Crater, Mars as seen by the Mars Science Laboratory (MSL) rover, Curiosity from sol 100 to sal 900; a little more than an entire martian year. Navcam images oriented due north, which show the distant crater rim, the near ground and the sky allow the extinction due to dust within the crater to be determined. This line-of sight extinction is compared to a complementary dataset of column extinctions derived from Mastcam. The line-of-sight extinction within the crater is less than the column extinction for the majority of the martian year. This implies that the relatively low mixing ratio of dust within the crater as compared to the atmosphere above the crater rim persists through most of the year. This suggests relatively little mixing between the atmosphere above the crater and the atmosphere inside the crater and suggests that northern Gale Crater is a net sink of dust in the current era. The data does however show a yearly convergence of the line-of-sight extinction and the column-averaged extinction around L-s = 270-290 degrees. This suggests that air above the crater mixes with air in the crater at this time, as predicted by mesoscale models. Matching line-of-sight and column extinction values are also seen around L-s approximate to 135 degrees, a season that has only been observed once in this dataset, this is particularly interesting as the Rover Environmental Monitoring Station onboard Curiosity reports increased convective boundary layer heights in the same season. (C) 2015 Elsevier Inc. All rights reserved.