Bulletin of Glaciological Research, 2002, 19, 63-70
Surface albedo and characteristics of cryoconite (biogenic surface dust) on an Alaska glacier, Gulkana Glacier in the Alaska Range
Frontier Observational Research System for Global Change, International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Dr. P.O.Box 757335 Fairbanks AK 99775-7335 U.S.A.
Surface albedo and characteristics of cryoconite (surface dust on glaciers) were investigated on the Gulkana Glacier in the Alaska Range, U.S.A. The surface albedo ranged from 0.11 to 0.52 (mean: 0.32) in the ice area (below the snow line) and from 0.70 to 0.86 (mean: 0.71) in the snow area (above the snow line). The amount of cryoconite on the glacier surface ranged from 1.0 to 102 g m-2 (mean: 23 g m-2) in the ice area and from 0.8 to 1.7 g m-2 (mean: 1.2 g m-2) in the snow area. The proportion of organic matter in the cryoconite was higher in the snow area (10.2 to 22.1%, mean: 15.5%) than in the ice area (2.4 to 11.0%, mean: 7.1%). Microscopy of the cryoconite revealed that cryoconite on the ice area consisted of mineral particles, snow algae, and dark colored organic matter. The results show that the surface albedo in the ice area was reduced approximately 0.13 by cryoconite. The large amount of snow algae and organic matter in the cryoconite suggests that biological activity takes part in the albedo reduction. In the snow area, spetral albedo of the surface and microscopy of the cryoconite suggest that the surface albedo was significantly reduced by red snow algae (Chlamydomonas nivalis). The results were compared with those of a Himalayan glacier.