Solar Spectral Irradiance (SSI) changes, atmospheric effects?

J. Fontenla

NorthWest Research Associatesand

LASP-University of Colorado

The topic: SSI changes, and does it matter?

• Solar Physics issues:– Solar atmosphere structure and SSI– Non-LTE radiative transfer– Solar magnetic (sunspot) cycle– Magnetic effects on the solar atmospheric layers

• Atmospheric issues:– Photochemistry– Heating of various layers of the Earth atmosphere– Ocean currents and energy transport– Effects of all the above on circulation

The solar research on SSI modeling • Emitted intensity spectrum =>solar atmospheres• 1970s: HSRA, BCA, Gingerich, Peytremann, Holweger & Muller• Avrett et al. 1981 VAL non-LTE, Athay & Thomas non-LTE and

chromosphere, Mihalas, Kurucz LTE stellar models, 1980s• Transition region and Lyα, Fontenla et al. 1993 FAL, 1990s

• Solar atmospheres => SSI calculations• Solanki/Unruh 1998, 3 component, LTE• RISE models 1999, 6 components, full/approx NLTE• Shapiro/Krivova 2011, full NLTE in few species/levels• SRPM models 2011, 9 components, resolved over the disk, full

NLTE in 50 species/over 13,000 levels/over 170,000 atomic/ionic lines and over 550,000 molecular lines (LTE).

SSI spectral features and atmospheric regions

Photosphere: visible,IR continuum and weak absorption lines

Lower chromosphere: NUV, visible, IR absorption lines

Upper chromosphere: deep absorption line cores and UV emission lines

Transition region: EUV/FUV emission lines

Fontenla, Avrett, & Loeser 1991, FAL 2, The Astrophysical Journal, 377:712-725

Solar Surface Features

A-weak internetwork (new)B-internetwork (changed C)D-network (new)E-active network (changed F)H-normal plage (new)

P-bright plage (changed P)Q-very hot plage (new)S-sunspot umbra (temp)R-sunspot penumbra (new/temp)

Models of solar atmospheric features

105 1044000

5000

6000

7000

8000

9000

Feature C model 1001 Feature H model 1004 Feature P model 1005

Te

mp

era

ture

(K

)

Pressure (dyne cm-2)

Fontenla et al. 2011, JGR, 116, full NLTE, Tmin very different

Fontenla et al. 2006,The Astrophysical Journal, 639:441–458,Models cross at ~6500 K, in NLTE.

Solanki & Unruh 1998, Astron. Astrophys. 329, 747-753, LTE.No crossing in these models, SSI computed in LTE from FAL P with modifications.

Fontenla et al. 2011, JGR, 116, D20108

0 40 80 120 160 200 240

0.4

0.8

1.2

1.6

2.0

2.4

2.8

3.2 CA CB CD CF CH CP CQ

Te

mp

era

ture

(M

K)

Height (Mm)

Contributions to Quiet-Sun TSI (1360 W m-2):•Photosphere: ~1351 W m-2

•Chromosphere: ~8 W m-2 (power >> TSI observed changes)•Corona+Transition-region: ~70 mW m-2

Transition-region and Coronal layersPhotospheric and chromospheric layers

Computed vs observed SSI

Some observations considered for SRPM set of atmospheric models

Topka et al. 1997, The Astrophysical Journal, 484:479-486

Sanchez Cuberes et al. 2002, The Astrophysical Journal, 570:886–899

Features continuum contrast varies with wavelength and heliocentric angle, corresponds to the slope of T vs p, SRPM model set used detailed radiance observations

San Fernando ObservatoryGround-based radiance observations confirm that ARs are dim in the visible,

over the solar cycle plage near the limb do not increase the visible SSI.

Preminger et al. 2011, ApJ

Ca II K

Red

Blue

Controversy1: Calculated SSI behaviorSolanki & Unruh 1998,Astron. Astrophys. 329, 747-753

According to this paper: «The dotted curve shows the observed relative irradiance variation for λ < 400 nm between solar activity minimum and maximum vs. wavelength, compiled by Lean et al. (1997) and extrapolated to longer wavelengths by Lean (1991). »

100 1000 100001E-5

1E-4

1E-3

0.01

0.1

corr nocorr - corr - nocorr nrlssi - nrlssi

SS

I/SS

I

Wavelength (nm)

Relative changes between Solar Cycle 23 peak/min that I am using for WACCM4 simulation runs.Nocorr – Fontenla et al 2011, SRPM + PSPT imagesCorr - same as above with a correction to match TSINRLSSI – WACCM4 default.“Lean_1610-2140_ann_c100405”

“nocorr” SSI (wavelength,time)

Lower- and upper-chromospherebright/dark fine structure, 1-D models only a first

approximation to the net medium-resolution

Upper-chromosphere

Lower chromosphereExtension of the granulation structure. Some localized energy dissipation in the walls of downdrafts. Loops and mechanical dissipation

