The marked color difference between ice and snow clearly delineates the snowline just below the icefall in this photograph, which is from September 1998. The glacier mass balance at this time, estimated from the average elevation of the snowline (about 1800 m), was -0.37 m water equivalent. Subsequent melt and snowline recession resulted in a very negative mass balance (-1.11 m we) for Blue Glacier in 1998.
Haley Wight, from U. California (Santa Crux), recently examined the photos with the goal of orthorectifying the images with respect to a digital elevation model. Achieving this would reduce the errors in the methods that we have used so far, and might also open the possibility of feature tracking to calculate glacier flow velocities. She has identified several steps that are necessary in order to improve the image control, one being additional surveying of positions of landmarks that are visible in the photographs.