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Dust particles that absorb solar radiation in the atmosphere:
Iron oxide minerals (hematite or goethite)
Carbonaceous matter -- “black carbon”
What dust particles absorb heat from the sun to promote snow melt?
Are these particles found in snow ?
What’s in the dust?
Improving models ofsnow melt
(radiative transfer models)
Dust particles that absorb solar radiation and greatly accelerate snow melt:
Absorption of solar energy
from Reflectance measures
Fe oxide amountfrom magnetic measures
Organic matterfrom organic C %
Black carbon?
correlation?
correlation?
Average Reflectance
0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60
HIR
M (
Am
2 k
g-1
)
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
Reflectance vs.organic matter
Reflectance vs.Fe oxide amount
Reflectance
Fe
oxi
de
amo
un
t
0.15 0.20 0.25 0.30 0.350
1
2
3
4
5
Reflectance
C o
rg (
%)
For each sample:
Reflectance Spectroscopy for determining radiative properties & Fe oxide minerals of dust samples
Spectroscopy – study of objects based on the spectrum of color of light they emit or absorb
Bi-directional method – fixed angles for incoming halogen light and for reflected light (fiber optic pick-up). Measurements converted to “absolute reflectance” by removing absorption of white reference
HIR
M (
Am
2 kg
-1)
Reflectance Visible avg.
0.1 0.2 0.3 0.4 0.5 0.60.0000
0.0002
0.0004
0.0006
0.0008Sevier Lake
Lower Red PineUpper Red PineUpper Mill BLower Mill BBlind HollowSOLA2009 DOSMFF BSNE
MFF soil
SOLA
soil
BSNE
playa
dust-on-snow
Hem
atit
e +
Go
eth
ite
Fe oxides
~ 90 samples from Milford Flat
20%
Carbonaceous particles in Wasatch DOS
Aggregate of carbon particles
Carbon particle
Cu + Zn5 μm 2 μm
SEM analysis by George Breit
0.15 0.20 0.25 0.30 0.350
1
2
3
4
5
0 1 2 3 4 520
40
60
80
100
120
140
160Carbonaceous matter
influences reflectance
Carbonaceous matter
associated with METALS
Org
an
ic c
arb
on
%
Co
pp
er
pp
m
Reflectance visible average Organic carbon %
What are the sources for these metals and carbon particles ?
Bingham Canyon copper mine
Salt Lake City
Salt Lake CityPark City
DOS sites
Milford Flat dust March 2009 Mark Miller, USGS
Can we do anything to mitigate or minimize dust problems ?
We need to know where it’s coming from, and why ?
Can we do anything to mitigate or minimize dust problems ?