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Your
query was:
an="C21A-1056"
HR: 0800h
AN: C21A-1056
TI: Hyperspectral
Analysis of Dust Concentration, Snow Grain Size, and Broadband Albedo of
Alpine Snowcover
AU: * Cassidy, M P
EM: cassidym@nsidc.org
AF: National Snow & Ice Data Center,
Cooperative Institute for Research in Environmental Sciences, 216 UCB
University of Colorado, Boulder, CO 80309 United States
AU: Painter, T H
EM: tpainter@nsidc.org
AF: National Snow & Ice Data Center,
Cooperative Institute for Research in Environmental Sciences, 216 UCB
University of Colorado, Boulder, CO 80309 United States
AB: Springtime desert dust storms regularly deposit
radiatively absorbing dust upon the San Juan Mountains of southwestern
Colorado. The dust deposits reduce the albedo of snow in visible wavelengths,
accelerate grain metamorphism, and increase grain size. Because the dust increases
net visible absorption and increases grain size, likewise increasing
near-infrared and shortwave infrared absorption, the radiative effects of
desert dust should have significant impacts upon the energy balance of the
seasonal snowpack in the San Juan Mountains. The NASA/JPL Airborne
Visible/Infrared Imaging Spectrometer (AVIRIS) is of sufficient spectral
resolution to quantitatively detect the radiative effects of dust upon the
grain size and visible albedo of snow. AVIRIS detects upwelling radiance in
224 contiguous spectral channels within the wavelength range of 400-2500
nanometers, and is flown at ~4 km altitude in a Twin Otter aircraft. We
analyze AVIRIS data collected over two energy balance monitoring sites in the
alpine and subalpine of Red Mountain Pass in the San Juan Mountains of
Colorado. These data were collected on May 19 and May 21 of 2004. We used the
software Atmospheric Correction Now (ACORN) to atmospherically correct the
AVIRIS data to apparent surface reflectance and enhanced the reflectance
retrieval with field spectra of a within scene calibration site. The
normalized differential dust in snow index (NDDSI) signifies relative dust
concentration by quantifying the slope of a dust absorption feature in the
spectral reflectance of snow. An inversion technique based on the
quantitative relationship between the area of an ice absorption feature at 1.03
m and its optically equivalent snow grain size is used to derive the spatial
distribution of snow grain radii. The relationship between quantitative
estimates of relative dust concentration and grain size is direct up to a
threshold dust concentration at which the relationship becomes inverse. The
absorption by large concentrations of dust appears to contaminate the scaled
area of the 1.03 m ice absorption feature.
DE: 0700 CRYOSPHERE (4540)
DE: 0712 Cryosol
DE: 0736 Snow (1827, 1863)
DE: 0758 Remote sensing
DE: 0764 Energy balance
SC: Cryosphere [C]
MN: Fall Meeting 2005
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