1. The Role of the sun in Atmosphere-Ocean coupling
by Indrani Roy
Atmosphere-Ocean coupling (only Pacific)

2. Summary
Overview of Solar influence on climate in a form of flow chart.
Description: Three major variability; viz. solar, QBO and ENSO with oval outlines; major circulations, responsible for modulating the effect shown by non-rectangular parallelograms.
Pathways of signals marked by ‘A’ – ‘Z’; direction of change in behaviour by ‘+’ (for increase) or ‘-’ (for decrease).
Subscripts indicate steps of same process; Superscripts same
effect but different forcing - radiative or dynamical.
Main Points:
Holistic Representation: An overview how atmosphere and ocean is
influenced by solar variability.
How it is disturbed during last half of 20th century.
Why true quantification of solar signal is so difficult.

3. Few points on solar climate relationship
The Sun is principal source of energy in the earth- causes day/night and seasons- reasons to believe solar variability can influence climate.
11 year solar variability is important one as it can be used for prediction purpose.
In terms of energy output only .1 % change from max to min years of 11 year cycle – too negligible to influence climate.
Why regionally different? Some region significant and also depends on time period. Unless any mechanism to support it can be coincidence.
Holistic representation of solar 11 year cycle on climate

4. Outline Background Troposphere - Stratosphere Coupling Role of Sun
Role of Sun +QBO
Atmosphere - Ocean Coupling
Role of Sun+QBO+ENSO
Role of Sun+QBO+ENSO+Climate change
Summary

5. Background: Climatology - SLP[

6. Climatology: SST
[ ]

7. General Circulation [
As SST is always warmer in tropics, general circulation plays role to
transport heat from tropics to pole.
Three North South cells [Hadley cell, Polar cell (both thermally driven)
and Ferrel cell] and jet in between mainly responsible.
Midlattitude Ferrel cell via major eddies transport heat poleward.

8. Background: Stratosphere-troposphere coupling
Charney Drazen Criteria:
stationary waves propagate
only if:
Winter
Northern Hemisphere
Westerlies
in mid to high latitudes
1. Background flow is W ly
and not too strong
In mid-latitudes orography
and land-sea temperature
contrasts generate long
Rossby waves in troposphere.
and 2. Long waves
(wave no. 1 or 2)

9. Schematic Representation
Zero wind line
Meridional temperature
gradient sets up westerly jet in
winter stratosphere
Planetary–scale waves (PW)
propagate upwards under W ly
flow in winter hemisphere
PWs grow and break:
decelerating westerlies
and warming pole.
PW propagation is sensitive to:
Strength of westerlies – Solar influence
Location of zero wind line- QBO influence
(CIRA climatology, Fleming et al., 1990) 9

10. Role of zero wind line : QBO influence
Mechanism:
Holton-Tan Effect:
QBO Ely - warmer pole
1. During E-ly QBO,
zero-wind line moves
to subtropics of the
winter hemisphere
2. It narrows width of
planetary wave-guide
Planetary waves
redirected polewards
4. When such wave events
with large amplitude
break or dissipate they warm
polar stratosphere.
zonal mean wind differences
[Baldwin et al., 2001]

11. Multiple Regression Analysis
SSN 11

12. Sun via Lower stratosphere (C-F)
Atmosphere only
Sun via Lower stratosphere (C-F)
Warming
tropical lower
stratosphere C D
(-)
Δ Hadley cell
Δ Solar
(Decadal) E
(-)
Δ Ferrel cell F
Pole-ward shift &
weakening of STJ
C: Haigh (1996), Gray and Frame (2010)
D, E, F: Haigh (2005, 2006), Brönnimann (2006)

13. Observational (C): Gray and Frame (2010)
Observational (D,E,F): Haigh
Model (D,E,F): Haigh

14. Cloud free Midlatitude
Atmosphere only: Sun via Lower stratosphere
and mid-latitude of Pacific (C-H)
Cloud free Midlatitude
of Pacific
ΔTrade wind
(DJF)
(+) C1 D1 C
Warming
tropical lower
stratosphere D H
Δ Hadley cell
(-)
Δ Solar
(Decadal) E
Δ Ferrel cell
Influence AL and
PH (DJF)
(-) G F
Pole-ward shift &
weakening of STJ
G: Christoforou and Hameed (1997);
H, G: Our result (Regression)
C1, D1: Meehl et al (2008)

15. Aleutian Low(AL) and Pacific High (PH)
Christoforou and Hameed, 1997 (G)
Result Solar (H,G) : Regression (DJF)

16. ‘Bottom up’ Mechanism: Meehl et al , 2008 (C1, D1)
‘Bottom up’ suggests :
More solar radiation through cloud free mid-latitude of pacific in active solar years.
Increased latent heat flux, increased moisture convergence –strengthen trade wind.

