THE RESPONSE OF SNOWPACK TO CLIMATE WARMING IN THE PYRENEES
García-Ruiz et al., 2014. The Holocene
Supe
rfic
ie (h
ecta
reas
)
0
50
100
150
200
250
PEH 2008
-86%
1981
2011
1981
Trends 1950-2012
Precipitation
Temperature
Clima
December January February March April
Climate projections end 21st century
Izas experimental basin
Snow and climate change
Peak SWE
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
1500 m a.s.l.
2000 m a.s.l.
2500 m a.s.l.
3000 m a.s.l.
Snow and climate change
Snow and climate change
Simulated change (HIRHAM model) in Peak SWE in the Pyrenees for scenarios B2 y A2
Periodo 2070-2100
A2
B2
Change in temperature Change in precipitation
Snow and climate change
Sensitivity of snow to climate variability and change in Izas station (2056 m s.n.m.)
3Precipitation change %
-30-20-100102030
-25
-25
00
-50
-50
0 50 100 150 200
DaysPrecipitation change %
-30-20-100102030
Tem
pera
ture
cha
nge
(ºC
)
-2
-1
0
1
2
3
4
-25
-25
-25
25
25
75
-75
-50
-50
-50
0
0
050
0 200 400 600 800 1000 1200
mm
Maximum snow accumulation Duration of the snowpack
Spatial differences in snow accumulation andmelting processes
Slope angle and aspect are large contributors to thespatial variability of the surface snow energy balance, andcondition the partition in their components: radiative,sensible and latent heat fluxes
Slope Bare soil Radiation Soil Depthmin mean max (º) % (Mj/m2/day) (cm)
HRU 1 2062 2171 2288 21.93 25.57 1864.24 51.66HRU 2 2117 2194 2261 18.86 8.65 1297.82 50.22HRU 3 2056 2119 2196 13.93 30.08 1516.06 48.81
Elevation (m)
Elevation
Radiation
Slope
Results
Precipitation change %-30-20-100102030
Precipitation change %-30-20-100102030
Tem
pera
ture
cha
nge
(ºC
)
-2
-1
0
1
2
3
4
Precipitation change %-30-20-100102030
Precipitation change %-30-20-100102030
Precipitation change %-30-20-100102030
Term
pera
ture
cha
nge
(ºC
)
-2
-1
0
1
2
3
4Te
mpe
ratu
re c
hang
e (º
C)
-2
-1
0
1
2
3
4
-25
-25
-25
25
25
75
-75
-50
-50
-50
0
0
0
50
-25
-25
-25
25
25
75
-75
-50
-50
-50
0
0
50
-25
-25
-25
25
25
75
-75
-50
-50
-50
0
0
050
-25
-25
-25
25
25
0
0
50
-50
-50
-25
-25
-25
25
25
0
0
50
-50
-50
-25
-25
-25
25
25
0
0
0
50
-50
-50
MSWEH
RU
1H
RU
2H
RU
3
-25
-25
25
0
0
-50
-50
-25
-25
0
0
-50
ASWE
-25
-25
-25
25
25
75
0
0
050
-50-50
-50
-50
-25
-25
00
-50
-50
DSP
-25
-25
25
25
-50
-50
-50
0
0
50
Term
pera
ture
cha
nge
(ºC
)
-30-30
-10-10
1010
-40-40
-20-20
00
-30-30
-10-10
1010
-20-20
00
-40
MELT
-25
-25
-25-25
0
0
00
25
25
-50
-50
-50
DRIFT
0 200 400 600 800 1000 1200
mm mm0 200 400 600 800 1000 1200 1400 1600
0 50 100 150 200
Days
-30-30
-10-10
1010
-40-40
-20-20
00
2020
0 10 20 30 40 50
0 5 10 15 20
mm day-1 mm month-1
Max. SWE Accumulated SWE Duration of snowpack Snowmelt rate Wind drift
For each site SWE is simulated considering incoming radiation modified according to N, S, NE, NW, SE, SW and flat areas
Dire
ct +
Diff
use
clea
r sky
radi
atio
n (W
m-2
)
0
10
20
30
40
N D J F M A My JnO
North aspectSouth aspectFlat
NE and NW aspectsSE and SW aspects
Then simulations are conductedassuming a warming of 1º, 2º and3ºC
From daily series MSWE and DSPare obtained for each year, aspectand warming scenario
ValidationS
now
dur
atio
n (d
ays)
50
100
150
200
250
300
Izas Bonaigua Sasseuba Perafita Bony NeresO S O S O S O S O S
Sno
w d
epth
(cm
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Izas Bonaigua Sasseuba Perafita Bony NeresO S O S O S O S O S
-0.030.4
-0.390.41
-0.390.41
0.110.23
0.140.21
MBEMAE
10.316
5.811.4
-12.614.6
12.516.8
-2.716.2
MBEMAE
Observed (O) and simulated (S)maximum annual snow depth (upperpanel) and duration (lower panel) of thesnowpack. Horizontal lines indicate theinterannual mean
MSWE
DSP
Effect of aspect on MSWE and DSP
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.
