in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere

(1)

L t i bilit f i d t i di lid b d Long term variability of cosmogenic and terrigenous radionuclides observed Long‐term variability of cosmogenic and terrigenous radionuclides observed Long term variability of cosmogenic and terrigenous radionuclides observed g y g g

in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere

Ch i t h El ä (1) Di t W b h (1) I b L i (1) R lf W ll (2) d A t W ll (3) Christoph Elsässer (1) Dietmar Wagenbach (1) Ingeborg Levin (1) Rolf Weller (2) and Anton Wallner (3) Christoph Elsässer (1), Dietmar Wagenbach (1), Ingeborg Levin (1), Rolf Weller (2), and Anton Wallner (3)

(1) Institut für Umweltphysik University of Heidelberg Germany (christoph elsaesser@iup uni heidelberg de) (2) Alfred Wegener Institute for (1) Institut für Umweltphysik, University of Heidelberg, Germany (christoph.elsaesser@iup.uni‐heidelberg.de), (2) Alfred Wegener Institute for Polar and Marine Research Bremerhaven Germany (3) Vienna Environmental Research Accelerator University of Vienna Austria

Polar and Marine Research, Bremerhaven, Germany, (3) Vienna Environmental Research Accelerator, University of Vienna, Austria y ( ) y

1 Background and objective 3 H d th N d fit t th 5 C id tif th i f th

1. Background and objective 3 How do the Neumayer records fit to those 5 Can we identify the main causes for the 1. Background and objective 3. How do the Neumayer records fit to those y 5. Can we identify the main causes for the y

radioisotope variability?

from other Antarctic sites? radioisotope variability?

from other Antarctic sites?

Diff i h i l l

from other Antarctic sites? radioisotope variability?

Different to various chemical aerosol components cosmogenic ⁷Be or ¹⁰Be and components, cosmogenic Be or Be and

210

7 B lit Y !

terrigenous^g ²¹⁰Pb radioisotopes offer relatively^p ^y Coastal: Mean activity levels of ⁷Be and ²¹⁰Pb at

7 Be seasonality: Yes!

^1.4

well known spatio temporal source distributions Coastal: Mean activity levels of Be and Pb at

N b i l hi h d h

Be seasonality: Yes!

well known spatio‐temporal source distributions Neumayer are substantial higher compared to the ⁷_Be/²¹⁰_Pb

S h h h (STE)

on the global scale. As carried by the sub‐micron y g p

(relatively short) records at the more northward Stratosphere‐ troposphere exchange (STE) ^{Be/ Pb} ^{1 2} on the global scale. As carried by the sub micron

l f ti th i t tit t th (relatively short) records at the more northward p p p g ( ) ^1.2

indicated by ⁷Be/²¹⁰Pb and ¹⁰Be/⁷Be point to

aerosol fraction these isotopes constitute thus a sites. indicated by Be/ Pb and Be/ Be point to

unique tracer system for studying the meridional

stronger stratospheric impact during Antarctic unique tracer system for studying the meridional

l A i ll h Inland: Comparison with South Pole the only g p p g ^{1 0}

summer/autumn than during winter/spring

long range transport to Antarctica as well as the Inland: Comparison with South Pole, the only ^1.0

summer/autumn than during winter/spring.

g g p

stratosphere/troposphere air mass exchange other Antarctic site with long‐term ⁷Be and ²¹⁰Pb

stratosphere/troposphere air mass exchange. other Antarctic site with long term Be and Pb

d l d b dl i il l l

210 Pb lit N !

records revealed broadly similar mean levels _{0 8}

Aimed at deploying this approach on a

Fig. 1: Air chemistry observatory at Aimed at deploying this approach on a (though partly disturbed by missing S Pole data)

210 Pb seasonality: No!

^0.8

climatological time scale continuous 25 years Fig. 1: Air chemistry observatory at

N St ti d t d 2008 (though partly disturbed by missing S.Pole data)

Pb seasonality: No!

d l i l h i f ⁷B

10Be/⁷Be

climatological time scale, continuous 25 years Neumayer Station ‐ updated 2008.

