HR: 15:10h
AN: C33A-07    [Abstracts]
TI: Black Carbon Mass Concentration in California Mountain Snow
AU: * Hadley, O L
EM: ohadley@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0221, La Jolla, CA 92093, United States
AU: Corrigan, C
EM: ccorrigan@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0221, La Jolla, CA 92093, United States
AU: Kirchstetter, T W
EM: twkirchstetter@lbl.gov
AF: Lawrence Berkeley National Lab, 1 Cyclotron Rd, MS70-215, Berkeley, CA 94720, United States
AU: Cliff, S S
EM: sscliff@ucdavis.edu
AF: University of California, Davis, 105 Walker Hall, Davis, CA 95616, United States
AU: Ramanathan, V
EM: vram@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0221, La Jolla, CA 92093, United States
AB: Recent modeling studies have shown that deposition of black carbon (BC) to snow and ice lowers the albedo of snow and exerts a positive forcing on the climate. This effect is also a likely contributor to the observed ice and snow retreat in glaciers, ice sheets, and mountain snow pack. Observational data of actual BC concentrations in snow, which would help to constrain and validate these results, are scarce. This study presents the concentration of BC in fresh snow measured at two mountain locations in Northern California (Lassen Volcano Natl. Park and Donner Summit), as well as that in coastal rainfall at Trinidad Head, CA. These measurements are the first of this kind made in California. Average BC concentration at Lassen Natl. Park and Donner summit were respectively 6.8 and 9.7 ng per gram of snow. When placed in context with the modeled effect of BC on fresh snow albedo, these concentrations indicate a lowering of the snow albedo by 0.5 to 0.8%. As the snow pack ages, models predict that this effect will be increasingly amplified. Measurements of ambient aerosols during the rain events, as well as HySPLIT back-trajectories, provide additional information regarding possible sources of BC in California mountain snow packs. For the samples collected in this study, most of the soot in the snow appears to be of local origin. The average BC concentration in the coastal rain was 6.0 ng per gram of water, with the highest concentrations (12 ng/g) corresponding to the only back-trajectories clearly indicative of long-range trans-Pacific transport.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0736 Snow (1827, 1863)
DE: 1813 Eco-hydrology
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
SC: Cryosphere [C]
MN: 2007 Fall Meeting