THE RESPONSE OF SNOWPACK TO CLIMATE WARMING IN THE PYRENEES
García-Ruiz et al., 2014. The Holocene
-86%
250
Superficie (hectareas)
200
150
100
50
0
PEH
2008
1981
2011
1981
Trends 1950-2012
Clima
Precipitation
Temperature
Climate projections end 21st century
December
January
February
March
April
Izas experimental basin
Snow and climate change
Peak SWE
Snow and climate change
Peak SWE:
‐54%
Date of MSWE:
‐32 days
Duration of snowpack
‐61 days
Scenario A2 (high GHGs emissions), period 2070-2100
Snow and climate change
Maximum snow accumulation MSWE
Date of MSWE
Duration of snow cover
Snow and climate change
3000 m a.s.l.
2500 m a.s.l.
2000 m a.s.l.
1500 m a.s.l.
Snow and climate change
Simulated change (HIRHAM model) in Peak SWE in the Pyrenees for scenarios B2 y A2
A2
B2
Periodo 2070-2100
Snow and climate change
Change in temperature
Change in precipitation
4
-50
-75
Temperature change (ºC)
3
-50
-50
-25
-50
2
-25
1
0
0
-50
-25
25
-1
-2
-25
0
0
50
-25
25
0
75
30
20
10
0
0
-10
-20
-3030
Precipitation change %
mm
0
200
400
600
800
1000
1200
Maximum snow accumulation
20
10
0
-10
-20
-303
Precipitation change %
Days
0
50
100
150
200
Duration of the snowpack
Sensitivity of snow to climate variability and change in Izas station (2056 m s.n.m.)
Spatial differences in snow accumulation and
melting processes
Slope angle and aspect are large contributors to the
spatial variability of the surface snow energy balance, and
condition the partition in their components: radiative,
sensible and latent heat fluxes
Elevation
Slope
Radiation
Elevation (m)
HRU 1
HRU 2
HRU 3
Slope
Bare soil
Radiation Soil Depth
min
mean max
(º)
%
(Mj/m2/day)
(cm)
2062
2117
2056
2171
2194
2119
2288
2261
2196
21.93
18.86
13.93
25.57
8.65
30.08
1864.24
1297.82
1516.06
51.66
50.22
48.81
Accumulated SWE
25
HRU 1
75
50
HRU 2
3
25
-50
-25
0
1
-50
-25
-25
0
-50
-25
25
-1
0
50
25
75
-2
30
20
10
0
-10
Precipitation change %
mm
0
200
400
600
800
1000
1200
50
0
-20
-30 30
20
25
10
0
25
0
Precipitation change %
mm
0
200
400
600
800
1000
1200
1400
1600
-20
25
-3030
20
10
0
-10
Precipitation change %
-20
-3030
20
10
0
0
-10
Precipitation change %
-1
Days
mm day
0
50
100
150
200
-20
-10
-10
0
0
10
10
0
0
-10
-20
-25
0
0
-25
0
25
-25
-30
-25
0
0
-40
-30
-50
-25
-25
-25
-40
-50
-50
5
-2
HRU 3
-50
-50
10
25
50
-50
2
0
10
50
-50
0
0
25
75
-10
-25
0
5
-2
Temperature change (ºC)
-10
0
25
-20
-50
0
-75
3
-25
0
5
-2
50
-30
-20
-25
25
0
-1
-40
0
25
0
10
0
-30
-25
-50
0
-50
-5
0
-25
-10
0
10
25
-25
-25
0
-20
-10
-50
-25
1
-30
-20
-50
-50
-50
2
-2
4
50
75
25
-75
-50
0
25
0
-2
4
Temperature change (ºC)
0
-30
5
-2
-2
5
50
-1
25
0
25
0
-25
0
-25
0
0
0
-25
-25
-5
0
-25
25
-50
-5
0
5
-2
Termperature change (ºC)
0
1
-40
-50
-25
2
0
-5
-25
-50
DRIFT
-40
-50
3
Wind drift
MELT
-50
-50
-7
5
-50
Snowmelt rate
DSP
ASWE
MSWE
4
-25
Duration of snowpack