3D Radiation Transport & NLTE

1 103

1 104

1 105

1 106

4000

6000

8000

SRP M 306Stein & NordlundSRP M 306 * 0.95

Height (km)

Temp

eratu

re (K

)

mostlyconvectivetransport

mostly radiativetransport

Pressure (dyne cm^-2)

1 103

1 104

1 105

1 106

0

200

400

SRPM 306Stein & NordlundSRPM 306 + 30 km

Pressure (dyne cm^-2)

Heig

ht (k

m)

Mg I 4572C I 5381 CN band

Computed for photospheric convection simulation snapshotwith data from Stein & Nordlund 2005

800 nm 1200 nm 1600 nm500 nm

Network and its change over the cycle, what is “quiet-Sun”?

1 1.21 10

4

1 103

0.01

0.1

1

Intensity

Rel

ativ

e ar

ea

A B D F H P

low

peak

In the so-called “quiet-Sun”, i.e. locations where no obvious AR are present, the intensity distribution of the network is observed to change with the solar cycle (maybe not strictly in phase with the sunspot index).

Intensity distribution at the disk center

A 1101 1374.60

B 1001 1382.19

D 1002 1388.15

F 1003 1391.44

H 1004 1400.86

P 1005 1419.14

S 1006 265.97

R 1007 1103.82

Q 1008 1428.82

Feature, model, TSIThis has implications for SSI and for TSI.But available images lack reliable absolute calibration. Day to day matching was done with the median.

Time series of solar spectral variability from SORCE/SIM

Controversy2: NUV Observations

Various instruments claiming reliable calibration for long term

Most instruments show variation of about ~50/1000~5% except for SUSIM.Only SUSIM measured one peak, since UARS/SOLSTICE hardware failed in 2000Both SORCE instruments show ~6% variations; their decreasing SSI turned around to increasing as SC 24 started in ~2010, but later data is not shown here.

NUV effects on O3

180 200 220 240 260 280 300 320 340 360 380 4000

2

4

6

8

nocorrcorrnrl

Wavelength (nm)

delta

.Flu

x/F

lux_

min

(%

/100

F10

.7 u

nits

)

Calculations were carried out by Merkel et al (see GRL38, L13802 2011), using SORCE data extrapolated in time. These are done with WACCM3 in static SSI runs.Other authors also made simplified calculations showing important differences.

I am carrying out transient WACCM4 (NCAR Community Earth System Model 1.0.3 ) runs with coupled atmosphere, ocean, land, and ice. O3 is included but so are many other processes.

CESM (WACCM4) for SSI study

• Transient runs 1955-2005 including all observed forcing. Imposing observed QBO.

• SSI: wavelength < 120 nm uses F10.7 proxy

• SSI: 120 nm < wavelength < 100 μm:– “const” uses time independent low activity SSI– “nocorr” from SRPM + PSPT & Meudon images,

repeats SC23 (with stretching) – “corr” same as above but with a correction to

match observed TSI, still under development– “nrlssi” using the default SSI in CESM, from Lean

SSI “nocorr” model of SC23, vs NRLSSI

2000 20051358

1360

1362

SRPMLean

TSI

Year

Irra

dian

ce

X0 1600 6.185 10

3

2000 20051.58

1.581

1.582

1.583

1.584

SRPMLean*0.995

6185.5 nm

Year

Irra

dia

nce

X0 1200 3.592 10

3

2000 200513.01

13.015

13.02

13.025

13.03

SRPMLean*0.995

3592.5 nm

Year

Irra

dia

nce

2000 20051970

1975

1980

1985

1990

SRPMLean*0.978

448.5 nm

Year

Irra

dia

nce

2000 20051040

1045

1050

1055

1060

SRPMLean*0.972

368.5 nm

Year

Irra

dia

nce

2000 20054

5

6

7

8

9

10

SRPMLean

121.5 nm

Year

Irra

dia

nce

2000 20051592

1594

1596

1598

1600

1602

SRPMLean*1.006

648.5 nm

Year

Irra

dia

nce

X0 670 942.5

2000 2005794

795

796

797

SRPMLean*0.97

942.5 nm

Year

Irra

dia

nce

X0 800 1.593 10

3

2000 2005252

252.2

252.4

252.6

252.8

SRPMLean*1.018

1593.5 nm

Year

Irra

dia

nce

mW m-2 nm-1 W m-2

Follow some preliminary results• Only from one complete run of each case, the 3

years near the minimum, over 4 solar cycles were averaged and compared.

• The same was done for and 3 years near the maximum over 4 solar cycles.

• Then, the averages of 12 years near min and 12 years near max were subtracted to show the effect of SSI change.

• The maps shown below are for the DJF season, the JJA patterns are different.

• The zonal means are annual.

• More instances are running to form an ensemble. However, Earth behavior is only one instance.

