HR: 0800h
AN: C21A-1057    [Abstracts]
TI: Measurements of Snow Sublimation Under Laboratory-Controlled Conditions
AU: * Neumann, T
EM: thomas.neumann@uvm.edu
AF: Univ. of Vermont, Geology Department 210 Delehanty Hall, Burlington, VT 05405 United States
AU: Perron, F
EM: Frank.E.Perron@erdc.usace.army.mil
AF: Department of Army Cold Regions Research and Engineering Lab, 72 Lyme Rd., Hanover, NH 03755 United States
AU: Albert, M
EM: Mary.R.Albert@erdc.usace.army.mil
AF: Department of Army Cold Regions Research and Engineering Lab, 72 Lyme Rd., Hanover, NH 03755 United States
AB: Snow sublimation is a fundamental process that plays an important role in interpreting ice core signals of climate change, ice sheet mass balance, remote sensing signatures over snow-covered terrain, and snow hydrology. Prior studies of snow sublimation have inferred the sublimation rate from energy, isotopic, or mass balance calculations using field data. Consequently, these studies were unable to control many of the environmental parameters which determine sublimation rate (e.g. temperature, relative humidity, snow microstructure). We present initial sublimation rate measurements on snow samples in the cold laboratory, where we are simultaneously controlling many of these parameters. Our approach is to introduce air of a specified temperature and relative humidity to a snow sample at a specified temperature. We vary the contact (residence) time between the air and snow sample by adjusting the air flow rate. Measurements of the snow sample temperature and the relative humidity of the air leaving the sample allow us to infer the sublimation rate. We repeat these measurements systematically with several different combinations of snow temperature and air flow rate. Results of experiments done to date show that the air stream exiting the snow sample is saturated under a wide range of sample temperature and air flow rate. This suggests that we have not yet measured the maximum possible sublimation rate at a given temperature. We expect that the measured sublimation rate will also be a function of grain size and the microstructure of the snow sample. To date, we have only used aged, well-rounded grains from sieved snow samples. In ongoing work, we plan to use natural snow samples from firn cores representing several different depositional environments. Finally, we compare our preliminary measurements with published data from field-based studies and model calculations.
DE: 0724 Ice cores (4932)
DE: 0736 Snow (1827, 1863)
DE: 0762 Mass balance (1218, 1223)
DE: 0766 Thermodynamics (1011, 3611, 8411)
DE: 0776 Glaciology (1621, 1827, 1863)
SC: Cryosphere [C]
MN: Fall Meeting 2005