La salinité de surface, thème fédérateur d’OLVAC
description
Transcript of La salinité de surface, thème fédérateur d’OLVAC
La salinité de surface, thème fédérateur d’OLVAC
Thématique présente sur tous les chantiers géographiques OLVAC, à différentes échelles spatio-temporelles, centrale dans plusieurs thèses
Etudes s’appuyant sur le SO SSS, les satellites SMOS/Aquarius, la modélisation
impact des fleuves
dynamique IOD
circulation australe
dynamique ENSO
dynamique saisonnière
climat régional
tendances climatiques long terme
ENSO-related SSS changes
Eastern Pacific El Niño Central Pacific El Niño
SST
Different SSS anomalies near the eastern edge of WP fresh pool and under SPCZ
(Singh, Delcroix & Cravatte, 2011)
SSS
Associated equatorial mechanisms
(Hasson, Delcroix & Dussin, 2013)pss/yr
1996
-199
8 E
aste
rn P
acifi
c E
l Niñ
o
2001
-200
4 C
entr
al P
acifi
c E
l Niñ
o
Mixed layer salt budget in forced model:
- advection term not extending eastward of dateline in CP Niño
- no eastern precipitation forcing in CP Niño
- strong subsurface forcing in EP Niño
Summer rain => SSS minimum, fresh pool buildingWestward advection of fresh pool by SECEkman pumping => upwelling in Panama Bight, fresh pool destruction
Wind/Rain JAS
Surface Currents JFM
Panama gap wind
Upwelling
East Pacific Fresh Pool seasonal cycle
(Alory, Maes, Delcroix, Reul & Illig, 2012)
SMOS
SMOS can monitor the fresh pool
Impact of river discharges in Bay of Bengal
(Durand, Papa, Rahman & Bala, 2011)
Ganges + Brahmaputra
SSS with seasonal runoff
+ interannual runoff anomaly
resulting SST anomaly
Model simulations with or without interannual runoff anomaly
1998: strong discharge
Indian Ocean Dipole SSS signature
(Durand, Alory, Reul & Dussin, en cours)
Validation
SMOS SSS 12/2011 – 12/2010
SMOS SSSin situ SSSWOA SSS Both data and model agree on dominant role of advection
IOD+
IOD-
2010 2012
Largest year-to-year signal in SMOS data, related to IOD-/IOD+ succession
Tropical Atlantic SSS budget from mixed layer model
(Da-Allada, Alory, Dupenhoat, Kestenare, Durand & Hounkonnou, 2013)
m
m
hm
emmm
mm SKh
SSwHSu
h
SRPE
t
S m 2)(.
Climatological model validation
Dominant processes for mean state
Seasonal balance in selected regions
(Morrow & Kestenare, en cours)
SAZ
AZ
201220001993
SAZ : SSS – Seasonal mean (DJFM)
CorrelationMaria Is TSG
Southward penetration of Tasman Sea inflow
Interannual variations in SURVOSTRAL SubAntarctic Zone
Global SSS trends (1970-2002)Obs Mean SSS
Obs SSS trend
CMIP3 models SSS trend
(Terray, Corre, Cravatte, Delcroix, Reverdin & Ribes, 2012)
- Observed trends reflect the « wet gets wetter, dry gets drier » Clausius-Clapeyron effect
- Local effect + mean currents
- Models capture the increasing Pacific-Atlantic contrast despite biases (double ITCZ)
Conclusion
• Poursuivre les observations sur le long-terme (in situ + satellite)
• Bonne synergie entre SO et recherche associée (CNAP)
• Transversalité: cycle de l’eau, couplage
océan-atmosphère...
Bon week-end!