The Sou h A lan ic Dipole:
Mechanisms, a iabili y and impac s o e
Sou h Ame ica
Ani a D umond
Vale Ins i u e o Technology Sus ainable De elopmen (ITV-DS)
Wi h he collabo a ion o
Rena a Tedeschi
ITV-DS
Na an Noguei a
Michelle S. Reboi a
Fede al Uni e si y o I ajubá
25/11/2025 1
Ou line o he P esen a ion
Sou h A lan ic Clima e Backg ound
In oducing he Sou h A lan ic Dipole (SAD)
E olu ion o Scien i ic Unde s anding
Physical Mechanisms
Seasonal Va ia ions and Indices
Impac s on Sou h Ame ican Clima e
In e ac ions Wi h O he Clima e Modes
Clima e Change E ec s
Model Rep esen a ion and Fu u e P ojec ions
Final Rema ks
25/11/2025 2Ani a D umond - Sou h A lan ic Dipole (SAD)
F om p e ious lec u es:
•Teleconnec ions link dis an egions.
•Role o he oceans in clima e a iabili y
•ENSO, PDO, SAM, IOD, AMO, TAD and a ec Sou h Ame ica
•Wha abou he Sou h A lan ic Ocean? Is he e a a iabili y mode
ha can in luence he clima e in he su ounding egions?
25/11/2025 3Ani a D umond - Sou h A lan ic Dipole (SAD)
Why s udying eleconnec ions ma e s
Reboi a e al. (2021)
25/11/2025 4Ani a D umond - Sou h A lan ic Dipole (SAD)
Le ’s e iew he
main Sou h A lan ic clima ological ea u es
SASH
SASH
SPSH
SPSH
T ade
winds
SACZ
25/11/2025 5Ani a D umond - Sou h A lan ic Dipole (SAD)
And he main Sou h A lan ic oceanic ea u es
•Benguela Cu en (BeC) – cold, lowing no hwa d along he A ican coas
•Sou h Equa o ial Cu en (SEC): wes wa d low
• B azil Cu en (BC) – wa m, lowing sou hwa d along he B azilian coas
•Mal inas (Falklands) Cu en (MC): cold subpola cu en lowing no hwa d,
mee ing he wa m B azil Cu en nea 35°S
•B azil–Mal inas Con luence Zone: egion o s ong empe a u e g adien s
•Sub opical Gy e ans e s hea and momen um
•Sou h A lan ic Cu en (SAC): owa d A ica.
Ksepka and Thomas (2021)
(Reboi a e al., 2021, and e e ences he ein)
•The Sou h A lan ic Dipole (SAD) is he dominan mode o coupled
a mosphe e–ocean a iabili y o e he Sou h A lan ic
•Cha ac e ized by a no heas –sou hwes o ien ed dipole pa e n
wi h cen e s o ac ion o e he opical and ex a opical Sou h
A lan ic
•I p esen s a iabili y on in aseasonal, in e annual, and
in e decadal imescales
25/11/2025 6Ani a D umond - Sou h A lan ic Dipole (SAD)
Wha is he Sou h A lan ic Dipole (SAD)?
Co ela ion be ween SST anomalies and SVD ime coe icien s
ob ained om he SST indica ing he SAD
adap ed om Bomba di e al. (2014)
•I s in es iga ion s ill aces many challenges
•Few in-si u obse a ions o e he Sou h A lan ic and su ounding
coun ies be o e he 1980s (onse o he Sa elli e E a)
25/11/2025 7Ani a D umond - Sou h A lan ic Dipole (SAD)
Why s udying he SAD makes us eel so
sad some imes?
25/11/2025 8Ani a D umond - Sou h A lan ic Dipole (SAD)
The ERA5 global eanalysis om 1940 o 2022
Maps o da a coun s o he
con en ional pa o he obse ing
sys em, sepa a ing by icennium (20-
yea ime pe iod, om le o igh ,
excep o he las column, which shows
obse a ions un il Decembe 2022) and
by obse able ( om op o bo om).