-50
Max. SWE
Termperature change (ºC)
Results
0
5
10
15
20
-20
20
-3030
20
20
10
0
-10
-20
Precipitation change %
mm month
0
10
20
30
40
50
-1
-30
For each site SWE is simulated considering incoming radiation modified according to N, S, NE, NW, SE, SW and flat areas
From daily series MSWE and DSP
are obtained for each year, aspect
and warming scenario
40
-2
Direct + Diffuse clear sky radiation (Wm )
Then simulations are conducted
assuming a warming of 1º, 2º and
3ºC
30
20
10
0
O
N
D
J
North aspect
South aspect
Flat
F
M
A
My
NE and NW aspects
SE and SW aspects
Jn
Validation
3.5
Izas
3.0
O
S
Bonaigua
O
S
Sasseuba
Perafita
O
O
S
S
Bony Neres
O
MSWE
S
Snow depth (cm)
2.5
2.0
1.5
1.0
0.5
MBE
MAE
-0.03
0.4
-0.39
0.41
Izas
Bonaigua
O
S
-0.39
0.41
0.11
0.23
0.14
0.21
0.0
300
O
S
Sasseuba
O
S
Perafita
O
S
Bony Neres
O
DSP
S
Snow duration (days)
250
200
150
100
MBE
MAE
50
10.3
16
5.8
11.4
-12.6
14.6
12.5
16.8
-2.7
16.2
Observed (O) and simulated (S)
maximum annual snow depth (upper
panel) and duration (lower panel) of the
snowpack. Horizontal lines indicate the
interannual mean
Effect of aspect on MSWE and DSP
40
Izas
Difference in DSP compared
to flat area (days)
Difference in MSWE compared
to flat area (%)
40
20
0
-20
-40
E
SE
S
SW
W
NW
N
NE
Izas
20
0
-20
-40
E
SE
S
SW
W
NW
N
Long-term average difference (%) in the annual maximum snow
accumulation (MSWE) and snow duration of the snow pack (DSP) for
each slope aspect compared with flat conditions.
NE
Effect of aspect on MSWE and DSP
40
Izas
Aspect
vs IzasP1
Aspect
vs
20
Difference in DSP compared
to flat area (days)
Difference in MSWE compared
to flat area (%)
40
IzasP1
0
-20
-40
E
SE
S
SW
W
NW
N
NE
Izas
20
0
-20
-40
E
SE
S
SW
W
NW
N
Long-term average difference (%) in the annual maximum snow
accumulation (MSWE) and snow duration of the snow pack (DSP) for
each slope aspect compared with flat conditions.
NE
Effect of aspect on MSWE and DSP
Effect of aspect on the sensitivity of MSWE and DSP
0
0
B
Decrease in snow duration (days)
Decrease in max acummulation (%)
A
-5
-10
-15
-20
-25
-5
-10
-15
-20
-25
Izas
Bonaigua
Sasseuba Perafita
Bonyneres
North aspect
Izas
South Aspect
Bonaigua
Sasseuba Perafita
Bonyneres
Flat
Sensitivity of the long-term average annual maximum snow accumulation
(MSWE, A) and duration of the snowpack (DSP, B) to an increase of 1°C
for flat areas and slopes with north-facing or south-facing aspects.
0
0
Izas
-5
-10
-15
-20
-25
Sensitivity snow duration (days)
Sensitivity maximum accumulation (%)
Effect of aspect on the sensitivity of MSWE and DSP
Izas
-10
-20
-30
-40
E SE S SW W NW N NE Flat
E SE
S SW W NW N NE Flat
Average sensitivity per 1C of the long-term average annual maximum snow
accumulation (MSWE) and duration of the snowpack (DSP) for each slope
aspect under different magnitudes of warming.
