22-EPN3-073: Emergence of Ice Ripples by Sublimation at Various Wind Velocities and Air Pressure
Visit by Sabrina Carpy of the Laboratoire de Planétologie et Géosciences (France) and Philippe Claudin of the Laboratoire de Physique et Mécanique des Milieux Hétérogènes (France), to TA2.4 Planetary Environment Facilities (PEF), AU (Denmark)
Dates of visit: 04-08 March 2024
Report summary: Sublimation waves are the result of the sublimation of icy substrates under turbulent winds. They are expected to be found on many planetary surfaces with volatile ices in contact with an atmosphere. They are periodic, linear and transverse bedforms of different scales (centimeter to decameter) depending on their dry windy environment [Bordiec et al, 2020]. Apart from the BIA’s [Weller, 1969; Mellor and Swithinbank, 1989; Bintanja et al, 2001] and on the walls of ice caves [Curl, 1966], very few field measurements have been collected on sublimation waves. There is no extensive morphological and kinetic data of the development of these bedforms and there are no systematic measurements of the bedform’s wavelength change when continuously varying the wind velocity and fluid viscosity. This is why we have performed a series of experiments in the AWTS-II on carbon dioxide ice under a dry air atmosphere.
After initial difficulties with the ice slab creation and surface conditions, we managed to track the evolution of the substrate height throughout the sublimation phase using laser profilometry. We observed emergent morphologies that could be traces of the linear instability, but whether they correspond to the expected sublimation waves remains to be confirmed by detailed data analysis. Also, an unforeseen phenomenon was observed where transverse waves of frost on leading edges of the ice slab would migrate downstream as the aerodynamic forces on the growing frost would break off flakes. We are developing a model to link this frost coverage to the local friction velocity distribution.