Numbe s indica e he a e age da a
coun s assimila ed pe mon h. Whi e
a eas indica e no da a assimila ed.
Fig1 Soci e al. (2024)
•Known Impac s mainly limi ed o Sou h Ame ica and A ica
•Less a en ion compa ed o ENSO o he Indian Ocean Dipole
•Resul s a e dependen on he da a, ime pe iod, and s a is ical
me hod used
25/11/2025 9Ani a D umond - Sou h A lan ic Dipole (SAD)
Why s udying he SAD makes us eel so
sad some imes?
Ye , beyond hese challenges, he SAD o e s
many oppo uni ies o new esea ch!
Physical P ocesses
•Nnamchi e al. (2011) explain he SAD e olu ion h ough
p ocesses ha peak in win e , also showing a ocean–
a mosphe e coupling.
•New unde s anding (Man a e al., 2024)
–The SAD is shaped by bo h a mosphe ic and oceanic
a iabili y.
–Thei ela i e in luence changes wi h imescale o
oscilla ions
he SAD is complex, and he e is mo e han one way o in e p e
i s physical d i e s.
25/11/2025 16Ani a D umond - Sou h A lan ic Dipole (SAD)
Mo ioka e al. (2011) 1s SST EOF 1960-2008 (20.4%) HADISST
25/11/2025 17Ani a D umond - Sou h A lan ic Dipole (SAD)
Seasonal Va ian s: SASD and SAOD
•The SAD p esen s seasonal a ia ions (Nnamchi e al., 2017),
exp essed h ough wo main modes.
•Sou h A lan ic Sub opical Dipole (SASD)
Mo ioka e al. (2011)
• Peaks in aus al summe , when SASH
shi s sou hwa d
• Con ined o sub opical la i udes
•Sou h A lan ic Ocean Dipole (SAOD)
Nnamchi e al. (2011)
• Peaks in aus al win e , when SASH shi s
no hwa d
• Ex ends ac oss b oade la i udes Nnamchi e al. (2011) 2nd SST EOF 1950-2008
Noguei a e al. (2025) in p epa a ion
25/11/2025 18Ani a D umond - Sou h A lan ic Dipole (SAD)
How do we moni o SAD?
•Two main Indices based on SST anomaly di e ence be ween wo egions
•SAD → NE pole - SW pole
•+ SAD → wa me NE pole & coole SW pole
•Index choice may a ec esul s
Sou h A lan ic Ocean Dipole Index
SAODI –(Nnamchi e al., 2011) ed boxes
• NE pole: 10°E–20°W, 0–15°S
• SW pole: 10–40°W, 25–40°S
•I cap u es equa o ial in luences.
Sou h A lan ic Sub opical Dipole Index
SASDI –(Mo ioka e al., 2011) g een boxes
• Focuses on sub opical a iabili y
• NE pole: 0–20°W, 15–25°S
• SW pole: 10–30°W, 30–40°S
Impo an No e
• SAODI’s no he n pole o e laps he A lan ic Niño egion
• SASDI’s sou he n pole is ully inside SAODI’s sou he n domain
25/11/2025 19Ani a D umond - Sou h A lan ic Dipole (SAD)
S eng hs and Limi a ions o SAD Indices
S eng hs
• Simple and widely used o moni o ing SAD a iabili y
• Cap u e he SST dipole pa e n
Limi a ions
• Sensi i e o box de ini ions (small shi s can change index alues)
• SAODI pa ly o e laps wi h he A lan ic Niño egion → may mix signals
• Indices do no sepa a e a mosphe e–ocean coupling mechanisms
• Canno ep esen spa ial shi s (e.g., la i udinal mig a ion o SAD)
25/11/2025 20Ani a D umond - Sou h A lan ic Dipole (SAD)
Moni o ing: how do we de ine ex eme SAD e en s?
• Ex eme SAD e en s
Commonly de ined when SAODI o
SASDI exceed ±1 s anda d
de ia ion om hei clima ological
mean.
