Progrss in measuring snow cover from ERTS imagery

A hybrid of digital and analog analysis techniques are being employed to determine the accuracy with which snow area and temporal change in snow area can be determined from ERTS satellite imagery. The principal analysis tool is an Electronic Satellite Image Analysis Console (ESIAC) which permits display of time-lapse sequences of color composite images on a color TV monitor. Binary snow maps are generated electronically, superimposed on the image display for any necessary human editing, them measured for area in a digital counter. Results are checked against high altitude aircraft photography.Bright snow is relatively easy to measure. Snow in shadow or illuminated at low incidence angles is harder to identify unambiguously. Several potential solutions for this problem and for the problem of snow-tree mixtures are being studied. A time-lapse movie showing a full year of ERTS imagery of a typical mountian snowfield will be shown.