RED DUST SNOWFALL EVENT
FEBRUARY 15, 2006
OVERVIEW and RELATED RESEARCH at NIWOT RIDGE, COLORADO
MARK LOSLEBEN, THOMAS PAINTER, ALLEN TOWNSEND, KURT CHOWANSKI, LUCAS
ZUKIEWICZ,
OUTLINE
Event
Origin/Synoptic Conditions during Event
Avalanche Implications
Measurements
Observations of Dust –on-Snow Effects
Snow pack melt rate
Energy transfer into snow pack
Alteration of melt-water pathways (Ice column development)
Differential radiative impacts of fine vs. coarse particle size
Future Implications (Positive Feedback)
Decreased southwestern US Water Supply
Increased dry, summer season
Altered phenologies
Shifted ecological zones
The Event
On the night of February 15-16, 2006, 6.4 cm (2 ½”/0.20”SWE) of snow
fell at C1.
The event began about 7 PM on the 15th and was virtually over by
midnight.
The lower one half was red, the upper was visibly white with a sharp
distinction between the two.
Begining February 21, 2006, westerly winds mixed the red dust layer with
the overlying white snow, or removed it completely.
Related Events
“In Europe reddish precipitation originating from North Africa has been known for
hundreds of years (referred to as "blood rain" in Germany), and seems to happen
every few years (transported right across the Mediterranean).” Klaus Wolter.
Behind Marr Bldg
Feb 20
Feb 17
Feb 20
Feb 21
17 Feb 2006 above Soddie
AVALANCHE
“Here is a shot of my compression test column. The Column failed with only two wrist
taps, on top of the dust layer.
Cheers, Halsted “
Colorado Avalanche Center
"SNOWPACK DISCUSSION -- A layer of dust came in with the snow yesterday
across most of the state from the San Juan Mountains to the Front Range.
Strong SW winds picked up the dust in the 4-Corners region where drought
conditions have left the ground bare. We have received reports of small and
shallow slabs releasing on this layer. Dust layers can be associated with
weak layers if the conditions are right after deposition. We will have to
wait and see how the snow around this layer reacts in the next few days."
From SW Colorado
“we get these dust layers almost every season, usually in spring, and they are the bane
of the snowpack!
obviously, they radically change the albedo, so melt rates are greatly increased (bad!).
and, in turn, the dust also creates strong temp gradients in the uppermost pack which
causes increased near-surface faceting which creates cool NSF crystals which, when
buried, become a weak, fast and clean interface...(bad!)”.
Mark Rikkers
ORIGIN
Start of Event
End of Event
MEASUREMENTS
Snowpits; depth, density, temperature, stratigraphy
Dan Muhs, USGS,
“Particle size analyses, mineralogy, and rare
earth element geochemistry … comparison with the alpine
and subalpine soils that Jim (Benedict) and I have studied in the Front
Range.”
Mark Williams, INSTAAR: NADP suite of cations/anions, minerals;
Sr-86/87 (Phil Veplanck); C13 (Ruth Ley).
David Clow, USGS: carbonate (acid neutralizing capability).
Tom Painter, CIRES, CU, Effect of particle size on radiative response of
snowsurface to melting.
Allen Townsend, INSTAAR, Ecological effects: plant and soil response and
change, surface melt rate.
Steven Fassnacht, CSU: Surface roughness
Temperature and
light level profile
Julian Days
154.71
152.95
151.19
149.44
147.68
145.92
144.17
142.41
140.65
138.90
137.14
135.38
133.63
131.87
130.11
128.35
126.60
124.84
123.08
121.33
119.57
117.81
116.06
114.30
112.54
110.78
109.03
107.27
105.51
103.76
102.00
Solar Intensity (lum/ft²)
Time Series Solar Intensity Julian Days 102-156
350
300
250
200
150
250cm Height
230cm Height
210cm Height
190cm Height
170cm Height
85cm Height
0cm Height
100
50
0
Julian Day 2006
154.26
151.31
148.36
145.41
142.46
139.51
136.56
133.60
130.65
127.70
124.75
121.80
118.85
115.90
112.94
109.99
107.04
104.09
101.14
98.19
95.24
92.28
89.33
86.38
83.43
80.48
77.53
74.58
71.63
68.67
Temperature °C
Temperature Series
10.000
8.000
6.000
4.000
2.000
0.000
-2.000
-4.000
-6.000
0cm Ground
85cm Height
170cm Height
190cm Height
210cm Height
230cm Height
250cm Height
-8.000
Temperature Series April3-April12
14
0.50
0.00
12
-0.50
Temperature deg. C
-1.50
8
-2.00
6
-2.50
-3.00
Solar Intensity (lum/ft²)
10
-1.00
Solar Intensity
250cm Height
230cm Height
210cm Height
190cm Height
170cm Height
85cm Height
0cm Height
4
-3.50
2
-4.00
102.87
102.53
102.19
101.85
101.51
101.17
100.83
100.49
100.15
99.81
99.47
99.13
98.78
98.44
98.10
97.76
97.42
97.08
96.74
96.40
96.06
95.72
95.38
95.04
94.70
94.36
94.02
93.68
93.34
0
93.00
-4.50
Julian Day
On JD 94, the snowpack absorbed 6709 J/M2 in one hour. This is a rate of 112 J/M2 per minute.
