Solar Induced Stratospheric Effects

SORCE Science Meeting, Durango/CO
Wednesday, 14th September 2005
Solar Induced Stratospheric Effects
Katja Matthes1&2,
Kunihiko Kodera3, Yuhji Kuroda3, and Ulrike Langematz1
[email protected]
1 Freie
Universität Berlin, Institut für Meteorologie, Berlin, Germany
2 National Center for Atmospheric Research, Boulder, Colorado, USA
3 Meteorological Research Institute, Tsukuba, Japan
FU Berlin
Marie Curie Outgoing
International Fellowship
Outline

Mechanism – Influence of the 11-Year Solar Cycle on
the Middle Atmosphere
Observed Modulation of the PNJ and BDC

Transfer of the Solar Signal from the Stratosphere
to the Troposphere

Tropospheric Signal for the 11-Year Solar Cycle and
the Maunder Minimum
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Mesosphere
Mechanism – Influence
of the 11-Year Solar Cycle
UV radiation
Direct influence
on temperature
Stratopause
Change of meridional
temperature gradient
Gray et al. (2001a,b)
Influence on
ozone
Stratosphere
SAO
Kodera and Kuroda (2002),
Hood (2004)
QBO
Labitzke (1987), Labitzke and van Loon (1988)
Transfer of signals?
Tropopause
Troposphere
?
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Circulation changes
(wind, waves, meridional
BD circulation)
Change
of Hadley cell
?
?
Change
of Walker circulation
?
Labitzke and van Loon (1988), Kodera (2002, 2003),
Gleisner and Thejll (2003), van Loon et al. (2004)
?
Indirect influence,
difficult to measure
?
?
Model and Experimental Description
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The FUB Climate Middle Atmosphere
Model (FUB-CMAM)
Basic model:
ECMWF/ECHAM T21-L19
Horizontal
resolution:
Vertical resolution:
T21 (5.6°x5.6°)
L34, hybride coordinates,
∆z = 3.5 km in middle atmosphere (MA)
0.0068 hPa (~84km)
Top:
 full radiation scheme in troposphere and middle
Physics:
Ocean:
Ozone:
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atmosphere
 Rayleigh friction
 hydrological cycle in troposphere
climatological SSTs
climatology (update of Fortuin and Langematz, 1994)
11-Year Solar Cycle
Total Solar Irradiance W/m2
1369
1368
0.1 %
1367
1366
1365
1364
1363
78 80
82 84
86 88 90 92
94
96 98
00
02 04
Fröhlich (2000), update: http://www.pmodwrc.ch/solar_const/solar_const.html
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Percentage UV Radiation Differences
between Solar Maxima and Minima
Implementation of spectral solar irradiance changes between solar max and min
Solar maximum:
more UV radiation
5-8 %
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Data from Lean et al. (1997)
Ozone Variability between Solar Max und Min
Use of solar induced percentage ozone changes between solar max and min
� calculated off-line with 2D model
� applied to GCM background ozone climatology
Solar Max:
more UV radiation
=> more ozone
Annual Mean
+3 %
+3 %
Data from Haigh (1994)
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Experimental Design
Solar Maximum
Solar Minimum
15 years
QBO east
QBO west
• prescribed spectral solar UV irradiance changes for solar max and min
(Lean et al., 1997)
• prescribed solar induced ozone changes for solar max and min,
calculated with 2D model (Haigh, 1994)
• prescribed equatorial winds for QBO east and west from observations
(Gray et al., 2001)
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Annual Mean Differences (Max-Min)
Shortwave Heating Rate (K/d)
Matthes et al. (2004)
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Temperature (K)
Observed Solar Signal in
Stratospheric Temperatures
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Observed Annual Mean Solar Temperature Signal I
SSU/MSU4 (1979-2003)
+ 0.9 K
Courtesy of Bill Randel (2005)
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Observed Annual Mean Solar Signal in Temperature II
ERA40 (1979-2001)
+ 1.75K
+ 0.5K
Crooks and Gray (2005)
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The Transfer from the Upper
to the Lower Stratosphere
and to the Troposphere
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Observed Modulation of the PNJ and BDC
Early
Winter
Anomalies
PNJ and BDC
modulation during NH
winter confirmed with
GCM (Matthes et al.,
2004)
‒ f v* ∇•F
?
1000
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Eq
Kodera and Kuroda (2002)
Modulation of the PNJ: High Latitudes
zonal mean wind u (max-min)
monthly mean
stratospheric response
tropospheric response
Study transition period from significant stratospheric
to significant tropospheric effects
