Textured Dust Storm Activity in NE Amazonis-SW Arcadia, Mars: Phenomenology and Dynamical Interpretation

Dust storms are Mars's most notable meteorological phenomenon, but many aspects of their structure and dynamics remain mysterious. The cloud-top appearance of dust storms in visible imagery varies on a continuum between diffuse/hazy and textured. Textured storms contain cellular structure and/or banding, which is thought to indicate active lifting within the storm. Some textured dust storms may contain the deep convection that generates the detached dust layers observed high in Mars's atmosphere. This study focuses on textured, local dust storms in a limited area within NE Amazonis and SW Arcadia Planitiae (25°-40° N,155°-165° W) using collocated observations by instruments on board the Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) satellites. In northern fall and winter, this area frequently experiences dust storms with a previously unreported ruffled texture that resembles wide, mixed-layer rolls in the Earth's atmosphere, a resemblance that is supported by high resolution active sounding and passive radiometry in both the near and thermal infrared. These storms are mostly confined within the atmospheric boundary layer and are rarely sources of detached dust layers. The climatology and structure of these storms is thus consistent with an underlying driver of cold air advection events related to the passage of strong baroclinic waves. While the properties of the studied region may be ideal for detecting these structures and processes, the dynamics here are likely relevant to dust storm activity elsewhere on Mars.