E SE S SW W NW N NE
Diff
eren
ce in
MSW
E co
mpa
red
to fl
at a
rea
(%)
-40
-20
0
20
40 Izas
E SE S SW W NW N NE
-40
-20
0
20
40 Izas
Diff
eren
ce in
DSP
com
pare
d to
flat
are
a (d
ays)
Effect of aspect on MSWE and DSP
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.
Aspect vs IzasP1 Aspect vs IzasP1
E SE S SW W NW N NE
Diff
eren
ce in
MSW
E co
mpa
red
to fl
at a
rea
(%)
-40
-20
0
20
40 Izas
E SE S SW W NW N NE
-40
-20
0
20
40 Izas
Diff
eren
ce in
DSP
com
pare
d to
flat
are
a (d
ays)
Effect of aspect on MSWE and DSP
Effect of aspect on the sensitivity of MSWE and DSP
Dec
reas
e in
sno
w d
urat
ion
(day
s)
-25
-20
-15
-10
-5
0
Dec
reas
e in
max
acu
mm
ulat
ion
(%)
-25
-20
-15
-10
-5
0
North aspect South Aspect
Izas Bonaigua Sasseuba Perafita Bonyneres Izas Bonaigua Sasseuba Perafita Bonyneres
Flat
A B
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.
Average sensitivity per 1C of the long-term average annual maximum snowaccumulation (MSWE) and duration of the snowpack (DSP) for each slopeaspect under different magnitudes of warming.
E SE S SW W NW N NE Flat
Sen
sitiv
ity m
axim
um a
ccum
ulat
ion
(%)
-25
-20
-15
-10
-5
0Izas
E SE S SW W NW N NE Flat-40
-30
-20
-10
0Izas
Sen
sitiv
ity s
now
dur
atio
n (d
ays)
Effect of aspect on the sensitivity of MSWE and DSP
Average sensitivity per 1C of the long-term average annual maximum snowaccumulation (MSWE) and duration of the snowpack (DSP) for each slopeaspect under different magnitudes of warming.
Izas Izas
Sen
sitiv
ity s
now
dur
atio
n (d
ays)
E SE S SW W NW N NE Flat
Sen
sitiv
ity m
axim
um a
ccum
ulat
ion
(%)
-25
-20
-15
-10
-5
0
E SE S SW W NW N NE Flat-40
-30
-20
-10
0
Effect of aspect on the sensitivity of MSWE and DSP
Average sensitivity per 1C of thelong-term average annual maximumsnow accumulation (MSWE) andduration of the snowpack (DSP) foreach slope aspect under differentmagnitudes of warming.
Effect of aspect on the sensitivity of MSWE and DSP
Effect of aspect on MSWE and DSP
Monthly percentage of the annual meltingin north and south aspects during theperiod from March to June in Izas andBonaigua stations.
Effect of aspect on MSWE and DSP
Correlation betweenmaximum annualsnow accumulationand its annualsensitivity to anincrease of 1°C fornorth-facing andsouth-facing slopes.
0 200 400 600 800 1000
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
0 200 400 600 800
Sen
sitiv
ity (%
)
-50
-40
-30
-20
-10
0Izas North Izas South
CV:0.35CV:0.59
300 400 500 600
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
100 200 300 400 500 600 700
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0Bonaigua North Bonaigua South
Snow accumulation (mm)200 300 400 500 600 700
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
Snow accumulation (mm)200 300 400 500
Sen
sitiv
ity (%
)-40
-30
-20
-10
0Sasseuba North Sasseuba South
CV:0.41
CV:0.56
CV:0.51
CV:0.57
r=0.36r=0.71
r=0.22
r=0.59
r=0.72
r=0.79
Effect of aspect on MSWE and DSP
Correlation betweenmaximum annualduration ofsnowpack and itssensitivity to anincrease of 1°C fornorth-facing andsouth-facing slopes.
120 140 160 180 200 220 240
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
180 200 220 240 260 280
Sen
sitiv
ity (%
)
-50
-40
-30
-20
-10
0Izas North Izas South
190 200 210 220 230 240
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
160 180 200 220
Sen
sitiv
ity (%
)
-30
-20
-10
0Bonaigua North Bonaigua South
CV:0.39CV:0.42
CV:0.64 CV:0.65
Snow duration (days)190 200 210 220 230 240
Sen
sitiv
ity (%
)
-25
-20
-15
-10
-5
0
Snow duration (days)170 180 190 200 210 220 230
Sen
sitiv
ity (%
)-40
-30
-20
-10
0
CV:0.54
CV:0.28
r=0.69r=0.71
r=0.45
r=0.65
r=0.83
r=0.78
Sasseuba North Sasseuba South
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 warmertemperature conditions
- Annual maximum snow accumulation (MSWE) and annual snowpack duration (DSP) showed marked sensitivityto a warming of 1°C. Thus, the sensitivity of the MSWE in flat areas ranged from 11 to 17% per ºC amongst theweather 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 ofsolar 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 mostirradiated slopes.
- Large interannual variability was also observed. Thus, with more snow accumulation and longer duration thesensitivity of the snowpack to temperature decreased, especially on south-facing slopes.