Climate response associated with the Southern Annular Mode in the surroundings of Antarctic Peninsula Andrea F. Carril, Claudio G. Menéndez and Antonio

Climate response associated with the Climate response associated with the Southern Annular Mode in the Southern Annular Mode in the

surroundings of Antarctic Peninsulasurroundings of Antarctic Peninsula

Andrea F. Carril, Claudio G. Menéndez and Antonio Navarra


Images are courtesy of the National Snow and Ice Data Center (NSIDIC), University of Colorado

Spatial trends of the Antarctic Sea-Ice Concentration

Monthly Antarctic sea-ice drifts derived from the SMMR/SSMI over 1979-2000 (Lui et al. 2004)


• Contours are trends [%]

• Left: full trends

• Right: trends after removing SAM and ENSO

(contours give the trends due to SAM and ENSO)

Observed SAM-related variability in SIC

Regression between seasonal SAM index and SIC (HadISST1), JAS, 1980-1999 (Lefebvre et al. 2004)


• Shadows * 100 are [%]

Questions marks

• Are the last generation CGCMs representing the SAM-related Are the last generation CGCMs representing the SAM-related variability appropriately?variability appropriately?

• Are those models capturing the recent observed warming in Are those models capturing the recent observed warming in the Antarctic Peninsula region?the Antarctic Peninsula region?

• Is it possible to extract an average picture of the SAM-related Is it possible to extract an average picture of the SAM-related variability in a warmer climate?variability in a warmer climate?

• Is the cryosphere sending signals about climate change?Is the cryosphere sending signals about climate change?



Based on two IPCC experimentsBased on two IPCC experiments

• 20C3M climate of the 20th century: Historical run

• SRES A2 climate change experiment: initial conditions from end of 20C3M, to 2100

Time slidesTime slides

• 1970-1999: actual climate

• 2070-2099: future climate

Selected variablesSelected variables

• ST, SLP, near surface wind and sea-ice

• SAM index is the PC-1 geop(500 hPa)


Models Institution and Country

CNRM CM3 MètèoFrance, France

GFDL CM 2.0 Geophysical Fluid Dynamics Laboratory, USA

GISS ER Goddard Institute for Space Studies, USA

IPSL CM4 Institut Pierre Simon Laplace, France

MIROC 3. 2 MedResCenter for Climate System Research, National Institute for Environmental Studies and Frontier Research Center for Global Change, Japan

MRI CGCM 2.3.2 Meteorological Research Institute, Japan

NCAR PCM National Center for Atmospheric Research, USA

Models documentation is available at www-pcmdi.llnl.gov



Multi-model ensemble mean, SLP filed

20C3M SRES A2

SRES A2 minus 20C3M

- ++

SAM Positive Phase


Multi-model Control Run

Contours are the multi-model mean

Shadows are the spread

SLP ST SIC


Control run minus reference climatologies

NCEP (SLP, ST, 1970-1999) and Hadley (SIC, 1982-1999)

SLP ST SIC

Multi-model Control Run


Multi-model Annual Mean Climate Change Projections

Control run minus SRES A2 experiment

Present climate is 1979-1999 while future climate is 2070-2099

SLP ST SIC

Ice Draft dataU.S. Navy

submarines

Ice Thickness SINTEXG spring - years 81-130

Ice Thickness SINTEXG spring - years 81-130 150 W

Sea ice thicknessComparison with observations

Image courtesy of Enrico Scoccimarro, INGV

Multi-model SAM-Positive Phase-related variability

• Climate change projects into the positive phase of the SAM in annual mean conditions

• In present climate SAM is particularly strong during the austral spring

• In future climate SAM is also strong during the austral spring (and summer)

We are going to explore into the SAM-PP-related variability and its change in a warmer climate



Present climate SAM-PP-related variability SLP SW

ST SIV

Future climate SAM-PP-related variability

ST (present conditions) SIV

ST (future conditions) SIV


Future climate SAM-PP-related variability SLP (future conditions) SW

SLP (present conditions) SW


Conclusions

We extracted a picture of the response of the SAM to increasing GHG in a multi-model ensemble produced in the framework of the 4th IPCC project.

In mean average, SLP climate change projects into the positive phase (PP) of the SAM.

We centered the attention in the surface climate variability associated with the SAM PP and its change in a warmer climate.

Particular attention is on the surroundings of the Antarctic Peninsula


Conclusions (cont.)

Over the present climate slice, the multi-model ensemble mean reproduce the regional warming around the AP associated with the SAM.

When increasing GHG, warming in the neighborhoods of the AP (and decreasing of sea-ice volume in the sea-ice edge region) intensifies.

This result suggests that recent observed sea-ice trend around the AP could be associated to anthropogenic forcings.

Surface changes in T and SI are consistent with anomalous atmospheric heat transport associated with circulation anomalies.


Word of warning …

• The confidence in sea-ice anomalies response is The confidence in sea-ice anomalies response is limited by the reduced number of models that limited by the reduced number of models that provides the information and the large inter-model provides the information and the large inter-model spread.spread.

• Even if the large scale response to the SAM variability Even if the large scale response to the SAM variability is an important driver of the AP climate change, in is an important driver of the AP climate change, in CGCMs the local interactions between the atmosphere, CGCMs the local interactions between the atmosphere, sea and sea-ice are misrepresented.sea and sea-ice are misrepresented.

! If the stratospheric ozone recovers the SAM variability If the stratospheric ozone recovers the SAM variability could also be affected (Shindell and Schmidt 2004).could also be affected (Shindell and Schmidt 2004).


We emphasize that the results need to be view with caution, given the weaknesses in the models and the uncertainties related to the future

evolution of the O3.


March 2005March 2005, preliminary results were presented at , preliminary results were presented at IPCC meeting, HawaiiIPCC meeting, Hawaii

May 2005May 2005, a manuscript was submitted to GRL (in , a manuscript was submitted to GRL (in revision)revision)

Following the IPCC schedule…


December 2005December 2005, dead-line to , dead-line to be in press, then to be included in be in press, then to be included in

the IPCC AR4the IPCC AR4

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SAM vs ENSO related variability


•Left: SAM signal

• Right: ENSO signal

Regression coefficients indicate changes in SIC [%] and T [°C] corresponding to 1standard deviation change

in the indices

Regression maps of SIC (shaded) and T at 2m (contour) anomalies, 1979-2002 (Lui et al. 2004)

Documents

Climate response associated with the Southern Annular Mode in the surroundings of Antarctic Peninsula Andrea F. Carril, Claudio G. Menéndez and Antonio