17. Atmosphere only: Sun and Polar vortex (A, I-K)
Δ Solar
(Decadal)
Δ Polar
Vortex
(+) A
A, I : Usual mechanism following
thermal wind balance I
J, K : Baldwin (2005);
Our result (Regression)
Intensification
of PJ
(+) J
Δ AAO
Δ AO
(+) K

18. Annular Modes pattern similar (J,K)- Baldwin and Dunkerton (2005)
NAM at 1000 hPa and 10 hPa for Nov-Apr ,

19. Regression : Solar signal in polar modes (J,K)
SSN(JJA)
SSN (Annually)
Both AO and AAO signal is seen during
AAO signal is seen in JJA even for whole 150 yr period ( )
Using different TSI, the result is similar for solar cycle variability

20. Atmosphere only: Sun, polar vortex and lower stratosphere
B: Kodera and Kuroda (2002)
B (B.D.Circulation)

21. Solar influence: Polar vortex and lower stratosphere (B)
Solar UV at 205 nm
increases ~6% from
solar min to solar max
More ozone heating
in upper stratosphere
alters temperature
and wind structure
Solar heating anomalies
also change the strength
of polar stratospheric jet (U)
This influences the path of
upward propagating planetary
waves which deposit their zonal
momentum on the poleward
side of the jet.
(Fig: Kodera and Kuroda, 2002)

22. Stratosphere-Troposphere Coupling: Sun+QBO (A-M)
(Quasi-biannual
Oscillation)
L (-)
M (-)
L, M: our result (Regression,
Roy & Haigh, 2011)

23. Sun, QBO and Polar temperature in north pole Composites of time height
development of NAM
[Labitzke and van Loon, 1992]
[Baldwin and Dunkerton, 2001]
E ly/ Sol Min
Warm
W ly/ Sol Max
Warm
W ly/Sol Min
Cold
E ly/ Sol Max
Cold
W-ly QBO/ Solar min coldest
E-ly QBO/ Solar max also cold
Perturbation in polar stratosphere can affect troposphere for next few months

24. Regression of SLP with Solar*QBO(50 hPa): L,M
Sun, QBO and Atmosphere
Regression of SLP with Solar*QBO(50 hPa): L,M
-ve AO
-ve AAO
Active sun-westerly QBO and less active sun-easterly QBO both
trigger negative AO and AAO features

25. Ocean Coupling (Pacific)
Global ocean Conveyor belt:
Connect mid-latitude of Pacific to tropics
(+)
Thermocline
shifting O1 Q
Δ ENSO
(inter-annual)
(-)
Shallow
MOC
(+)
N. Pacific
warming
(+) P [
Walker circulation
Cold Event of ENSO [ [

26. Niño SST and Thermocline slope interconnected[
Volume transport convergence and SST averaged over eastern tropical Pacific
[Zhang et. al. 2006]

27. Atmosphere-Ocean (Pacific) Coupling: Sun+QBO+ENSO (A-S)
Cloud free Midlatitude
of Pacific N
(+)
Thermocline
shifting
ΔTrade wind
(DJF)
(+) C1 D1
Warming
tropical lower
stratosphere H C C D O1 Q
Δ Hadley cell
(-)
(B.D. Circulation) B
Δ Walker cell
Δ ENSO
(inter-annual) O2
(-)
Shallow
MOC
(+)
Δ Solar
(Decadal)
(+)
Δ Polar
Vortex
(+)
(B.D. Circulation) A R E
(-)
Δ Ferrel cell
Influence AL and
PH (DJF) G1
N. Pacific
warming
(+) P F G2 I
Pole-ward shift &
weakening of STJ S
Intensification
of PJ
N, O2: Usual ENSO mechanism
S: Carvalho et al., 2005 L
(-)
(+) J
Δ AAO
R: Camp and Tung (2007),
Thompson and Baldwin (2001) +
(-)
Δ AO
(+) M K
Δ QBO
(Quasi-biannual)
G2: Our result (Regression)

