© center for snow and avalanche studies photo by chris landry dust on snow: where does it come from...
TRANSCRIPT
© Center for Snow and Avalanche StudiesPhoto by Chris Landry
Dust on snow: Where does it come from ?
What’s in it?Examples from the Wasatch Range (Utah)and the San Juan Mountains (Colorado)
R.L. Reynolds, H.L. Goldstein, C. Landry, T.H. Painter, C. Flagg, R.F. Kokaly, G. Breit,
M.E. Miller, R. Bogle, B. Moskowitz, K. Yauk,M. Redsteer, R.T. Pelltier
U.S. Geological SurveyCenter for Snow and Avalanche StudiesJet Propulsion LaboratoryUniv. of Minnesota, Inst. for Rock MagnetismNational Park Service
© Center for Snow and Avalanche Studies
Photo by Chris Landry
• Decreases albedo of snow cover
• Triggers earlier and faster snow melt
• Leads to smaller late-season water supplies
Tom Painter, Jeff Deems, Chris Landry
Dust on snow coverWHY CARE?
Libya
We can detect dust sources in several ways
Wind models and back-trajectory analysis of air masses
Where does dust come from ?
Phoenix Jul 2011
Direct observation
NW Africa
Dust storm over Colorado & Kansas, April 8, 1999
Satellite images
April 2008
Wasatch R
ange
Great Salt Lake
Salt Lake City
Dust
Dust
Satellite images capture only the biggest dust storms in the West(and not at night or under cloud cover)
MODIS, NASA
DOS sites
Wasatch Range Utah
Locations
DOS sampling [2009-2010] and studies by Tom Painter, McKenzie
Skiles, Annie Bryant(JPL, UCLA, & Univ. of Utah)
Bingham Canyoncopper mine
Sevier Lake
Milford Flat
Salt LakeCityGreat Salt
Lake Desert
Wasatch
Ran
ge
Blind Hollow
Five DOS sites
Dust-on-Snow (DOS)
sites
Some dust source areas
Bingham Canyoncopper mine
UtahN
evad
a
© 2012 Google
Right side: Area treated with Plateau herbicide to kill exotic annual plants, then seeded with rangeland drill
Left side: Untreated patch
Lake Bonneville sedimentsLake Bonneville sediments Mark Miller
Dust from Milford Flat – Site of the Largest Wildfire in Utah History
Aridity (P/PET)(UNESCO classes)
AridSemiaridSubhumidHumid
Size:>360,000 acres~1,500 km2
Mark Miller
Milford FlatFire
Factors that promote dust emission from burn area
• Soils – Old lake sediments (silt and sand)
• Climate – arid and windy
• Landscape – high degree of wind exposure with wind corridors
• “Rehabilitation” ($25M) = Disturbance
WIND
4 Mar 09,wind speed 13 m s-1
Dust sampler ~25 m away
Horizontal dust flux at 1-m height,prior to peak of storm 234,200 g m-2 day-1
(~515 lbs)
Very little dust from burned, untreated
soil
Massive dust emission from treated soil
Sevier Lake playa, UT
Milford Flat, UTOld lake sediment + basalt, etc.
Salt-mineral dust
March 2009
Tom Painter, McKenzie Skiles, Annie Bryant
April 30, 2009 Alta, Utah
Dust layersDOS
April 2008
Wasatch R
ange
Dust
?
?
Sources to Sink
Can Dust-on-Snow (DOS)
composition fingerprint
dust sources ?
© Center for Snow and Avalanche Studies -Chris Landry
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 ?
We need to know where it’s coming from, and why ?
Dust-risk maps for land management
Aeolian dunes overfine-grained lacustrine deposits
Aeolian dunes overlacustrine gravel
Fine-grainedlacustrine deposits
Aeolian dunes andfine-grained lacustrine deposits
Area of fine-grained sediment--Lake Bonneville extent
~ 16,000 yrs ago
Wind Event: 17 Mar 2012, 1400 MDT
1.1-km resolution
Map areas where soil & wind would combine to generate dust after surface disturbance
Wind Field
Milford
Create GIS maps showing risks of
disturbing & rehabilitating land
NV
UT
ID
Dust from NE Arizona is deposited on Colorado mountain snow cover
GOES
MODIS image April 3, 2009
Northeastern Arizona
Moderate Resolution Imaging Spectroradiometer
Dust from the southern Colorado Plateau—the biggest dust sources
today in the U.S.
