Usingtropicalarchivesofprecipitationisotopic ...crlmd/these/presentation_CRisi_AGUdec2011.pdf ·...

Using tropical archives of precipitation isotopic

composition to assess the credibility of projected

changes in precipitation

Camille Risi

LMD/IPSL/CNRS (Paris, France)

with the contribution of: S. Bony, F. Vimeux, R. Eagle, A. Tripati

AGU: 6 December 2011

Spread in precipitation projections

precipitation change

by 2100 (%)

<2/3 agree on sign

IPCC AR4

2/10



by 2100 (%)

<2/3 agree on sign

IPCC AR4

◮ Can we assess the credibility of future precip projections oftropical precip using past changes?

2/10



by 2100 (%)

<2/3 agree on sign

IPCC AR4


1. if a model is better for the past, is it better for the future?only if common mechanisms

2/10



by 2100 (%)

<2/3 agree on sign

IPCC AR4


1. if a model is better for the past, is it better for the future?only if common mechanisms

2. if robust proxy for past precip changes:δ18O (ice cores, speleothems...)?

2/10

1) Past/future precipitation changes

◮ 11 climates using LMDZ GCM forced by SST anomalies

2xCO2 MIROChi 2xCO2 ECHAM2xCO2 IPSL4xCO2 IPSLpresent−day

ITC

Z l

atit

ude

(°N

)

shift to North annual, zonal mean

shiftto

Southwarmer North

Eemien IPS THC+

MH IPSLEemien IPSL

LGM IPSL THCoffLGM IPSLLGM climapClimates:

SST gradient (K)(30N−10N − 30S−10S)

cooler Northwarmer South

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2-1.5-1-0.500.511.5

3/10



−1

−0.5

0

0.5

1

1.5

2


ITC

Z l

atit

ude

(°N

)


shiftto

Southwarmer North

Sensitivity tests

Eemien IPS THC+

MH IPSLEemien IPSL


less condensationmore detrainment




ITC

Z l

atit

ude

(°N

)

less diffusioncontrole

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2-1.5-1-0.500.511.5

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

◮ precipitation response depends strongly on the physics

3/10



−1

−0.5

0

0.5

1

1.5

2


ITC

Z l

atit

ude

(°N

)


shiftto

Southwarmer North

Sensitivity tests

Eemien IPS THC+

MH IPSLEemien IPSL


less condensationmore detrainment




ITC

Z l

atit

ude

(°N

)

less diffusioncontrole

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2-1.5-1-0.500.511.5

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

◮ precipitation response depends strongly on the physics◮ work in progress: regional scale over land? 3/10

2) What controls δ18O in the tropics?

◮ the amount effect: precipր=⇒ δ ց (Dansgaard 1964)

4/10


◮ the amount effect: precipր=⇒ δ ց (Dansgaard 1964)◮ obs+modelling (Risi et al 2008 JGR,GRL, 2010 JGRb,QJRMS)

4/10



Rayleigh distillation

In mid/high latitudes:

4/10



In the tropics:

clear−skysubsidence

convective system



4/10



In the tropics:


convective system



unsaturated downdraftsrain evaporation

4/10



In the tropics:


convective system



unsaturated downdraftsrain evaporation

◮ Paleo time scales: precip or temperature (Thompson et al 2000)?

=⇒analysis with LMDZ-iso (Risi et al 2010 JGRa) 4/10

Simulated paleo δ18O: example in Asia

−18

−21

−15

−12

−9

12N

6N

18N

24N

30N

36N

70E 80E 90E 120E110E100E−9

−7

−6−5−4

−3−2

−101

3

LMDZ simulations

data(Thompson et al 1997)

δ18O

(h)Guliya i e ore

( 250x350km)LGM-present, standard simulation∆δ18O (h)

Guliya Hulu avePuxianDundepresent Mid Holo ene LGMAge (ka before 1950)

5/10

Simulated paleo δ18O: example in Asia

70E 80E 90E 120E110E100E

12N

6N

18N

24N

30N

36N

−18

−21

−15

−12

−9

12N

6N

18N

24N

30N

36N

70E 80E 90E 120E110E100E−9

−7

−6−5−4

−3−2

−101

3

LMDZ simulations

data(Thompson et al 1997)

δ18O

(h)Guliya i e ore

( 250x350km)LGM-present, standard simulation LGM-present, zoomed simulation(down to 50km)∆δ18O (h)

Guliya Hulu avePuxianDundepresent Mid Holo ene LGMAge (ka before 1950)

◮ high resolution -> regional circulation changes5/10

Simulated paleo δ18O: South America

−9 −7 −6 −5 −4 −3 −2 −1 0 1 3

40S

30S

20S

10S

Eq

10N

40W60W80W

LGM−present, standard(250 x 350km)

Sajama

Illimani

Huascaran

Botuvera cave

Rio Grande cave

UyuniSantana cave

◮ LGM depletion=long standing problem in GCMs

6/10

Simulated paleo δ18O: South America

−9 −7 −6 −5 −4 −3 −2 −1 0 1 3

40S

30S

20S

10S

Eq

10N

40W60W80W 40W60W80W40S

30S

20S

10S

Eq

10N

LGM−present, zoomedLGM−present, standard(250 x 350km) (down to 50km)