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Modulation of the PNJ: High Latitudes
10day mean wave-mean flow interactions (max-min)
u
EPF
stratospheric waves
(direct solar effect)
tropospheric waves
(response to stratospheric changes)
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Matthes et al. (2005)
High Latitude Surface Signal
monthly mean geop. height and temperature differences (max-min) –
1000hPa
+
+
no clear, significant
surface signal
+
-
+
well ordered significant
surface signal (AO-like pattern)
surface signal
weakens,
changes sign
significant tropospheric effects related to wave forcing
changes in the stratosphere and troposphere that induce
changes in mean meridional circulation and surface pressure
FU(Matthes
Berlin
et al., 2005)
Modulation of the BDC
Correlations: - Vertical Component of EPF (60N/10 hPa)
in December and January Temperature
Absolut (Min)
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Þ less wave forcing at high lats
Þ lower temperatures at high lats & higher
temperatures at low lats => weaker BDC
Modulation of the BDC: Low Latitude Effect
monthly mean w and T differences (max-min) 8S
dynamical heating in
tropical lower
stratosphere
increased stability,
lower tropopause
effect on vertical
motions in troposphere,
strongest in January
consistent with simplified
GCM experiments of
Thuburn and Craig (2000)
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Tropospheric Signal in a Maunder
Minimum vs. Present Day Simulation
Present day simulation:
[PD]
20 years
PD solar mean insolation
PD atmospheric composition
PD sea surface temperatures
Maunder Minimum simulation: [MM]
15 years
MM solar mean insolation
MM atmospheric composition
MM sea surface temperatures
„Climate change between MM and PD“ ≅ statistical mean difference
between MM and PD simulations
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Annual Mean Surface Temperature Change
FUB-CMAM: MM minus present-day
-3.5
Langematz et al. (2005)
NH:
FUB-CMAM:
Proxy data:
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ΔT = -0.86 K
ΔT = -0.6 to -1 K
(Palmer, 2002)
2
NASA-GISS GCM: MM minus pre-industrial
-1.31
Shindell et al. (2001)
- Temperature change patterns
determined by solar forcing
- Magnitude of temperature signal
enhanced by composition changes
0.9
Conclusions
 Direct 11-year solar signal in the upper stratosphere leads to
modulation of PNJ and BDC that induce indirect circulation changes in
the lower stratosphere (Matthes et al., 2004)
 Significant tropospheric changes follow stratospheric changes:
- AO signal at high latitudes related to PNJ modulation
- influence on vertical motions (Hadley and Walker circulation) at low
latitudes related to dynamical heating in the lower stratosphere due
to a modulation of the BDC
- indirect tropospheric effects because of fixed SSTs
(Matthes et al., 2005)
 Significant tropospheric global and regional response during Maunder
Minimum simulation is in line with reconstructed climate change
between MM and present day; response is a combination of MM
insolation, SSTs and chemical composition changes (Langematz et al.,
2005)
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Thank you
for your attention!
FU Berlin
REFERENCES
Crooks and Gray (2005), Characterization of the 11-Year Solar Signal Using a Multiple Regression
Analysis of the ERA-40 Dataset, J. Climate, 18, 996–1015.
Hood, L.L. (2004), Effects of Solar UV Variability on the Stratosphere, in ‘Solar Variability and its
Effects on Climate’, edited by J. Pap and P. Fox, AGU Monograph Series, 141, 283-303.
Kodera, K. and Y. Kuroda (2002), Dynamical Response to the Solar Cycle, J. Geophys. Res., 107,4749,
doi:10.1029/2002JD002224.
Langematz, U., A. Claussnitzer, K. Matthes, and M. Kunze (2005), The Climate during the Maunder
Minimum: a simulation with the Freie Universitaet Berlin Climate Middle Atmosphere Model
(FUB-CMAM), J. Atm. Sol.-Terr. Phys., 67, 55-69.
Matthes, K., U. Langematz, L. Gray, K. Kodera, and K. Labitzke (2004), Improved 11-Year Solar
Signal in the Freie Universitaet Berlin Climate Middle Atmosphere Model (FUB-CMAM), J.
Geophys. Res., 109, D06101, doi:10.1029/2003JD004012, 2004.
Matthes, K., Y. Kuroda, K. Kodera, and U. Langematz (2005), The Transfer of the Solar Signal from
the Stratosphere to the Troposphere: Northern Winter, J. Geophys. Res., under review.
Van Loon, H., G.A. Meehl, J. Arblaster (2004), A decadal solar effect in the tropics in July-August,
J. Atmos. Sol.-Terr. Phys., 66, 1767-1778.
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