0
0
Izas
-5
-10
-15
-20
-25
Sensitivity snow duration (days)
Sensitivity maximum accumulation (%)
Effect of aspect on the sensitivity of MSWE and DSP
Izas
-10
-20
-30
-40
E SE S SW W NW N NE Flat
E SE
S SW W NW N NE Flat
Average sensitivity per 1C of the long-term average annual maximum snow
accumulation (MSWE) and duration of the snowpack (DSP) for each slope
aspect under different magnitudes of warming.
Effect of aspect on the sensitivity of MSWE and DSP
Average sensitivity per 1C of the
long-term average annual maximum
snow accumulation (MSWE) and
duration of the snowpack (DSP) for
each slope aspect under different
magnitudes of warming.
Effect of aspect on MSWE and DSP
Monthly percentage of the annual melting
in north and south aspects during the
period from March to June in Izas and
Bonaigua stations.
Effect of aspect on MSWE and DSP
0
0
Izas North
Izas South
-10
Sensitivity (%)
Sensitivity (%)
-5
-10
-15
r=0.36
-20
-20
-30
r=0.71
-40
CV:0.59
CV:0.35
-50
-25
0
200
400
600
800
0
1000
Bonaigua North
600
800
-5
Sensitivity (%)
Sensitivity (%)
400
Bonaigua South
-5
-10
r=0.22
-15
CV:0.51
-20
-10
-15
r=0.59
-20
CV:0.57
-25
300
400
500
600
-25
100
Sasseuba North
300
400
500
600
700
Sasseuba South
-5
-10
r=0.72
CV:0.41
-15
Sensitivity (%)
-10
200
0
0
Sensitivity (%)
Correlation between
maximum
annual
snow accumulation
and
its
annual
sensitivity to an
increase of 1°C for
north-facing
and
south-facing slopes.
200
0
0
-20
-30
-20
r=0.79
-40
-25
200
300
400
500
Snow accumulation (mm)
600
700
CV:0.56
200
300
400
Snow accumulation (mm)
500
Effect of aspect on MSWE and DSP
0
0
Izas North
Izas South
-10
Sensitivity (%)
Sensitivity (%)
-5
-10
-15
-25
120
140
-30
r=0.71
r=0.69
-20
-20
CV:0.39
160
180
200
220
-40
CV:0.42
-50
180
240
200
220
240
260
280
0
0
Bonaigua North
Bonaigua South
Sensitivity (%)
Sensitivity (%)
-5
-10
-15
-10
-20
r=0.45
-30
-25
190
r=0.65
CV:0.65
CV:0.64
200
210
220
230
160
240
180
200
220
0
0
Sasseuba North
Sasseuba South
-5
-10
-10
-15
CV:0.28
r=0.83
Sensitivity (%)
Sensitivity (%)
Correlation between
maximum
annual
duration
of
snowpack and its
sensitivity to an
increase of 1°C for
north-facing
and
south-facing slopes.
-20
-20
-30
r=0.78
-40
170
180
CV:0.54
-20
-25
190
200
210
220
Snow duration (days)
230
240
190
200
210
Snow duration (days)
220
230
Conclusions
- Slope aspect was responsible for substantial variability in snow accumulation and the duration of the snowpack.
Simulated variability is different amongst different weather stations and markedly increased with warmer
temperature conditions
- Annual maximum snow accumulation (MSWE) and annual snowpack duration (DSP) showed marked sensitivity
to a warming of 1°C. Thus, the sensitivity of the MSWE in flat areas ranged from 11 to 17% per ºC amongst the
weather stations, and the DSP ranged from 11 to 20 days per ºC.
- A clear increase in the sensitivity of the snowpack to climate warming on those slopes that received high levels of
solar radiation (S, SE and SW slopes) compared with those slopes where the incident radiation was more limited
(N, NE and NW slopes).
- The sensitivity of the MSWE and the DSP increased as the temperature increased, particularly on the most
irradiated slopes.
- Large interannual variability was also observed. Thus, with more snow accumulation and longer duration the
sensitivity of the snowpack to temperature decreased, especially on south-facing slopes.