Introduction
Methodology
Results
Conclusions
Attribution of the 11-year solar cycle in
lower-stratospheric temperature
Ales Kuchar,1,2 Eugene Rozanov,2,3 Will Ball,2,3 Andrea
Stenke,2 Laura Revell,2,4 Petr Pisoft,1 Thomas Peter2
1 Department
of Atmospheric Physics, Charles University in Prague, Czech
Republic
2 IAC ETH, Zurich, Switzerland
3 PMOD, Davos, Switzerland
4 Bodeker Scientific, New Zealand
SOLARIS-HEPPA, Boulder, November 10, 2015
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Take aways
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Take aways
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Take aways
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Motivation #1
• compare model results with observational and reanalysis
data
• SC attribution in equatorial profile for the period 1979–2005
50
MERRA
REF-C1
REF-C2
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
1.0
Attribution of the 11-year SC in TLS
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Motivation #2
• REF-C1 simulation
• SC attribution in zonal mean of temperature for 2 different
periods
1960–2009
0.50
-0.25
-0.50
-0.75
0.25
-0.25
0.25
30
5
0.2
0.50
20
0.25
0.2
5
90
60
30
0
Latitude [deg]
Attribution of the 11-year SC in TLS
30
60
90
0.25
90
60
50
40
-0.2
5
-0.50
-0.75
-0.50
-1.00
-0.75
0.75
-1.00
1000
0.75
0.50
-0.25
100
1.00.75
0
-0.50
10
0.71.00
5
0
0.5
1.0
0
0.75
0.75
-0.75
Pressure [hPa]
0.25
0.50
2.00
1.00.75
0
0
0.5
1
60
0.25
0.25
0.25
Height [km]
1979–2009
0.1
30
0
Latitude [deg]
30
60
10
0
90
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Motivation #2
• REF-C1 simulation
• SC attribution in zonal mean of temperature for 2 different
periods
1960–2009
0.50
-0.25
-0.50
-0.75
0.25
-0.25
0.25
30
5
0.2
0.50
20
0.25
0.2
5
90
60
30
0
Latitude [deg]
Attribution of the 11-year SC in TLS
30
60
90
0.25
90
60
50
40
-0.2
5
-0.50
-0.75
-0.50
-1.00
-0.75
0.75
-1.00
1000
0.75
0.50
-0.25
100
1.00.75
0
-0.50
10
0.71.00
5
0
0.5
1.0
0
0.75
0.75
-0.75
Pressure [hPa]
0.25
0.50
2.00
1.00.75
0
0
0.5
1
60
0.25
0.25
0.25
Height [km]
1979–2009
0.1
30
0
Latitude [deg]
30
60
10
0
90
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Model simulations
• CCMI hindcast simulation REF-C1 and REF-C2
(1960–2009)
Simulation titleSST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1
Hadley
X
1
REF-C2
CESM1-CAM5
×
1
• in addition, sensitivity simulations testing boundary
conditions on the solar signal
Simulation title SST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1-S
Hadley
×
3
REF-C1-S-clim Hadley climatology
×
1
REF-C2-S
CESM1-CAM5
X
1
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Model simulations
• CCMI hindcast simulation REF-C1 and REF-C2
(1960–2009)
Simulation titleSST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1
Hadley
X
1
REF-C2
CESM1-CAM5
×
1
• in addition, sensitivity simulations testing boundary
conditions on the solar signal
Simulation title SST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1-S
Hadley
×
3
REF-C1-S-clim Hadley climatology
×
1
REF-C2-S
CESM1-CAM5
X
1
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Model simulations
• CCMI hindcast simulation REF-C1 and REF-C2
(1960–2009)
Simulation titleSST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1
Hadley
X
1
REF-C2
CESM1-CAM5
×
1
• in addition, sensitivity simulations testing boundary
conditions on the solar signal
Simulation title SST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1-S
Hadley
×
3
REF-C1-S-clim Hadley climatology
×
1
REF-C2-S
CESM1-CAM5
X
1
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Model simulations
• CCMI hindcast simulation REF-C1 and REF-C2
(1960–2009)
Simulation titleSST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1
Hadley
X
1
REF-C2
CESM1-CAM5
×
1
• in addition, sensitivity simulations testing boundary
conditions on the solar signal
Simulation title SST/SIC bound. cond.Volc. erupt.# of ens. memb.
REF-C1-S
Hadley
×
3
REF-C1-S-clim Hadley climatology
×
1
REF-C2-S
CESM1-CAM5
X
1
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Multiple linear regression (MLR)
Regression model:
Y (t) = α + β SAD(t) + γ SOLAR(t)
+δ1 QBO1 (t) + δ2 QBO2 (t) + ENSO(t)
(1)
+ζ TREND(t) + e(t).
