Large scale SSS inter-annual variability in tropical Indian and Pacific Oceans
17
QWG10, Boutin & Hernandez Large scale SSS inter-annual variability in tropical Indian and Pacific Oceans J. Boutin 1 , O. Hernandez 1 , N. Martin 1 , G. Reverdin 1 , F. Gaillard 2 , S. Morrisset 1 1 CNRS/LOCEAN (CNRS-UPMC-IRD) Paris, France 2 IFREMER/LPO (CNRS-Ifremer-IRD-UBO), Plouzané, France + collaborations with French GLOSCAL SMOS Cal/Val project
description
Large scale SSS inter-annual variability in tropical Indian and Pacific Oceans. J. Boutin 1 , O. Hernandez 1 , N. Martin 1 , G. Reverdin 1 , F. Gaillard 2 , S. Morrisset 1 1 CNRS/LOCEAN (CNRS-UPMC-IRD) Paris, France 2 IFREMER/LPO (CNRS-Ifremer-IRD-UBO), Plouzané, France - PowerPoint PPT Presentation
Transcript of Large scale SSS inter-annual variability in tropical Indian and Pacific Oceans
QWG10, Boutin & Hernandez
Large scale SSS inter-annual variability in tropical Indian and
Pacific Oceans
J. Boutin1, O. Hernandez1, N. Martin1, G. Reverdin1, F. Gaillard2, S. Morrisset1
1 CNRS/LOCEAN (CNRS-UPMC-IRD) Paris, France2 IFREMER/LPO (CNRS-Ifremer-IRD-UBO), Plouzané, France
+ collaborations withFrench GLOSCAL SMOS Cal/Val project
2010 : Strong la Niña and negative phase of the Indian Ocean Dipole (IOD)
Strong la Niña
These events are known to generate large scale SSS anomalies in the tropics (e.g. Gouriou et Delcroix, 2002, Singh et al. 2011, Grunseich et al. 2011)
Introduction
- IOD
QWG10, Boutin & Hernandez
DATA:
SMOS SSS
ESA v5 reprocessing; monthly maps averaged as in (Boutin et al., TGRS, 2012)
ARGO + TSG OPTIMAL INTERPOLATED SSS MAPS (ISAS)
Monthly maps from In-Situ Analysis System v6 (F. Gaillard, LPO/IFREMER, pers.
Comm.)http://wwz.ifremer.fr/lpo/SO-Argo/Products/Global-Ocean-T-S
SEA SURFACE AUTONOMOUS DRIFTER SSS
Upper S at 45cm depth; Pacific Gyre drifter (Reverdin and Morrisset, LOCEAN)http://www.locean-ipsl.upmc.fr/smos/drifters
METHOD:
COMPARISON OF SSS ANOMALIES BETWEEN 2010 AND 2011 AS DERIVED BY ISAS AND BY
SMOS
Data & Methods
QWG10, Boutin & Hernandez
High contrasted SSS signal between 2010 and 2011
November 2011-2010July 2011-2010
Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences
In the Pacific Ocean, 2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ
QWG10, Boutin & Hernandez
High contrasted SSS signal between 2010 and 2011
November 2011-2010July 2011-2010
Grunseich et al. 2011
SSS Anomaly (1975 – CLM ) Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences
In the Pacific Ocean 2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ
In the Indian Ocean : SSS differences consistent with SSS anomalies reported during negative IOD coupled with Strong La niña event (Grunseich et al. 2011)
+
+-
+
+-
QWG10, Boutin & Hernandez
High contrasted SSS signal between 2010 and 2011
November 2011-2010July 2011-2010
Grunseich et al. 2011
SSS Anomaly (1975 – CLM ) Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences
2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ
In the Indian Ocean : SSS differences consistent with SSS anomalies reported during negative IOD coupled with Strong La niña event (Grunseich et al. 2011)
+
+-
+
+-
+
+-
QWG10, Boutin & Hernandez
QWG10, Boutin & Hernandez
At first order good consistency in SMOS and ISAS 2011-2010 variability but...
July 2011-July2010 November 2011-November 2010
Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomaliesWhy? effect of ARGO/TSG undersampling (=> OI smoothing) and/or a systematic underestimate of SMOS SSS in low SSS/rainy/stratified regions?
ISAS
SMOS
QWG10, Boutin & Hernandez
2011-2010 SSS in N. Trop. Pac. (5°N-15°N)SSS anomaly July 2011-2010
ISAS
SMOS
Larger westward extent of the fresh SSS as seen by SMOS than by ARGO : stratification or ARGO undersampling?
SSS July 2010
QWG10, Boutin & Hernandez
2011-2010 SSS in 30°S-0°N region
July 2011-July2010
Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomalies
ISAS
SMOS
QWG10, Boutin & Hernandez
2011-2010 SSS in 30°S-0°N regionJuly 2011-July2010
Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomalies
July2010
ISAS
SMOS
Fresh region in 2010 fresher on SMOS than ISAS and very few ARGO in fresh region
QWG10, Boutin & Hernandez
June 2010 SSS in 30°S-0°N regionSurface autonomous drifter (S at 45cm depth)
June 2010
Again fresh region in 2010 fresher in SMOS than in ISAS maps
DRIFTER SMOS MONTHLY
ISAS MONTHLY
SSS ISAS
SSS SMOS
Summary
At first order, strong 2011-2010 SSS interannual variability in tropical oceans consistently seen by SMOS and ARGO
At first order, in the Pacific Ocean, strong 2011-2010 SSS differences associated with displacement of the ITCZ and SPCZ during La Niña event ; in the Indian Ocean : SSS differences consistent with SSS anomalies already reported during negative IOD coupled with Strong La Niña event
1°x1° 10 days & monthly SMOS SSS (1cm depth) fresher than ARGO & ISAS SSS (~5m depth) in rainy regions : 2 hypothesis:
surface stratification and rain effect
In situ undersampling and OI smoothing
To go further:
-apply a similar smoothing to SMOS and ARGO measurements
-look at 2012...
QWG10, Boutin & Hernandez
QWG10, Boutin & Hernandez
EXTRA SLIDES
QWG10, Boutin & Hernandez
SSS SMOS
2011 - 2010 SSS differences associated with displacement of the ITCZ and rainy regions
In the Indian Ocean : Saltier SSS in 2010 associated with smaller rain rate during preceding month
High anomaly around Madagascar not consistent with rainy events.
November 2011-2010
October 2011-2010
November 2011-2010
RAIN RATE
?
?
Precipitation impact on large scale SSS variability
Lower SSS on SMOS than on ISAS when Rain Rate increased