l i ib i f d l

and common multi‐annual changes in case of ⁷Be. ^{Be/ Be}

records of these nuclides we obtained at the g Relative contribution of source and long range

records of these nuclides we obtained at the 0.6

t l A t ti N St ti ( tl

g g

transport changes not clear yet Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

coastal Antarctic Neumayer Station (concurrently transport changes not clear, yet. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

with chemical aerosol records) are presented ^2.5 Fig. 8: 25 years averaged seasonal cycles

with chemical aerosol records) are presented. Fig. 8: 25 years averaged seasonal cycles

f ¹⁰B /⁷B d ⁷B /²¹⁰Pb t bli h d

7 Be ¹⁰ Be decadal cycle: Yes !

^of¹⁰^Be/⁷^Be and⁷^Be/²¹⁰Pb established

South Pole Station

7 Be, ¹⁰ Be decadal cycle: Yes !

from detrended data

2 0

South Pole Station

, y

from detrended data.

2.0

2 Long term ariabilit of aerosol borne

^h ^d ^h ^d ^l ^l ^{h (} ⁾

2 Long‐term variability of aerosol‐borne

^• The 9‐11 years periodicity seen in the Be‐isotope records stongly correlates with (Antarctic)

2. Long term variability of aerosol borne

^y ^p ^y ^p ^{g y} ⁽ ⁾

McMurdo neutron monitor data which mainly reflect the change in the cosmic ray flux Fig 5: Overall mean of atmospheric ⁷Be and ^1.5

di lid N S i

Fig. 5: Overall mean of atmospheric Be and McMurdo neutron monitor data which mainly reflect the change in the cosmic ray flux,

210Pb ti iti t N St ti

radionuclides at Neumayer Station

²¹⁰Pb activities at Neumayer Station modulated by decadal solar activity (sun spot) cycle.

radionuclides at Neumayer Station

modulated by decadal solar activity (sun spot) cycle.

• There is no extraordinary phase lag to the solar activity driven production change indicating a compared with those at other Antarctic _{1 0}

y

compared with those at other Antarctic _• There is no extraordinary phase lag to the solar activity‐driven production change, indicating a

( d b )

1.0

merely polar significance of the Be‐isotope signal

sites (US‐EML data base).( ) merely polar significance of the Be isotope signal.

Fi 9 ⁷B d ¹⁰B d d l h

0 5 _{1 2} Fig. 9: ⁷Be and ¹⁰Be decadal changes

Th h i di i d

0.5 _1.2

McMurdo neutron monitor - monthly means

10 The atmospheric radioisotope data at Neumayer Station McMurdo neutron monitor monthly means ^1.1 compared to McMurdo Neutron

8 10

Be

compared to McMurdo Neutron

d f h

p p

Neumayer provide the most comprehensive

Neumayer Station ^1.1

8

Be

monitor data serving as proxy for the

Neumayer provide the most comprehensive _0.0 _1.0 g p y f

cosmic ray flux variability In record of such observations in Antarctica ¹⁹⁷⁰ 1975 1980 1985 1990 1995 2000 2005 2010

0 9 cosmic ray flux variability. In

over the last 27 years moreover including ^0.9

6 over the last 27 years, moreover including Fig 6: Comparison of normalized ⁷Be time series at highlighting the decadal signal, the

0 8

6 Fig. 6: Comparison of normalized Be time series at

h h l l h

highlighting the decadal signal, the atmospheric data are simply filtered by

up to now the only ¹⁰Be atmospheric data. ^1.4 ^0.8

M] Neumayer with South Pole Station along with 0.25 atmospheric data are simply filtered byup to now the only Be atmospheric data.

