Solar Influence on Surface
Air Temperature During the
Maunder Minimum
J. Feynman, A. Ruzmaikin (JPL, Caltech),
X. Jiang, D. Noone and Y. Yung (Caltech)
Maunder Minimum
1645-1715
20
10
14
∆C
0
-10
-20
-30
1500
1600
1700
1800
year
1900
2000
• MM in cosmic
ray flux.
• Also seen in
aurora &
sunspots
• Mean northern
hemisphere
relative ∆T
about 0.1 ºC
(Mann et al.)
North Annular Mode
•
Pattern of wintertime climate
anomalies with two states, 1) high
pressure at pole and a band of
lower at lower latitudes .2) the other
way round
•
Account for 23% of variability at sea
level
Thompson & Wallace (98)
Baldwin & Dunkerton (99)
Solar Influence on the North
Annular Mode
Stratosphere
10hPa
West QBO
1
1
0
0
-1
-1
1
21
41
61
In early (late) winter
for West (East) QBO
UV effect on NAM is
not damped
between 10hPa and
850hPa
East QBO
81
101
1
21
41
61
81
101
NAM index is
persistently low in
troposphere during
Maunder Minimum
850hPa
Troposphere
1
1
0
0
-1
-1
1
21
41
61
81 101
Days from November 1
1
21
41
61
81 101
Days from November 1
High UV flux - circles, Low UV flux - asterisks
Ruzmaikin &
Feynman(02)
Test of statistical significance
(troposphere)
100
West
QBO
80
60
40
obs
20
0
0
0.1
0.2
0.3
0.4
0.5
max |<NAM>| at 850 hPa, West QBO (m = 0.27, σ = 0.07)
0.6
0.7
0.6
0.7
100
East
QBO
80
60
obs
40
20
0
0
0.1
0.2
0.3
0.4
0.5
max |<NAM>| at 850 hPa, East QBO (m = 0.28, σ = 0.08)
Distribution of
1,000
realizations of
max |< NAM >|
for randomized
data at 850 hPa
Approach
• Tropospheric NAM index is more negative at
solar min than at solar max (R & F, 02)
• Use NCEP data to isolate ∆T pattern due to
NAM (minimize contribution of other EOF
modes)
• Compare with pattern of sensitivity of
temperature to solar forcing (Waple et al.)
Isolate ∆T pattern,due to ∆ NAM
Observed potential height is
PH=∑PCn EOFn
1) Form composite of 10 months when <NAM>
has highest positive values; form Th
composite
m >1
∑PC1 EOF1>> ∑PCm EOFm
2) Repeat for <NAM> most negative,form Ts
3) ∆T = Th minus Ts
NAM Temperature Anomaly
Modern ∆T
Solar Max
Minus Min
Irradiance
Sensitivity
Waple et al. 2002
Conclusion
A major part of the Northern Hemisphere
temperature changes driven by the Sun can be
attributed to effect of solar changes on the NAM
mode of atmospheric variability.
Maunder Minimum NAM
1
0.8
850 hPa
0.6
• Modern maximum
0.4
NAM index
0.2
0
- 0.2
• Maunder minimum
- 0.4
- 0.6
- 0.8
-1
1
21
41
61
Days from November 1
81
101
(using Lean
et al. 1995)