• Public ime se ies a ailable
Bo h indices (SAODI, SASDI) a e
openly p o ided by he
Teleconnec ion Index Online Tool –
Fede al Uni e si y o I ajubá
h ps://app-indice.s eamli .app/
(D umond e al., 2025; in e iew).
25/11/2025 21Ani a D umond - Sou h A lan ic Dipole (SAD)
How Does he SAD ela e wi h Sou h Ame ican Clima e?
Rela ionship be ween SAD and he SAMS
(Bomba di & Ca alho, 2011)
•SAD associa ed wi h dipole in ain all be ween
SE and NE B azil
•Nega i e SAD (cool NE pole x wa m SW pole) –
s onge SASH
SAMS (Boli ia-SE B azil) we season: ea lie onse ,
longe & we e
NE B azil we season: La e onse , sho e & d ie
•Posi i e SAD (wa m NE pole x cool SW pole) –
weake SASH
SAMS: la e onse , sho e & d ie
NE B azil: ea lie onse , longe & we e
Bomba di & Ca alho (2011)
25/11/2025 22Ani a D umond - Sou h A lan ic Dipole (SAD)
•Key p ocess (Bomba di e al., 2014): A Rossby wa e ain om he ex a opical Paci ic.
Nega i e SAD
•Cyclonic anomalies o e SE B azil
•Enhanced mois u e anspo om Amazon
•In ensi ica ion SACZ ac i i y
Posi i e SAD
•An icyclonic anomalies o e SE B azil
•Reduced mois u e in low om Amazon
owa ds SE B azil and weake SACZ ac i i y
Bomba di e al. (2014)
25/11/2025 23Ani a D umond - Sou h A lan ic Dipole (SAD)
Me hodological Sensi i i y in Assessing SAD Impac s
Me hodological choices may shape he SAD–p ecipi a ion ela ionships.
Example: SAODI - low skill in summe (weak N pole SST signal).
Analysis based on SAODI may p esen low impac du ing Summe .
Reboi a e al. (2021): SAODI composi es
— Nega i e SAODI → we e no he n SA du ing win e and sp ing
Ca penedo & da Sil a (2022): linea co ela ions using SAODI
— Excep Summe :
sou he n Ce ado: Nega i e SAODI → we e ; posi i e SAODI → d ie .
No he n B azil: Nega i e SAODI → d ie ; posi i e SAODI → we e .
25/11/2025 24Ani a D umond - Sou h A lan ic Dipole (SAD)
How Does he SAD In e ac Wi h
O he Clima e Modes?
SAD and O he Sou he n Hemisphe e Dipoles
25/11/2025 25Ani a D umond - Sou h A lan ic Dipole (SAD)
•SAD o en occu s wi h o he dipole pa e ns in SH: SIOD (Sou h
Indian Ocean Dipole) and Sou h Paci ic dipole, mainly in summe
(e.g. Venegas e al., 1997; He mes & Reason, 2005; Yu e al., 2023).
•These dipoles a e in luenced by la ge-scale a mosphe ic wa e
pa e n in SH ci cula ion known as he zonal wa enumbe -3/4
•These wa e pa e ns modi y sub opical an icyclones, igge ing
he dipoles
Reg ession maps o he SST anomalies (C) on he summe ime indice o SAOD o e 1979–1999.
Yu e al. (2023)
Final Rema ks
•Clima e change: changes in ENSO egime and eleconec ions;
expansion o SASH ha shi s SACZ and SAD sou hwa d
•CMIP6 models ep oduce he SAD basic pa e ns bu ail o cap u e
some ocean–a mosphe e coupling and show la ge unce ain y in
u u e SAD– ain all p ojec ions.