10B

SC y g

years smoothed lines Note the relatively large _{1 2} ¹⁰^Be 2 and 3 years Gaussian smoothing (to

at/ 4 years smoothed lines. Note the relatively large 2 and 3 years Gaussian smoothing (to

t th di ti l ti f

4 1.2

104

scatter at South Pole. respect the diverse time resolution of

[ scatter at South Pole.

the isotope records) Note that strong

1 0 the isotope records). Note that strong

l d d d

1.0

2 Solar Proton Events periods indicated

2

4 Decoding the information by dedicated

^0.8 ⁷^Be by grey bars are likely to detract from^p

4. Decoding the information by dedicated

^Be by grey bars are likely to detract from

4. Decoding the information by dedicated

the common covariance between both

0

ti i l i

t e co o co a a ce bet ee bot radioisotopes

1990 2000 0.6

0 1983 2007

time series analysis

¹⁹⁸³ 1990 2000 2007 radioisotopes.

1990 2000

1983 2007

time series analysis

Fig 3: Yearly means of atmospheric ¹⁰Be

I t l ill ti f ti t l

Fig. 3: Yearly means of atmospheric ¹⁰Be

y

Interannual oscillations of continental or

(commonly analysed in ice cores as well).

Interannual oscillations of continental or

Fig 2: High‐volume aerosol (commonly analysed in ice cores as well).

stratospheric airmasses: No!

Fig. 2: High volume aerosol

li f ili f N ^{1 2}

stratospheric airmasses: No!

sampling facility of Neumayer^{p g f} ^y ^f ^y ^1.2 In the ⁷Be time series Singular Spectrum

stratospheric airmasses: No!

Station In the Be time series Singular Spectrum

A l i (th M ltiT M th d d W l t

7 1.1

Th i l l t l i l ff t id tifi d th t i bl t d i th b d i t l

Station. Analysis (the MultiTaper Method and Wavelet

200

M]

7Be _{1 0}

There is no local meteorological effect identified that is able to drive the observed interannual Analysis) points to three major signals:

SCM 1.0

changes This suggests long‐range meridional and large‐scale vertical (cross‐tropopause) air Analysis) points to three major signals:

Fi 4 ⁷B ²¹⁰Pb d ⁷B /²¹⁰Pb ti

fCi/S 100 0.9

changes. This suggests long range, meridional and large scale, vertical (cross tropopause) air

b h i l i h l i i bili

Fig. 4: ⁷Be, ²¹⁰Pb and ⁷Be/²¹⁰Pb time

[f 0.8 1.2

mass transport to be the main player in the multi‐year variability.

→ Seasonal cycle series collapsed into monthly

0 2

0.8

1 1

1.2 → Seasonal cycle p p y y y

series collapsed into monthly

0 2

210 1.1

→ ca. 10 years periodicity means and highlighted by

]

210Pb _1.0 → y p y

→ 2 3 years signal

g g y

smoothing Note the conspicuous

Exemplary modelling attempt

1 ^CM

] 2.0 ⁷Be measurements model0 9 → 2‐3 years signalsmoothing. Note the conspicuous

Exemplary modelling attempt

1

Ci/S model0.9

anomaly in 2002 and that the

Exemplary modelling attempt

[fC

?

^1.5^0.8^1.2 _For ²¹⁰Pb again the seasonal cycle is evident

anomaly in 2002 and that the

7Be/²¹⁰Pb ratio is expected a

?

0 1 1 1 0

A prima facie approach based on a 28‐box global For ²¹⁰Pb again the seasonal cycle is evident,

7Be/²¹⁰Pb ratio is expected a

0 300 7

Be/²¹⁰Pb

?

1.1 1.0

A prima facie approach based on a 28‐box global

( )

but here, on top of a 3‐4 years oscillation. The surrogate for the stratospheric air

Be/ Pb

1.0 0 5

atmospheric transport model (Levin et al., 2010) and but here, on top of a 3 4 years oscillation. The

l tt i t i l f i A t ti i l ti surrogate for the stratospheric air

200 i fl ^0.5

0 9 p p ( , )

on Be isotope production rates calculated by latter is typical for various Antarctic circulation

mass influence.

