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

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Intra-ensemble variability of the tropical temperature profiles

Slide 13

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

Reexamination: Observed solar cycle signals ?

Misios and Schmidt, in prep.

Slide 20

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