CrackMaps

=Crack Maps and surface roughness= As we have seen in the field, the ice in the Allan Hills has a lot of cracks that can influence the albedo. We used an upside-down triwall-box with a camera-hole in the top to try and make 10 photos of these cracks at each location (Figure 3(a)). The 10 photos are random: the randomization process involves a person turning around its own axis 3 times, walking 5 steps and throwing a glove in the air. The photo was then taken next to the glove with a standard orientation with respect to the sun and the process was repeated (eg. Figure 3(b)). 1 photograph was also taken under the albedo measurement. The hole for the camera was closer to the actual direction of the sun, so the upper side of the image always points to the sun.





Surface roughness
 The surface of the ice has different roughness at different sites. Using a flat board over the ice surface and photographing it from the side (Figure 4) we can estimate the relative roughness between different sites.



The intensity of reflection of the ice is different in the three primary channels on a color ccd. And a trough-light image under the box is almost completely void of red.

=Stereology to estimate crack area per volume= I used stereology to estimate crack area per volume of ice. The area ranges from 3.6 m 2 /m 3 in firn to 55.8 m 2 /m 3 in blue ice. The results are in.