• using AR2 to remove residual autocorrelation e —
Durbin-Watson test (DWT)
• QBO1,2 and ENSO3.4 index extracted by PCA
• t-test (95% confidence interval)
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
50
MERRA
40
Height [km]
Pressure [hPa]
1
10
30
20
100
Attribution of the 11-year SC in TLS
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
50
MERRA
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
Attribution of the 11-year SC in TLS
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
50
MERRA
REF-C1
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
Attribution of the 11-year SC in TLS
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
50
MERRA
REF-C1
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
Attribution of the 11-year SC in TLS
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
50
MERRA
REF-C1
REF-C2
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
Attribution of the 11-year SC in TLS
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
50
MERRA
REF-C1
REF-C2
SSU
40
40
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
Attribution of the 11-year SC in TLS
Height [km]
10
100
50
MERRA
REF-C1
REF-C1-S [em]
SSU
Height [km]
Pressure [hPa]
1
30
30
20
20
1.5
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
MERRA
REF-C1
REF-C2
REF-C2-S
SSU
50
MERRA
REF-C1
REF-C1-S [em]
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
Attribution of the 11-year SC in TLS
1.5
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
MERRA
REF-C1
REF-C2
REF-C2-S
SSU
50
MERRA
REF-C1
REF-C1-S [em]
REF-C1-S-clim
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
Attribution of the 11-year SC in TLS
1.5
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SC profile in tropical stratosphere (temperature)
• REF-C1 is comparable with available data (MERRA, SSU)
• the solar signal is reduced in TLS (@50 hPa) to 50% in
case of REF-C1-S, further 25% in case of REF-C1-S-clim
for the period 1979–2005
MERRA
REF-C1
REF-C2
REF-C2-S
SSU
50
MERRA
REF-C1
REF-C1-S [em]
REF-C1-S-clim
SSU
40
Height [km]
Pressure [hPa]
1
10
30
20
100
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
Attribution of the 11-year SC in TLS
1.5
1.0
0.5
0.0
0.5
1.0
Annually temperature response [K / (Smax-Smin)]
1.5
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Why?
150
100
20
21
22
23
16
14
12
10
8
6
4
2
0
SAD [µm2 /cm3 ]
200
temperature [K]
SOLAR [sfu]
250
50 Agung + Awu
Fuego
El Chichon Pinatubo
8
REF-C1
6
@50 hPa
REF-C1-S [em]
4
2
REF-C1-S-clim
0
2
4
6
1960
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
time [year]
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
• SC and volcanoes attribution in zonal mean of temperature
for the period 1979–2009
SOLAR
SAD
60
1.00.75
0
0
0.5
0.25
40
-0.50
-1.00
0.75
0.25
0.25
-1.00
90
-0.2
5
10
0.25
60
30
0
Latitude [deg]
Attribution of the 11-year SC in TLS
30
60
30
20
-0.25
-0.50
-0.75
-0.25
100
1000
50
0.25
10
0.71.00
5
0.75
-0.75
Pressure [hPa]
1
2.00
0.50
0.25
Height [km]
0.1
90
90
60
30
0
Latitude [deg]
30
60
0
90
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
• SC and volcanoes attribution in zonal mean of temperature
for the period 1979–2009
SOLAR
SAD
60
1.00.75
0
0
0.5
0.25
40
-0.50
-1.00
0.75
0.25
0.25
-1.00
90
-0.2
5
10
0.25
60
30
0
Latitude [deg]
Attribution of the 11-year SC in TLS
30
60
30
20
-0.25
-0.50
-0.75
-0.25
100
1000
50
0.25
10
0.71.00
5
0.75
-0.75
Pressure [hPa]
1
2.00
0.50
0.25
Height [km]
0.1
90
90
60
30
0
Latitude [deg]
30
60
0
90
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
0.4
0.2
correlation
0.0
0.2
Attribution of the 11-year SC in TLS
1975
1980 1985
initial year
Pinatubo
1970
El Chichon
1965
Fuego
0.8
1960
Awu
0.6
Agung
0.4
1990
1995
2000
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
0.4
0.2
correlation
0.0
0.2
1970
1975
1980 1985
initial year
1990
1995
SOLAR [sfu]
250
200
150
100
20
50 Agung + Awu
Attribution of the 11-year SC in TLS
21
Fuego
El Chichon
22
Pinatubo
23
2000
16
14
12
10
8
6
4
2
0
SAD [µm2 /cm3 ]
1965
Pinatubo
El Chichon
Fuego
0.8
1960
Awu
0.6
Agung
0.4
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
0.4
0.2
correlation
0.0
0.2
1970
1975
1980 1985
initial year
1990
1995
SOLAR [sfu]
250
200
150
100
20
50 Agung + Awu
