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1. Ice scallops: a laboratory investigation of the ice–water interface

   https://doi.org/10.1017/jfm.2019.398  

   Bushuk, Mitchell; Holland, David M.; Stanton, Timothy P.; Stern, Alon; Gray, Callum (August 2019, Journal of Fluid Mechanics)

   Ice scallops are a small-scale (5–20 cm) quasi-periodic ripple pattern that occurs at the ice–water interface. Previous work has suggested that scallops form due to a self-reinforcing interaction between an evolving ice-surface geometry, an adjacent turbulent flow field and the resulting differential melt rates that occur along the interface. In this study, we perform a series of laboratory experiments in a refrigerated flume to quantitatively investigate the mechanisms of scallop formation and evolution in high resolution. Using particle image velocimetry, we probe an evolving ice–water boundary layer at sub-millimetre scales and 15 Hz frequency. Our data reveal three distinct regimes of ice–water interface evolution: a transition from flat to scalloped ice; an equilibrium scallop geometry; and an adjusting scallop interface. We find that scalloped-ice geometry produces a clear modification to the ice–water boundary layer, characterized by a time-mean recirculating eddy feature that forms in the scallop trough. Our primary finding is that scallops form due to a self-reinforcing feedback between the ice-interface geometry and shear production of turbulent kinetic energy in the flow interior. The length of this shear production zone is therefore hypothesized to set the scallop wavelength. 

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2. The end of ice I

   https://doi.org/10.1073/pnas.1914254116  

   Moberg, Daniel R.; Becker, Daniel; Dierking, Christoph W.; Zurheide, Florian; Bandow, Bernhard; Buck, Udo; Hudait, Arpa; Molinero, Valeria; Paesani, Francesco; Zeuch, Thomas (November 2019, Proceedings of the National Academy of Sciences)

   The appearance of ice I in the smallest possible clusters and the nature of its phase coexistence with liquid water could not thus far be unraveled. The experimental and theoretical infrared spectroscopic and free-energy results of this work show the emergence of the characteristic hydrogen-bonding pattern of ice I in clusters containing only around 90 water molecules. The onset of crystallization is accompanied by an increase of surface oscillator intensity with decreasing surface-to-volume ratio, a spectral indicator of nanoscale crystallinity of water. In the size range from 90 to 150 water molecules, we observe mixtures of largely crystalline and purely amorphous clusters. Our analysis suggests that the liquid–ice I transition in clusters loses its sharp 1st-order character at the end of the crystalline-size regime and occurs over a range of temperatures through heterophasic oscillations in time, a process without analog in bulk water. 

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3. The Ecology of River Ice

   https://doi.org/10.1029/2021JG006275  

   Thellman, Audrey; Jankowski, Kathi Jo; Hayden, Brian; Yang, Xiao; Dolan, Wayana; Smits, Adrianne P.; O'Sullivan, Antóin M. (September 2021, Journal of Geophysical Research: Biogeosciences)

   null (Ed.)
4. Formation of sea ice ponds from ice-shelf runoff, adjacent to the McMurdo Ice Shelf, Antarctica

   https://doi.org/10.1017/aog.2020.9  

   Macdonald, Grant J.; Popović, Predrag; Mayer, David P. (September 2020, Annals of Glaciology)

   null (Ed.)

   Abstract Ponds that form on sea ice can cause it to thin or break-up, which can promote calving from an adjacent ice shelf. Studies of sea ice ponds have predominantly focused on Arctic ponds formed by in situ melting/ponding. Our study documents another mechanism for the formation of sea ice ponds. Using Landsat 8 and Sentinel-2 images from the 2015–16 to 2018–19 austral summers, we analyze the evolution of sea ice ponds that form adjacent to the McMurdo Ice Shelf, Antarctica. We find that each summer, meltwater flows from the ice shelf onto the sea ice and forms large (up to 9 km 2 ) ponds. These ponds decrease the sea ice's albedo, thinning it. We suggest the added mass of runoff causes the ice to flex, potentially promoting sea-ice instability by the ice-shelf front. As surface melting on ice shelves increases, we suggest that ice-shelf surface hydrology will have a greater effect on sea-ice stability. 

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5. Recrystallization of ice enhances the creep and vulnerability to fracture of ice shelves

   https://doi.org/10.1016/j.epsl.2021.117219  

   Ranganathan, Meghana; Minchew, Brent; Meyer, Colin R.; Peč, Matěj (December 2021, Earth and Planetary Science Letters)