Post on 03-Jan-2016
Influences of the 11-year solar cycle on the tropical atmosphere and oceans
Stergios Misios and Hauke Schmidt
Max Planck Institute for Meteorology
TOSCA workshop, 2012
Heading to a solar maximum in 2013
20082013 ?
Should we expect any measurable climatic effect?How does the solar activity influence the Earth’s climate?
Slide 2
Guises of the 11-yr solar cycle
Geomagnetic fluxParticle precipitationGalactic cosmic rays
Total solar irradiance 1 W/m2 or 0.1%
Spectral solar irradianceextreme UV: 100% UV: 4-6%
100 %
10 %
1 %
0.1 %
0.01 %100 nm 1 μm 10 μm
After Gray et al., 2010
Slide 3
Troposphere
Stratosphere
Ocean
Suggested mechanisms
Stratosphere
Adapted from Gray et al. 2010
Total solar irradiance:1 W/m2 at the top of the atmosphere translates to 0.18 W/m2 at the surfaceEnergy balance models predict ~0.1 K global-mean warming !
Spectral solar irradiance:Affects ozoneStratospheric warming of about 1 K
Two main mechanisms:Top-downBottom-up
Slide 4
30°S 30°N
1) How does the 11-yr solar cycle affect the tropical lower stratosphere?
Secondary maximum: real or analysis artifact? Does ocean coupling matter?
2) How does the 11-yr solar cycle affect the tropical atmosphere-ocean system?
El Nino- or La Nina-like?
Research questions
Slide 5
Outline
1) Introduction2) Model description and analysis methodology3) The response of the tropical lower stratosphere to the
SC in ensemble simulations4) The response of the tropical Pacific to the SC in
ensemble simulations5) Synthesis
Slide 6
Model description and analysis methodology Middle Atmosphere version of ECHAM5/MPIOM Detailed stratospheric dynamics: internal QBO Present-day greenhouse gas concentrations
Modifications to simulate a realistic solar cycle forcing Solar spectral irradiances from 1955-2006 (Lean et al., 2000) Solar-induced ozone anomalies from HAMMONIA (Schmidt et al., 2010)
Experiments
CENS: coupled ensemble (11 members, T31L90/GR30L40 )
AENS: uncoupled ensemble ( 9 members, T31L90 )
MENS: mixed layer ocean ensemble (11 members, T31L90 )
CENS-ST: twin to CENS but with stronger forcing in the 185-250 nm band ssssssssssssssssssssssssssssssssssssssssssssssss ( 9 members, T31L90/GR30L40)
CENS-T63: twin to CENS-ST but in a finer horizontal resolution ssssssssssssssssssssssssssssssssssssssssssssssss (15 members, T63L95/GR15L40) Slide 7
22
2
14.37.10)( COcobAOD
Volcb
i iQBOiqbo
bNinoENSObFsolarbtY
ObservationsMERRA reanalysis (1979-2008)ERA-40 reanalysis (1979-2001)
Solar signals are extracted with:MRA model with AR1 (Frame and Gray, 2010):
Multi-channel Singular Spectrum Analysis (MSSA, Ghil et al. 2002)
Model description and analysis methodology
Slide 8
Outline
1) Introduction2) Model description and analysis methodology3) The response of the tropical lower stratosphere (TLS) to
the SC in ensemble simulations4) The response of the tropical Pacific to the SC in
ensemble simulations5) Synthesis
Slide 9
How does the 11-yr solar cycle affect the tropical lower stratosphere?
Secondary maximum: real or analysis artifact? Does ocean coupling matter?
Data: MERRA and ERA-40 Coupled and uncoupled ensembles Ensemble-mean temperature anomalies Ensemble-mean zonal wind anomalies
Methods: AR1 multiple linear regression analysis Regression coefficients are scaled per 100 sfu
See Schmidt et al., 2012, Springer
Slide 10
Discontinuities in MERRA(Modern Era Retrospective-analysis for
Research and Applications)
Solar signal of 1K?
