Contact Information:

Stephen G. Warren
Department of Atmospheric Sciences
University of Washington, Box 351640
Seattle WA 98195 USA
tel: 206-543-7230 fax: 206-543-0308
e-mail: sgw@uw.edu

Thomas C. Grenfell
Department of Atmospheric Sciences
University of Washington, Box 351640
Seattle WA 98195 USA
tel: 206-543-9411 fax: 206-543-0308
email: tcg@atmos.washington.edu

Antony D. Clarke
Department of Oceanography
Universtiy of Hawaii at Manoa
1000 Pope Road
Marine Sciences Building
Honolulu, HI 96822
tel: 808-956-6215 fax: 808-956-7112
email: tclarke@soest.hawaii.edu

Dates:
Begin Date: 2006-08-02 00:00:00.0
End Date: 2006-08-10 00:00:00.0
Minimum Latitude: 79.90000
Maximum Latitude: 79.93300
Minimum Longitude: -24.50000
Maximum Longitude: -24.01700

Summary: Ice types, albedos and impurity content are characterized for the ablation zone of the Greenland ice sheet in Kronprinz Christians Land (808 N, 248 W). Along this ice margin the width of the ablation zone is only about 8 km. The emergence and melting of old ice in the ablation zone creates a surface layer of dust that was originally deposited with snowfall high on the ice sheet. This debris cover is augmented by locally derived wind-blown sediment. Subsequently, the surface dust particles often aggregate together to form centimetre-scale clumps that melt into the ice, creating cryoconite holes. The debris in the cryoconite holes becomes hidden from sunlight, raising the area-averaged albedo relative to surfaces with uniform debris cover. Spectral and broadband albedos were obtained for snow, ice hummocks, debris-covered ice, cryoconite-studded ice and barren tundra surfaces. Broadband ice albedos varied from 0.2 (for ice with heavy loading of uniform debris) to 0.6 (for ice hummocks with cryoconite holes). The cryoconite material itself has albedo 0.1 when wet.