Crystal growth of air hydrates over 720 ka in Dome Fuji (Antarctica) ice cores: microscopic observations of morphological changes below 2000 m depth.

The article describes the microscopic observations of the growth and morphological changes of air-hydrate crystals below 2,000 meter (m) depth within the ice core from Dome Fuji, Antarctica. Results reveal depth variations of number concentration and mean radius in Dome Fuji ice core. Crystals below 2,000m appeared either spherical or ellipsoidal. The researchers suggest possible reduction of the link between variations in geometric parameters and palaeoclimatic changes. Two possible mechanisms are considered for the changes in the distribution of air-hydrate crystals in the deep ice sheet, which are the coalescence process in which several crystals join together into one large crystal, and the Ostwald ripening process in which the larger crystals grow while the small crystals shrink.