•Key open ques ions:
•Long- e m ends and mechanisms behind SAD seasonali y
•Changing ENSO–SAD link
•P edic abili y and ole o ocean–a mosphe e coupling
•Regional impac s in Sou h Ame ica and A ica
25/11/2025 32Ani a D umond - Sou h A lan ic Dipole (SAD)
25/11/2025 33Ani a D umond - Sou h A lan ic Dipole (SAD)
Acknowledgemen s
Pos doc suppo ed by p ojec R100603.PMP
Thank you!
ani [email p o ec ed]
Bie , A. A. (2023). Changes in he Sou h A lan ic Dipole and impac s on he clima e o Sou h Ame ica unde he aspec o clima e
change. Doc o al Thesis, Ins i u o de As onomia, Geo ísica e Ciências A mos é icas, Uni e si y o São Paulo, São Paulo.
doi:10.11606/T.14.2023. de-04032024-194824. Re ie ed 2025-11-17, om www. eses.usp.b
Bomba di, R. J., & Ca alho, L. M. (2011). The Sou h A lan ic dipole and a ia ions in he cha ac e is ics o he Sou h Ame ican
Monsoon in he WCRP-CMIP3 mul i-model simula ions. Clima e Dynamics, 36, 2091-2102.
Bomba di, R.J., L.M.V. Ca alho & C. Jones. 2014. P ecipi a ion o e eas e n Sou h Ame ica and he Sou h A lan ic Sea su ace
empe a u e du ing neu al ENSO pe iods. Clim. Dyn. 42: 1553–1568.
Boscha , G., Te ay, P., & Masson, S. (2013). Ex a opical o cing o ENSO. Geophysical Resea ch Le e s,40(8), 1605-1611.
Ca penedo, C. B., & Da Sil a, C. B. (2022). In luência de eleconexões na p ecipi ação plu ial do ce ado b asilei o. Re is a
B asilei a de Clima ologia,30, 26-46.
D umond, A. R. D. M., & Amb izzi, T. (2005). The ole o SST on he Sou h Ame ican a mosphe ic ci cula ion du ing Janua y,
Feb ua y and Ma ch 2001. Clima e Dynamics, 24(7), 781-791.
D umond, A.; Noguei a, N. C. O; Reboi a, M. S.; Miguel, G. C. (2025). Teleconnec ion Indices: an upda ed e sion o he cu en
clima e. In e iew in CLIVAR Exchange.
Ham, Y. e al. In e ‐Basin In e ac ion Be ween Va iabili y in he Sou h A lan ic Ocean and he El Niño/Sou he n Oscilla ion.
Geophysical Resea ch Le e s, . 48, n. 15, 5 ago. 2021.
He mes, J. C., & Reason, C. J. C. (2005). Ocean model diagnosis o in e annual coe ol ing SST a iabili y in he Sou h Indian and
Sou h A lan ic Oceans. Jou nal o Clima e,18(15), 2864-2882.
Kayano, M.T., R.V. And eoli & R.A.F. Souza. 2012. Rela ions be ween ENSO and he Sou h A lan ic SST modes and hei e ec s on
he Sou h Ame ican ain all. In . J. Clima ol. 33: 2008–2023.
Re e ences
Ksepka, D. T., & Thomas, D. B. (2012). Mul iple cenozoic in asions o A ica by penguins (A es, Sphenisci o mes). P oceedings o
he Royal Socie y B: Biological Sciences, 279(1730), 1027-1032.
Man a, G., Bach, E., Talen o, S., Ba ei o, M., Speich, S., & Ghil, M. (2024). The Sou h A lan ic Dipole ia mul ichannel singula
spec um analysis. Scien i ic Repo s, 14(1), 15534.
Ma ín-Gómez, V., Ba ei o, M., & Mohino, E. (2020). Sou he n Hemisphe e sensi i i y o ENSO pa e ns and in ensi ies: Impac s
o e sub opical Sou h Ame ica. A mosphe e,11(1), 77.
Mo ioka, Y., T. Tozuka & T. Yamaga a. 2011. On he g ow h and decay o he Sub opical Dipole Mode in he Sou h A lan ic. J. Clim.
24: 5538–5554.