~50 Km
~35 Km
Temperature response
ERA40 (1979-2001) MERRA (1979-2008)
K/100 sfu
MERRA: weaker warming in the lower tropical stratosphere compared to ERA-40Our simulations: lacking of any strong secondary warming in ensemble averages
CENS-T63 ensemble(1955-2006)
Slide 11
Tropical (25S-25N) temperature profiles
Temperature (K/100 sfu)
Lacking of any strong secondary warming in the TLS in all model configurations
Stronger warming throughout the stratosphere in the simulations with amplified UV forcing (185-250 nm)
Trivial sensitivity to ocean coupling
Slide 12
Effects of collinearity
Solar regression coefficients @ 70 hPa
Correlation between F10.7 and Nino-3.4
Positive correlations result in weaker regression coefficients-0.06 K/100 sfu per 0.1 incrementObserved correlation (1979-2003): -0.15
Slide 14
Zonal wind anomalies
Stronger solar heating improves the time evolutionIncreased horizontal resolution gives more realistic evolution
Slide 15
Inter-ensemble variability in February (CENS-ST)
Positive and negative anomalies up to 7 m/s
Slide 16
Summary 1
How does the 11-yr solar cycle affect the tropical lower stratosphere (TLS)?Secondary maximum: real or analysis artifact? None of the experiments shows a temperature response maximum in the TLS in ensemble averages. Many individual ensemble members do show well-formed annual temperature maxima in the TLS.CENS-T63 shows closer agreement with observations but the intra-ensemble variability is very highCollinearity between the ENSO and solar cycle term in the multiple linear regression model biases the estimates
Does ocean coupling matter?The ensemble mean stratospheric solar do not critically depend on the ocean coupling
Slide 17
Outline
1) Introduction2) Model description and analysis methodology3) The response of the tropical lower stratosphere (TLS) to
the SC in ensemble simulations4) The response of the tropical Pacific to the SC in
ensemble simulations5) Synthesis
Slide 18
How does the 11-yr solar cycle affect the tropical oceans?
El Nino- or La Nina-like response ?
Data:Coupled and uncoupled ensemblesSimulations of Bal et al. 2011 with EGMAMEnsemble-mean SST and zonal wind anomaliesLow-order ENSO model
Methods:Regression analysis MSSA
More details in Misios and Schmidt, 2012, J.Clim.
Slide 19
After Meehl et al., 2009
Regression of ensemble mean SST onto the F10.7
SC signature in CENS
Warming up to 0.12 K/100 sfu in CENSWarmer tropical Pacific in MENSRadiative balance calculations do not explain the simulated
warming in CENS
(K/100 sfu)
Slide 21
SC signature in MENS
Comparison of simulations with and without ocean coupling
Dynamic Ocean (CENS) Mixed layer (MENS)
Excess precipitation in the western Pacific Implies eastward displacement of the deep convection
Slide 22
Coupled vs Uncoupled: zonal winds
AtlanticPacificIndian
SC signature in CENS
Westerly anomalies independently of ocean coupling
SC signature in AENS
Slide 23
m/s
/100
sfu
K/1
00 s
fu
SC signature in MENS
ERA-
40 re
anal
ysis
(1
958-
2001
)
AtlanticPacificIndian
Regression of equatorial zonal winds onto the F10.7
CEN
S (1
955-
2006
)
Simulations: westerly anomalies independent of ocean coupling.
Observations?Westerly anomalies are detected in ERA-40 with an AR1-MRA model.
Do westerly anomalies explain the surface warming?
Slide 24
Low order ENSO model
Subsurface
eastern Pacificwestern Pacific
After Jin 1997 with parameters of Timmerman and Jin 2002
advection zonal fluxesheat dtwdT
advection verticalfluxesheat dtedT
stress wind~advection
noise ~ stress wind )e-Tw(T
heat
flu
xes
zonal advection
verti
cal
adv
ectio
n
wind stress
heat
flu
xes
temperature in the eastern Pacific
Slide 25
Solar forcing of LO-ENSO
forcing solarnoise ~ stress wind )e-Tw(T
A decadal warming is simulated when LO-ENSO is forced with westerly anomalies
Slide 26
)11years
2πtsin(Wforcing solar esterlies
temperature in the eastern Pacific
Months
Simulated Pacific warming in solar maximaIdealized simulationsModel setup as CENS3x sinusoidal solar cycle11 solar cycles, 9 ensembles
Bal et al., 2011 simulationsEGMAM2.5x sinusoidal solar cycle3 ensembles, 10 solar cycles Idealized solar forcing
Slide 27
Top-Down or Bottom-Up?Lagged regression coefficients (25S-25N)
(K/100 sfu)
Tropospheric response lags the stratospheric response by 1-2 years
Slide 28
Summary 2
How does the 11-yr solar cycle affect the tropical oceans?The coupled ensemble shows a basin-wide warming with increased solar cycle forcing. Tempo is given by the westerly anomalies over the tropical Pacific.Both the surface and the tropospheric temperature response lags the solar forcing by ~1-2 years
Slide 29
Outline
1) Introduction2) Model description and analysis methodology3) The response of the tropical lower stratosphere (TLS) to
the SC in ensemble simulations4) The response of the tropical Pacific to the SC in
ensemble simulations5) Synthesis
Slide 30
Troposphere
Stratosphere
Ocean
Stratosphere
Synthesis
1) The tropical Pacific warms in solar maxima.
2) The surface response affects the troposphere but not the stratosphere.
3) Trivial changes in the tropical troposphere by solar signals in the stratosphere.
30°S 30°N
Ocean
Strong
Weak Weak
Not tested
Thank you
Slide 31