Early Afternoon MODIS Image April 3, 2009 Northeastern Arizona
Black Mesa
Little Colorado R.
Grand Canyon
Moderate Resolution Imaging Spectroradiometer
ChuskaMtns
next slide
Tucker Flat, near Winslow, ArizonaLittle Colorado River dust corridor
4/27/2009 Jon Mason
Photo by Doug Barnum USGS Apr. 28, 2010
Dust from the southern Colorado Plateau
to Colorado snow cover
Dust-on-Snow layers WY2003-2010
SASP San Juan Mts, Colorado
Snow-layer studies by Chris Landry
2011
2002 2004 2006 2008 2010 2012
0
2
4
6
8
10
12
14
Year
Eve
nts
DOS events since 2003
12
Why dust from southern Colorado Plateau?
Physiographic setting (dry, windy)
Tucker Flat 4/27/2009
Little Colorado River
Many sources: many grazed, many not
Collaboration with M. Redsteer
Cholla power plant18k acre feet yr-1
Is dust load increasing ? YES, but WHY ?
• Regional groundwater withdrawal ?
• Land-use practices (overgrazing) ?
• Regional aridity increasing?
• Drought -- ongoing
Jon Mason
Why dust from Four Corners?
Long history of wind erosion / dust emission
Oct. 2010
very old dunes
modern dunes
Why dust from Four Corners?
A major dust source – never grazed
Toolani Lake 8/5/2012
Land-use practices (overgrazing) ?Many sources: many grazed, many not
A major dust source – never grazed Tyende basin Oct. 2010
Dust is increasing across the West, apparently responding to increasing long-term aridity & current drought
Canyonlands UT
Mesa Verde CO
Vernal UT
0
100
200
2000 20101980 1990
Visibility below 3000 meters
Janice Brahney, Univ. Colorado
2002 2004 2006 2008 2010 2012
0
2
4
6
8
10
12
14
Dust on Snow events, SASP site
Data from Chris Landry, CSAS
Year
Ev
en
ts
DOS events since 2003
In the Jemez Mts (NM), 2000-2006 was the driest 7-yr period during past 1200 yrs
Touchan et al. 2011
13 23 6 23
Dust-on-snow
N=
100
50
0
Colorado
New Mexico
Utah
Arizona
nanohematite
goethite
Dominant iron oxide from Reflectance Spectroscopy
Fe oxides are abundant in DOS.
We can identify the dominant source region for a DOS layer based on
dominant Fe oxide mineral
Two coal-fired power plants
~150
km
Fly ash indicates inputs from combustion of coal
Fly ash in dust-on-snow San Juan Mtns
15 mm
Fly ash
“Black carbon” in San Juan Mtn
Dust-on-Snow?
SASP WY 11 San Juan Mtns DOScollected by Chris Landry
Coal particle in San Juan Mtn DOS
open pit?feed coal?
natural dust source?
But from what source:
SEM analysis by George Breit
Photo by Doug Barnum USGS Apr. 28, 2010
Dust from the southern Colorado Plateau
Can we do anything to mitigate or minimize dust problems ?
Can we do anything to mitigate or minimize dust problems ?
Photo by Doug Barnum USGS Apr. 28, 2010
Dust from the southern Colorado Plateau
• Stable soil surfaces (perennial vegetation and biologic soil crust)
• Stable sand dunes (veg cover)
• Invasive plants (temporary; not during droughts)
• High soil moisture
• High groundwater levels
to Colorado snow cover
Factors that suppress dust emission
Photo by Doug Barnum USGS Apr. 28, 2010
Dust from the southern Colorado Plateau
Can we do anything to mitigate or minimize dust problems ?
Can we do anything to mitigate or minimize dust problems ?
Will, Knowledge, Resources, Collaboration