Sajama

Illimani

Huascaran

Botuvera cave

Rio Grande cave

UyuniSantana cave

◮ LGM depletion=long standing problem in GCMs◮ resolution is only part of the problem

6/10

δ18O controls in LMDZ: Asia

15N6N33N24N

50E 60E 70E 80E 90E 100E0.90.70.50.3-0.3-0.5-0.7-0.94xCO2 IPSL2xCO2 IPSL2xCO2 ECHAM2xCO2 MIROChipresent-dayClimates: LGM limapLGM IPSLLGM IPSL THCo�MH IPSLEemien IPSLEemien IPS THC+

-0.2 0 0.2 0.4 0.6 0.8 1-7-6-5-4-3-2-1012

regional ∆P (mm/d)∆δ18O

p

(h)Guliya i e ore

Correlation δ18Op - P

7/10

δ18O controls in LMDZ: Asia

15N6N33N24N

50E 60E 70E 80E 90E 100E0.90.70.50.3-0.3-0.5-0.7-0.94xCO2 IPSL2xCO2 IPSL2xCO2 ECHAM2xCO2 MIROChipresent-dayClimates: LGM limapLGM IPSLLGM IPSL THCo�MH IPSLEemien IPSLEemien IPS THC+

-0.2 0 0.2 0.4 0.6 0.8 1-7-6-5-4-3-2-1012

regional ∆P (mm/d)∆δ18O

p

(h)Guliya i e ore

Correlation δ18Op - P

◮ δ18O =good proxy for past regional precipitation changes7/10

δ18O controls in LMDZ: South America

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

−0.4 −0.2 0 0.2 0.4 0.6 0.8 10.90.70.50.3-0.3-0.5-0.7-0.94xCO2 IPSL2xCO2 IPSL2xCO2 ECHAM2xCO2 MIROChipresent-dayClimates: LGM limapLGM IPSLLGM IPSL THCo�MH IPSLEemien IPSLEemien IPS THC+

70W 50W 30W90W30S20S10SEq10N

Illimani i e ore regional ∆P (mm/d)∆δ18O

p

(h)Correlation δ18Op - P

8/10

δ18O controls in LMDZ: South America

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

−0.4 −0.2 0 0.2 0.4 0.6 0.8 10.90.70.50.3-0.3-0.5-0.7-0.94xCO2 IPSL2xCO2 IPSL2xCO2 ECHAM2xCO2 MIROChipresent-dayClimates: LGM limapLGM IPSLLGM IPSL THCo�MH IPSLEemien IPSLEemien IPS THC+

70W 50W 30W90W30S20S10SEq10N

Illimani i e ore regional ∆P (mm/d)∆δ18O

p

(h)Correlation δ18Op - P

◮ δ18O =good proxy for past regional precipitation changes8/10

Is P-δ18O sensitive to model physics?

−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5

1.5 2 2.5 3 3.5 4 4.5


Eemien IPS THC+

MH IPSLEemien IPSL


Regional pre ipitation (mm/d)

δ18O

(h)Illimani

9/10


−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5

1.5 2 2.5 3 3.5 4 4.5


Eemien IPS THC+

MH IPSLEemien IPSL

LGM IPSL THCoffLGM IPSLLGM climapClimates: Sensitivity tests

less condensationmore detrainmentless diffusivecontrol


δ18O

(h)Illimani

9/10


−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5

1.5 2 2.5 3 3.5 4 4.5 23 24 25 26 27 28 29 30 31−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5


Sensitivity tests


Eemien IPS THC+

MH IPSLEemien IPSL


tropi al mean SST (◦C)δ18O

(h)


δ18O

(h)Illimani

◮ depending on the physics, δ18O controlled by upstream precipor by average temperature

9/10


−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5

1.5 2 2.5 3 3.5 4 4.5 23 24 25 26 27 28 29 30 31−7.5

−7

−6.5

−6

−5.5

−5

−4.5

−4

−3.5


Sensitivity tests


Eemien IPS THC+

MH IPSLEemien IPSL


tropi al mean SST (◦C)δ18O

(h)


δ18O

(h)Illimani

◮ depending on the physics, δ18O controlled by upstream precipor by average temperature

◮ not obvious which one is most realistic 9/10

Conclusion and perspectives

SST changes

precipitation changes

past

precipitation changesfuture

physical

processes

isotopicchanges

10/10


SST changes


past

physical

processes


physical

processes

isotopicchanges

10/10


SST changes


past

physical

processes


physical

processes

isotopicchanges

◮ To go further:

◮ better understand physical processes

10/10


SST changes


past

physical

processes


physical

processes

isotopicchanges

◮ To go further:

◮ better understand physical processes◮ CMIP5: link between physical processes at present, past

changes and future projections (but isotopes missing)

10/10


SST changes


past

physical

processes


physical

processes

isotopicchanges

◮ To go further:

◮ better understand physical processes◮ CMIP5: link between physical processes at present, past

changes and future projections (but isotopes missing)◮ any paleo-data synthesis effort planned for δ18O?

10/10

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