Description :
Release of gas (e.g. methane) at the lake bed can result in the formation of elongated bubbles in ice cover. The columnar ice cover pictured here includes a large number of bubbles that are about 1 mm in diameter and range in length from about 10 cm to 30 cm. Its total thickness was measured to be 114 cm. This type of ice displays in purplish tones in RADARSAT-2 multi-polarization image composites which indicates relatively high levels of backscatter in HH and VV. The associated backscatter mechanism remains a topic of discussion in literature. Similar to snow ice, this type of ice is likely to have a lower bearing
capacity than bubble-free columnar ice.
Photographe :
van der Sanden, J J
Collection :
Ressources naturelles Canada
Haute-résolution :
6.65 MB
4928x3264 pixels
300 ppi (jpeg)
Nota :
Depending on the weather conditions, ice cover can grow the full extent of the available water depth and become attached to the lake bottom. Unfortunately, bottom-fast ice cannot be discriminated from floating columnar ice in individual RADARSAT-2 multi-polarization composite images because both ice types display black. Discrimination of the two ice types is facilitated by a times series of RADARSAT-2. The measured backscatter level
decreases when the ice becomes bottom-fast and increases when the ice grows. Similar to shorelines, bottom-fast ice formations jeopardize the trafficability of ice roads because their presence increases the risk of traffic induced ice cover failures. However, the presence of bottom-fast ice is more difficult to ascertain.
Géographie :
6819; Tibbitt-to-Contwoyto Winter Road; Territoires du Nord-Ouest; 2020-351.JPG; Nunavut