Characterization of a local dust storm on Mars with REMS/MSL measurements and MARCI/MRO images

Abstract

The REMS instrument on board the Curiosity rover has been collecting meteorological data from Gale crater on Mars since August 2012. A dust storm that developed north of Gale crater in sol 852 of the Mars Science Laboratory (MSL) mission spread above the location of the Curiosity rover during sols 853–855 (December 30, 2014 to January 1, 2015, areocentric solar longitude Ls 263°, MY32). The storm was observed by the MARCI imaging instrument on the Mars Reconnaissance Orbiter and its effects in the local meteorology were recorded in situ by the REMS instrument on MSL. Here we present a detailed report of the effects of the storm at Gale crater. Using MARCI images, we measured the size and altitude of the dust storm, which reached a size of 482,000 km2, attained an altitude of 19 km above the ground, and dispersed through the Gale crater and its surrounding area the next sol. The dispersion of the dust from the storm was roughly in agreement with the expected values of the winds on Ls 263° from climatological values in the Mars Climate Database (MCD). REMS data show that the storm produced the following effects when the dust arrived at Gale: (1) An increase in the daily amplitude of the atmospheric pressure variation (~15 ± 3 Pa) mainly through a reduction of the daily minimum pressure (~12 Pa) in the late afternoon hours. (2) A decrease of the UV signal (~30%). (3) An unexpected increase in the temperature of the air close to the surface (~14 ± 4 K) in the early afternoon (LT~14–15). (4) A cooling of the surface near noon (~6 ± 4.5 K). The warming of local air was contrary to previous observations of effects of dust storms on the Martian surface. This could be due to the vertical distribution of dust when the storm arrived at Gale crater, which was less vertically extended than in the previous sol. However, the data does not allow for a quantitative evaluation of this hypothesis. Although the storm could be observed from orbit only over one single sol above Gale crater its effects over the local meteorology lasted longer and dissipated in a time-scale of 3 sols.