Preliminary WACCM surface resultsdelta.CLOUDT const

delta.TS const

delta.PS const

delta.CLOUDT nocorr delta.CLOUDT nrlssi

delta.PS nocorr delta.PS nrlssi

delta.TS nocorr delta.TS nrlssi

longitudelatitude

Cloud fraction

Surfacte temperature

Surface pressure

ENSO and “natural” variability issues

1960 1970 1980 1990 20004

2

0

2

4

ENSO 3.4 region (DJF)

Year

delta

.T (

K)

Volcanic eruptions are a big issue:Mt. St. Helens 1980El Chichon 1982Pinatubo 1991

1960 1970 1980 1990 2000

5

0

5

10

constcorr*nocorrnrlssi

ENSO SOI

Year

delta

.PS

(hP

a)

Does the SSI choice affect these?More “realizations” are neededHow to cancel volcanic effects?

(DJF)

1960 1970 1980 1990 2000300

200

100

0

100

constcorr*nocorrnrlssi

Alleutian Pressure (DJF)

Year

delt

a.P

S (

hPa)

Zonal mean T and H2O changes

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-0.02000-0.01600-0.01200-0.008000-0.0040000.0000.0040000.0080000.012000.016000.02000

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-0.02000

-0.01600

-0.01200

-0.008000

-0.004000

0.000

0.004000

0.008000

0.01200

0.01600

0.02000

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-0.02000-0.01600-0.01200-0.008000-0.0040000.0000.0040000.0080000.012000.016000.02000

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-2.000-1.600-1.200-0.8000-0.40000.0000.40000.80001.2001.6002.000

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-2.000-1.600-1.200-0.8000-0.40000.0000.40000.80001.2001.6002.000

const nocorr

-80 -60 -40 -20 0 20 40 60 803

2

1

0

-1

-2

-3

Latitude

Lo

g1

0(p

ress

ure

)

-2.000-1.600-1.200-0.8000-0.40000.0000.40000.80001.2001.6002.000

nocorr-const

H2O(relat)

T (K)

“const” displays changes that are not due to the SSI choice, difference of difference can eliminate some but is affected by the “noise” in both “nocorr” and const”

Issues analyzing simulation results to separate SSI effects from other effects

tropical (±25 deg) annual differences between peak and min years

-4 -2 0 2200

300

T (

K)

Log10(pressure)

-4 -2 0 2

0

2

4

de

lta.T

(K

)

Log10(pressure)

T nocorr const nocorr-const

-4 -2 0 20

2

4

6

8

10

12

14

O3

(p

pm

)

Log10(pressure)

-4 -2 0 2-2

0

2

4

6

8

10

12

de

ltare

l.O3

(%

)

Log10(pressure)

O3 nocorr const nocorr-const

-4 -2 0 2

0.1

1

10

100

1000

10000

H2

O (

pp

m)

Log10(pressure)

-4 -2 0 2

-2

0

2

4

De

lta.H

2O

Log10(pressure)

H2O nocorr const nocorr-const

tropos

stratos

mesos

thermos

Other WACCM Simulation Interesting Results

The NRLSSI dif. of dif. have also some of this behavior on the Pacific Ocean Warm Pool but the details are quite different. Also, NRLSSI results show several differences in other regions, e.g. the patterns in Mexico Pacific area, Brasil Atlantic, and Madagascar Indian Ocean which are not shown by “nocorr” results

= DifDif.FSDSShows the downwelling solar shortwave flux at the surface increases of ~30 W m-2 at the Pacific Ocean Warm Pool region at solar max times. But was shown before that the surface temperature does not increase much there. Ocean effects, Kuroshio stream, moderate T?

Nocorr-Const

NRLSSI-Const

Ocean gyres

Ocean currents couple to atmospheric winds and tropospheric energy transport. This is represented in CESM1.0.3/WACCM4 by the integration of the atmospheric model (CAM2) with the deep ocean model (POP).

The tropospheric and ocean phenomena are very tangled!

Analysis is very complex but these simulations contain a wealth of data which could nail down the physical processes induced by SSI changes.That is, if one could also figure out other forcing and variability.

Future work• All the maps shown above is for DJF season, similar ones for JJA

season were done.

• Still improving “corr” SSI case by reprocessing images into “corr2”, hope to have it by end of year 2012 .

• Performing runs for more instances of all SRPM cases, necessary to separate natural variability and SSI effects 4 instances are the target.

• Analysis of the data for ocean and other components of CESM model remains to be done.

• Comparison between CESM 1.0.3 and MODTRAN@ atmospheric radiative heating/cooling to be carried out to evaluate spectral model and resolution effects.

• FUV/EUV SSI ongoing modeling for replacing F10.7 proxy and for forecast of thermospheric neutral density and ionization.

Dark active regionsA nice example on 2/3/2007 shows two large magnetic active regions sunspots side-by-side and one is associated with a lot of chromospheric and coronal heating but the other is not showing much heating.

The magnetic flux of the sunspots is not too different but the bright region is bipolar and more complex.