mike lockwood (southampton university & space science and technology department, stfc/rutherford...

Mike Lockwood(Southampton University

& Space Science and Technology Department, STFC/Rutherford Appleton Laboratory )

Open solar flux and irradiance during the current “exceptional” solar minimum:

implications for climate change

MIST/UKSP Session, RAS/NAM - EAS/JENAM, UoH, 22 April 2009

RecentData

► radial IMF, |Br|

► sunspot number, R

► Kp geomagnetic index

► PMOD composite of TSI

RecentData

► radial IMF, |Br|

► sunspot number, R

► Kp geomagnetic index

► PMOD composite of TSI

Space AgeData

The “Ulysses Result”

ecliptic

Br(r1)

r1

r

|Br|

Balogh et al., 1995; Lockwood et al., 1999; 2004 Smith et al., 2001

Lockwood and Owens (2009) & Lockwood et al.

(2004) show that use of this equation is accurate to

within 2.5%

Thus total signed magnetic flux threading r1 = 1AU is

FS(r1) = (1/2)4r12 <|Br(r1)|>CR

Ulysses showed that|Br(r)| (r/r1)2 = |Br(r1)|

Open Solar Flux from IMF data (Lockwood, Rouillard and Finch 2009)

1970 1980 1990 2000 2010

7

6

5

4

3

2

1

Ope

n S

olar

Flu

x, F

S (

1014

Wb)

FS(r1)► using the

Ulysses result of the invariance of the radial IMF, Br & hourly mean data

► accurate to 2.5%

Open Solar Flux

ecliptic

Coronal Source Surface

quantified by PFSS from solar magnetograms

Br(r1)r1

r

|Br|

Balogh et al., 1995; Lockwood et al., 1999; Smith et al., 2001

total (“open”) magnetic flux leaving the sun, FS(ro) =

(1/2)x42 ro2<|Br(ro)|>CR

“excess”, FS(r) FS(ro) > 0

ro

Kinematic Excess Flux Correction (Owens et al. 2008, Lockwood et al. 2009)

► excess flux,

FS(r) =

2r2|Br(r)|

2r12|Br(r1)|

► ro = 2.5R

► PFSS values from photospheric magnetograms

FS(r1) = 0

FS(ro), from PFSS

Open Solar Flux from IMF data (Lockwood, Rouillard and Finch 2009)

1970 1980 1990 2000 2010

7

6

5

4

3

2

1

Ope

n S

olar

Flu

x, F

S (

1014

Wb)

► kinematic correction for effect of longitudinal solar wind structure, FS(ro)

► makes results consistent with PFSS

(Lockwood et al., 2009)

FS(ro) = FS(r1) FS(ro)

[ FS(ro) ]PFSS

FS(r1)

► sunspot number, R

► open solar flux FS

► GCR counts C

► observations of TSI

► solar cycle length, L

running mean over T=[9:(1/4):13] yrs

running mean over T=L yrs

► global mean temperature

The current minimum follows from recent trends. (Lockwood and Fröhlich, 2007)

Millennial Variation composite 25-year means) from cosmogenic isotopes 14C & 10Be by Steinhilber et al. (2008)

Year AD

Solar Modulation Parameter, (MV)

-6000 -4000 -2000 0 2000

1000

800

600

400

200

0

composite from Solanki et al., 2004; Vonmoos et al., 2006 & Muscheler et al., 2007

we are still within recent grand maximum

show the present minimum 23/24 is close to minima 19/20 and 16/17

earlier minima are lower

Cenntennial Variations- Geomagnetic Activity Indices

Geomagnetic activity annual means: correlations with solar wind & IMF

the corrected aa index is a range index & correlates best with BIMFVSW

2

the median index m is from hourly mean data & correlates best with BIMFVSW

0.3

aaC m

raa = 0.97Sr > 99.999% (AR-1 noise)

rm = 0.89 Sr = 99.995%(AR-1 noise)

Centennial Variationsgeomagnetic activity

the different dependences of aaC and m on VSW are significant at the 87% level.

0.87

Centennial Variations:reconstructed solar wind, IMF & open flux

use correlations to extrapolate VSW, BIMF & FS annual means back to 1905

Centennial Variations: the rise and fall of the current grand maximum

solar cycle running means

Abreu et al. (2008)

defining grand max. by > 600 MV it began in 1920 linear extrapolation gives end dates consistent with GSM durations

Has The Temperature Rise at Earth’s Surface Stalled in Recent Years?

Global Mean Air Surface Temperature (GMAST) composite from CRU, UEA

HadCRUR3v

/2

time constant used to smooth data = 10 years

Has The Temperature Rise at Earth’s Surface Stalled in Recent Years?

3 example trends for the last /2 years:2 per 100yr0 per 100yr

+2 per 100yr

Variations about the trend

= 10 yr

for the last /2 years:

2 per 100yr

Variations about the trend

= 10 yr

for the last /2 years:

0 per 100yr

Variations about the trend

= 10 yr

for the last /2 years:

+2 per 100yr

Compare to the distribution of past variations about the trend

Distribution of deviations over /2 yrs

= 10 yrs

3 example trends for the last /2 years:2 per 100yr 0 per 100yr+2 per 100yr

= 10 yrs<x> = 0.001x = 0.034

Recent (last /2 yrs) fluctuations pdf:-

Recent (last /2 yrs) fluctuations are consistent with past ones around a trend of +2c-1

For = 6 yr recent trend is most probably -2c-1 (but could be up to +4c-1)

For > 10 yr trend is most likely > 0

For > 18 trend +2c-1

► the present solar minimum is uniquely the present solar minimum is uniquely low - for the space agelow - for the space age► cosmogenic isotopes show that the cosmogenic isotopes show that the space age thus far has been a grand solar space age thus far has been a grand solar maximum (GSM)maximum (GSM)► geomagnetic activity data and the geomagnetic activity data and the statistics of GSM durations both indicate statistics of GSM durations both indicate that the present low minimum is consistent that the present low minimum is consistent with the end of the current GSMwith the end of the current GSM► the levelling off of global mean air surface the levelling off of global mean air surface temperatures is consistent with previous temperatures is consistent with previous fluctuations about the upward trend fluctuations about the upward trend