Attribution of the 11-year SC in TLS
21
Fuego
El Chichon
22
Pinatubo
23
2000
16
14
12
10
8
6
4
2
0
SAD [µm2 /cm3 ]
1965
Pinatubo
El Chichon
Fuego
0.8
1960
Awu
0.6
Agung
0.4
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
0.4
0.2
correlation
0.0
0.2
1970
1975
1980 1985
initial year
1990
1995
SOLAR [sfu]
250
200
150
100
20
50 Agung + Awu
Attribution of the 11-year SC in TLS
21
Fuego
El Chichon
22
Pinatubo
23
2000
16
14
12
10
8
6
4
2
0
SAD [µm2 /cm3 ]
1965
Pinatubo
El Chichon
Fuego
0.8
1960
Awu
0.6
Agung
0.4
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
SOLAR and volcanic (SAD) aliasing
0.4
0.2
correlation
0.0
0.2
1970
1975
1980 1985
initial year
1990
1995
SOLAR [sfu]
250
200
150
100
20
50 Agung + Awu
Attribution of the 11-year SC in TLS
21
Fuego
El Chichon
22
Pinatubo
23
2000
16
14
12
10
8
6
4
2
0
SAD [µm2 /cm3 ]
1965
Pinatubo
El Chichon
Fuego
0.8
1960
Awu
0.6
Agung
0.4
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
temperature response to SC [K/(Smax-Smin)]
Sensitivity to the length of regression window —
model simulations
Attribution of the 11-year SC in TLS
1.0
level: 50.0 hPa (SOCOLv3 REF-C1)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
1.0
level: 50.0 hPa (SOCOLv3 REF-C1)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Attribution of the 11-year SC in TLS
temperature response to SC [K/(Smax-Smin)]
temperature response to SC [K/(Smax-Smin)]
Sensitivity to the length of regression window —
model simulations
1.0
level: 50.0 hPa (SOCOLv3 REF-C1-S [em])
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
level: 50.0 hPa (SOCOLv3 REF-C1)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
temperature response to SC [K/(Smax-Smin)]
1.0
temperature response to SC [K/(Smax-Smin)]
temperature response to SC [K/(Smax-Smin)]
Sensitivity to the length of regression window —
model simulations
Attribution of the 11-year SC in TLS
1.0
level: 50.0 hPa (SOCOLv3 REF-C1-S [em])
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
1.0 level: 50.0 hPa (SOCOLv3 REF-C1-S-clim)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
level: 50.0 hPa (SOCOLv3 REF-C1)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
level: 50.0 hPa (MERRA)
1.0
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Attribution of the 11-year SC in TLS
temperature response to SC [K/(Smax-Smin)]
1.0
temperature response to SC [K/(Smax-Smin)]
temperature response to SC [K/(Smax-Smin)]
temperature response to SC [K/(Smax-Smin)]
Sensitivity to the length of regression window —
model simulations
1.0
level: 50.0 hPa (SOCOLv3 REF-C1-S [em])
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
1.0 level: 50.0 hPa (SOCOLv3 REF-C1-S-clim)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Sensitivity to the length of regression window — DWT
Pn
DWT =
t=2 (et − et−1 )
Pn
2
t=1 et
2
≈ 2(1 − r );
where r is residual autocorrelation.
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Sensitivity to the length of regression window — DWT
Pn
DWT =
t=2 (et − et−1 )
Pn
2
t=1 et
2
≈ 2(1 − r );
temperature response to SC [K/(Smax-Smin)]
where r is residual autocorrelation.
Attribution of the 11-year SC in TLS
1.0
level: 50.0 hPa (SOCOLv3 REF-C1)
0.5
0.0
0.5
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Sensitivity to the length of regression window — DWT
Pn
DWT =
t=2 (et − et−1 )
Pn
2
t=1 et
2
≈ 2(1 − r );
1.0
level: 50.0 hPa (SOCOLv3 REF-C1)
2.2
2.0
1.8
0.5
1.6
0.0
DWT
temperature response to SC [K/(Smax-Smin)]
where r is residual autocorrelation.
1.4
1.2
0.5
AR0
AR2
1.0
0.8
1.0
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Attribution of the 11-year SC in TLS
0.6
1960 1965 1970 1975 1980 1985 1990 1995
initial analysed year ending in 2009
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Conclusions
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Conclusions
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.
Introduction
Methodology
Results
Conclusions
Conclusions
• solar signal in TLS over satellite era is reduced considering
volcanoes (50%) and SST (+25%) correctly
• 1965–2009 sufficient to eliminate volcanic forcing aliasing
in TLS
• significant methodology influence
Attribution of the 11-year SC in TLS
Ales Kuchar et al.