28. ENSO and JET : Carvalho et al., 2005 (S)
Zonal wind (200 hPa)
Negative AAO phase
Positive AAO phase
Negative-Positive
Cold ENSO are linked with dominant positive AAO and vice versa
AAO phases are allied with latitudinal migration of STJ and intensity
of mid-latitude polar jet

29. Polar vortex and ENSO (R) : Thompson and Baldwin (2001)
(Weak-strong vortex)
Regression : Mid-latitude warming (G2)

30. Nature of ENSO was different before 1950s (and after 1997)
Strong decrease in strength of shallow meridional overturning circulation (MOC) around tropical Pacific after 1950s
Modest intensification since 1998
Also true for Walker and Hadley circulation; more in Walker (McPhaden and Zhang,2004;Vecchi and Soden 2007)
( ) & ( )
( )
SunSpot Number
SunSpot Number
ENSO (DJF)
ENSO (DJF)
Could change in ocean and atmosphere circulation due to climate change during that period have modified the solar- ENSO behaviour?

31. Atmosphere-Ocean Coupling: Sun+QBO+ENSO+Climate change (A-Z)
Cloud free Midlatitude
of Pacific N
(+)
ΔTrade wind
(DJF)
(+)
Thermocline
shifting
(-) C1 D1 X
Climate Change
(2nd half of 20th century)
Warming
tropical lower
stratosphere H C D V2 O1 W Q
(-) T
Δ Hadley cell
(-) U
(B.D. Circulation)
(-) V1 B
Δ Walker cell
Δ ENSO
(inter-annual)
(-)
(+)
(-)
Shallow
MOC
(+) O2
Δ Solar
(Decadal)
(+)
Δ Polar
Vortex
(+)
(B.D. Circulation) A R E
(-) Z Y
Δ Ferrel cell
Influence AL and
PH (DJF) G1
N. Pacific
warming
(+) G2 P F I
Pole-ward shift &
weakening of STJ S
Intensification
of PJ
U, T, W : (McPhaden and Zhang,2004;
Vecchi, et al. 2007) L
(-)
(+) J
Δ AAO
V1, V2 : Usual ENSO mechanism +
(-)
Δ AO
(+) M K
V1 : Our result (Regress., Roy-Haigh 2012)
Δ QBO
(Quasi-biannual)
X, Z : Our result (Regression, do)

32. Solar Signal was different during 1958-1997 (X,Z,V1)
(DJF)
(DJF)
We are
interested
No solar signal is seen around ITCZ of eastern Pacific during later period
Signal around AL weakened

33. Solar Signal on Tropical Pacific SST during 1958-1997(V1)
Regression (SSN) for SST
White et al. (1997)
Warming in tropical E. Pacific after 1950s, follows White et al, (1997)
But ..
No signal when ENSO is included in regression.
Also suggests White et al (1997) may not be true in earlier period.

34. Solar signal during 1958-1997 is also different in polar modes
SSN ( )
SSN ( )
Pathways R and S may be potential route to influence polar modes.
Using different Total Solar Irradiance (TSI), the result is similar.

35. Atmosphere-Ocean coupling (only Pacific)
Next: In holistic representation include
NAO and Indian summer monsoon
Atlantic and Indian Ocean

36. Summary Main Points: Discussed how sun is affecting troposphere.
The effect is different in poles, if QBO is included.
How ocean and atmosphere are connected.
Active sun can influence SST in tropical Pacific though overwhelmed by strong influence of ENSO at LS period.
Main Points:
Proposed an overview how atmosphere and ocean might be affected by solar variability.
How the effect is disturbed during last half of 20th century.
Why true quantification of solar signal is so difficult.

37. Interested in Details
Roy, I., 2013, ‘The role of the sun in atmosphere-ocean coupling’, International Journal of Climatology, doi: /joc.3713.

38. Atmosphere-Ocean coupling (only Pacific)

39. The role of the sun in Atmosphere-Ocean Coupling
Indrani Roy