Day of Year
DOY 94: Energy infusion rate of 112 J/m2 per minute brought the snow pack to isothermal
in one hour!
111.23
110.01
108.80
107.58
106.37
105.15
103.94
102.72
101.51
100.29
99.08
97.86
96.65
95.43
94.22
93.00
91.78
90.57
89.35
88.14
86.92
85.71
84.49
83.28
82.06
80.85
79.63
78.42
77.20
75.99
74.77
73.56
72.34
71.13
69.91
68.69
J/m2
Snow Pack Cold Content
2000
0
-2000
-4000
-6000
-8000
-10000
-12000
-14000
Ice Columns
Indicators of melt-water flow paths
Altered form in red snow layer
Five ice columns randomly selected
for both types of snow, excavated,
measured for surface diameter,
length, shape, and where the
column terminated. Ice columns
from red snow were significantly
shorter than from white snow (p =
.0001), with red snow columns
having a mean height of 16.4 cm.
Ice columns from white snow were
longer, mean length of 60 cm. The
red snow columns had a conical
shape and maximum diameter
occurring at the top of the column.
The white snow columns had a
more consistent uniform shape from
surface to bottom before ending in
ice lenses.
We speculate that increased melt rates in the red snow areas: (1) increased the
volumetric water content; (2) resulted in a more uniform movement of water
through the snowpack; (3) increased rates of liquid water movement through the
snowpack; and (4) melted the pre-existing ice columns from top to bottom
because of the increased latent heat of fusion associated with the increased
volumetric liquid water content and higher rates of liquid water movement
through the snowpack.
ICE COLUMNS
Red Snow: shorter (16.4 cm), fatter
White snow: longer (60 cm), thinner
Both: terminated at ice layer
Spring Snow Surfaces
Red = smooth; White = rough (10-30 cm)
EFFECTS ON SOIL AND VEGETATION
Surface melt accelerated until a red/white snow surface
equilibrium level was reached at ~30 cm differential. At this
point, the albedo of the red and white snow surfaces was
similar.
Dust scattered over snow on 12 May 2006.
“June 2, 1200 mst. The fine dust plot (first one) is much deeper (~20 cm) and
darker than the coarse plot, which is almost indistinguishable from the
background now. The impression is that the coarse dust has melted into the
snow, dropping away from the surface and thus no longer radiatively as active as
the fine dust, which is obviously still on the surface.
June 8, 0700 mst. Fine dust plot melted a hole through the snowpack.”
MarkLosleben
SUMMARY
Suggested Effects of Red Dust on/in Snow pack, Niwot Ridge
IMMEDIATE (RADIATIVE) EFFECTS
- Dust layer can be radiatively activated 20-30 cm below the surface
- Increases surface melt rates until “normal”
background albedo levels are reached; ~30 cm
differential on Niwot Ridge, spring 2006.
- Alters sub-surface melt water flow paths
- Increases energy flux through snowpack
- Particle size matters
LONGER-TERM POTENTIAL EFFECTS
- Possible soil composition and soil water chemistry
changes (study in progress).
CONCLUDING THOUGHTS
Dust-in-snowfall events present another avenue to reduce snow pack.
Possible Scenario:
A warmer, drier climate increases dust avaliablity
Gustier frontal passages transport this dust further, frequently reaching the
upper Colorado River Basin
Potential Impacts:
Reduced SW US water supplies (less snow pack)
Increased dry, summer season length,
Altered phenology
Shifted ecological zones
Positive feedback that further increases dust supply.
[By 2036, there will be an additional 86 tons per day of air-borne dust from the
dry bed of the Salton Sea, if remedial actions are not taken (SW Hdrol, v.5. No
5).]