100 ¹⁹⁸³ ¹⁹⁹⁰ ²⁰⁰⁰

2007 1.0 0.9

on Be‐isotope production rates calculated by indices though no statistically robust

100 ¹⁹⁸³ ¹⁹⁹⁰ ²⁰⁰⁰

0 5 0.8 2007

Usoskin and Kovaltsov (2008) was performed, with indices though no statistically robust

h ld b f d

1985 1990 1995 2000 2005 Usoskin and Kovaltsov (2008) was performed, with 0.5

the southern hemisphere STE being calibrated by the coherence could be found.

1990 2000 2007

1983 0 0

Fig. 7: First three components of a (Monteg p f ( the southern hemisphere STE being calibrated by the ^0.0

Carlo) Singular Spectrum Analysis of the ⁷Be Neumayer ¹⁰Be/⁷Be ratio ^{-0 5}

References

Carlo) Singular Spectrum Analysis of the ⁷Be Neumayer Be/ Be ratio.

resid als

References

data set. While the seasonal and 10 years -0.5

d l b d l d d b d ⁷

residuals

References

data set. While the seasonal and 10 years -1 0

i l l l i ifi t th 2 3 → Residuals between modeled and observed ⁷Be ¹⁹⁸³ ¹⁹⁹⁰ ²⁰⁰⁰ ²⁰⁰⁷ ^1.0

signals are clearly significant, the 2‐3 years

variability confirm upper qualitative findings on the

Koch, D.M., and M.E. Mann (1996), Spatial and temporal variability of 7Be surface concentrations, Tellus, 48B, 387‐396.

Fig. 10: Model based reconstruction of

one remains ambiguous variability confirm upper qualitative findings on the

Koch, D.M., and M.E. Mann (1996), Spatial and temporal variability of 7Be surface concentrations, Tellus, 48B, 387 396.

Levin I Naegler T Kromer B Diehl M Francey R J Gomez Pelaez A J Steele L P Wagenbach D Weller R Fig. 10: Model based reconstruction of

th t A t ti ⁷B ti i

one remains ambiguous.

seasonality and production signal. Again, a 2‐3

Levin, I., Naegler, T, Kromer, B., Diehl, M., Francey, R.J., Gomez‐Pelaez, A.J., Steele, L.P., Wagenbach, D., Weller, R.,

W th D E (2010) Ob ti d d lli f th l b l di t ib ti d l t t d f t h i ¹⁴CO seasonality and production signal. Again, a 3 the recent Antarctic ⁷Be time series

years signal remains in residual time series

Worthy, D.E. (2010), Observations and modelling of the global distribution and long‐term trend of atmospheric ¹⁴CO₂,

compared to normalized ⁷Be years signal remains in residual time series,

T bl E l i d i f diff i l

Tellus, 62B(1), 26‐46. compared to normalized Be

b i N i l

indicating, among others, a realistic simulation of Table: Explained variances of different signals

( )

Usoskin, I.G., and G. A. Kovaltsov (2008), Production of cosmogenic ⁷Be isotpe in the atmosphere: Full 3‐D modeling, J.

observations at Neumayer station, along indicating, among others, a realistic simulation of

th l (t t l t d) d th 11

p f ff g

detected in the ⁷Be data of South Pole (Koch

Usoskin, I.G., and G. A. Kovaltsov (2008), Production of cosmogenic Be isotpe in the atmosphere: Full 3 D modeling, J.

Geophys Res 113 D12107 y g

with model observation residuals the seasonal (transport related) and the 11 years

detected in the Be data of South Pole (Koch

Geophys. Res., 113, D12107.

N i f h B l R h I i d b NSF ATM 0527878 with model‐observation residuals

solar (source related) cycles and Mann, 1996) and Neumayer Station.

Neutron monitors of the Bartol Research Institute are supported by NSF grant ATM‐0527878.

highlighted by a 0.5 year smoothing.

solar (source related) cycles.

, ) y

g g y y g

in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere in the coastal Antarctic troposphere

L t i bilit f i d t i di lid b d Long term variability of cosmogenic and terrigenous radionuclides observed Long‐term variability of cosmogenic and terrigenous radionuclides observed Long term variability of cosmogenic and terrigenous radionuclides observed g y g g