Mo ioka, Y. e al. Role o opical SST a iabili y on he o ma ion o sub opical dipoles. J. Clim. 27, 4486–4507. h ps:// doi.
o g/10. 1175/ JCLI-D- 13- 00506.1 (2014).
Nnamchi, H.C., J. Li & R.N.C. Anyadike. 2011. Does a dipole mode eally exis in he Sou h A lan ic Ocean? J. Geophys. Res. A mos.
116: D15104.
Nnamchi, H.C., F. Kucha ski, N.S. Keenlyside, e al. 2017. Analogous seasonal e olu ion o he Sou h A lan ic SST dipole indices.
A mos. Sci. Le . 18: 396–402.
Nwo gu, U. C., Nnamchi, H. C., & Rosá io, N. E. (2024). Di e gen u u e change in Sou h A lan ic Ocean Dipole impac s on egional
ain all in CMIP6 models. En i onmen al Resea ch: Clima e,3(3), 035002.
Palas anga, V., Ve a, C. S., & Piola, A. R. (2002). On he leading modes o sea su ace empe a u e a iabili y in he Sou h A lan ic
Ocean. Cli a Exchanges, 7(3-4), 12-15.
Reboi a, M. S., Amb izzi, T., C espo, N. M., Du a, L. M. M., Fe ei a, G. W. D. S., Rehbein, A., ... & Souza, C. A. D. (2021). Impac s o
eleconnec ion pa e ns on Sou h Ame ica clima e. Annals o he New Yo k Academy o Sciences, 1504(1), 116-153.
Re e ences
Rod igues, R. R., Campos, E. J. D. & Haa sma, R. The Impac o ENSO on he Sou h A lan ic Sub opical Dipole Mode. J. Clim. 28,
2691–2705. h ps:// doi. o g/ 10. 1175/ JCLI-D- 14- 00483.1 (2015).
Soci, C., He sbach, H., Simmons, A., Poli, P., Bell, B., Be is o d, P., e al. (2024) The ERA5 global eanalysis om 1940 o
2022. Qua e ly Jou nal o he Royal Me eo ological Socie y, 150(764), 4014–4048. A ailable
om: h ps://doi.o g/10.1002/qj.4803
Venegas, S. A., Mysak, L. A., & S aub, D. N. (1997). A mosphe e–ocean coupled a iabili y in he Sou h A lan ic. Jou nal o
Clima e, 10(11), 2904-2920.
Wang, L., Yu, J. Y., & Paek, H. (2017). Enhanced biennial a iabili y in he Paci ic due o A lan ic capaci o e ec . Na u e
communica ions,8(1), 14887.
Yu, L., Zhong, S., Winkle , J. A., Zhou, M., Lenschow, D. H., Li, B., ... & Yang, Q. (2017). Possible connec ions o he opposi e ends
in A c ic and An a c ic sea-ice co e . Scien i ic epo s,7(1), 45804.
Yu, L., Zhong, S., Vihma, T., Sui, C., & Sun, B. (2022). A change in he ela ion be ween he Sub opical Indian Ocean Dipole and he
Sou h A lan ic Ocean Dipole indices in he pas ou decades. A mosphe ic Chemis y and Physics Discussions,2022, 1-22.
Yu, L., Zhong, S., Vihma, T., Sui, C., & Sun, B. (2023). A change in he ela ionship be ween ENSO and he Sou h A lan ic Sub opical
Dipole in he pas ou decades. EGUsphe e,2023, 1-30.
Yu, L., Zhong, S., Vihma, T., Sui, C., & Sun, B. (2024). Mul idecadal a ia ions in No h A lan ic SSTs modula e he ela ionship
be ween ENSO and he Sou h A lan ic Sub opical Dipole since 1900. En i onmen al Resea ch Le e s,19(9), 094001.
ZILLI, M. T.; CARVALHO, L. M. V.; LINTNER, B. R. The polewa d shi o Sou h A lan ic Con e gence Zone in ecen decades. Clima e
Dynamics, . 52, n. 5–6, p. 2545–2563, 30 ma . 2019.
Re e ences
