vertical thermohaline structure of mesoscale eddies in the ... · vertical thermohaline structure...

Vertical thermohaline structure of mesoscale eddies in the four major Eastern Boundary Upwelling Systems

Cori Pegliasco1*, Alexis Chaigneau1, Rosemary Morrow1, Yves Morel 1

* Presenting author

1) Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS), France

cori.pegliasco@legos.obs-mip.fr

Introduction

Eastern Boundary Upwelling Systems (EBUS) are caracterized by:

→ Cold and productive water upwelled near the coast

CALUS

CANUS

BENUSPCUS

Introduction

Eastern Boundary Upwelling Systems (EBUS) are caracterized by:

[Colas, 2008]

x

PCUS

→ Cold and productive water upwelled near the coast→ Equatoward surface currents→ Poleward subsurface currents

CALUS

CANUS

BENUS

Introduction

Eastern Boundary Upwelling Systems (EBUS) are caracterized by:

[Colas, 2008]

x

x

[Barton, 2004]

x

x

[Veitch, 2010]

→ Cold and productive water upwelled near the coast→ Equatoward surface currents→ Poleward subsurface currents→ Strong vertical shear

CALUS

[Marchesiello, 2002]

CANUS

BENUSPCUS

Introduction

Eddy genesis

[Chaigneau et al., 2009]

Introduction

Eddy genesis

[Chaigneau et al., 2009]

Eddy propagation velocity

Introduction

Eddy genesis

[Chaigneau et al., 2009]

Eddy propagation velocity

Do eddies also share similar vertical structure ?

Objective

Depict the eddy vertical structure in the 4 EBUS,combining altimetry and ARGO floats profiles

Objective

Depict the eddy vertical structure in the 4 EBUS,combining altimetry and ARGO floats profiles

[Yu et al., 2012]

CEs AEs

[Chaigneau et al., 2011] θ' (°C)

[Yang et al., 2013]

North-West Pacific North-West Pacific South-East Pacific

Data & Method

Weekly altimetry maps

2001 - 2012

Automated eddy detection skills (amplitude > 2 cm)[Chaigneau et al., 2008]

PCUS

Data & Method

PCUSARGO profiles

+altimetry

Classification of the ARGO profiles within CE, AE or outside eddies

4 CEs4 AEs14 Out

Profiles :

Data & Method

Outside Eddies (OEs) ~60 %

4450

8000

9800

8700

2100

3000

26001300

2900

2300

13002300

Cyclonic Eddies (CEs) ~20 %

Anticyclonic Eddies (AEs) ~20 %

Data & Method

Outside Eddies (OEs) ~60 %

4450

8000

9800

8700

2100

3000

26001300

2900

2300

13002300

Cyclonic Eddies (CEs) ~20 %

Anticyclonic Eddies (AEs) ~20 %

→ Temperature and salinity anomalies

Data & Method

< 200 km+/- 1 month

→ local mean

PCUS

Data & Method

Done for all the availables profiles→ within AEs→ within CEs

→ outside eddies

PCUS

Results : Mean temperature anomaly

AEs

CEs

OEs

Results : Mean temperature anomaly

AEs

CEs

OEs

Results : Mean temperature anomaly

T' : -150m-0,45 °C T' : -330m

0,3°C

Results : Mean temperature anomaly

T' : -120m-0,6 °C

T' : -170m 0,5°C

Results : Mean temperature anomaly

T1' : -80m

-0,5 °C

T1' : -70m

0,5°C

Results : Mean temperature anomaly

T1' : -80m

-0,5 °C

T1' : -70m

0,5°C

T2' : -1360m

0,1°C T

2' : -1460m

0,1°C

Results : Mean temperature anomaly

T1' : -160m

-0,4 °CT

1' : -230m

0,5°C

Results : Mean temperature anomaly

T1' : -160m

-0,4 °CT

1' : -230m

0,5°C

T2' : -470m

-0,4 °CT

2' : -500m

0,5°C

Results : Mean temperature anomaly

Enough Argo profiles to look more in details

Results : Mean temperature anomaly in subregions (CANUS)

CANUS

Mean anomaly

Results : Mean temperature anomaly in subregions (CANUS)

CANUS

Mean anomaly

[Barton, 2004]

Cape Verde Frontal Zone

Results : Mean temperature anomaly in subregions (CANUS)

CANUS

Mean anomaly

Cape Verde Frontal Zone

Meddies influence

[Richardson, 1998]

Temperature within a Meddy[Richardson, 2000]

« Meddy » profile

Results : Mean temperature anomaly in subregions (BENUS)

BENUS

Mean anomaly

Results : Mean temperature anomaly in subregions (BENUS)

BENUS

Mean anomaly

Few eddies + few profiles

Profiles withinCEs

Profiles withinAEs

Results : Mean temperature anomaly in subregions (BENUS)

BENUS

Mean anomaly

[Veitch, 2010]

[Matano, 2003]

Conclusions

● Altimetry + Argo floats profiles → efficient tool to reconstruct the eddy vertical structure

+ =

CALUS

Conclusions

● Altimetry + Argo floats profiles→ efficient tool to reconstruct the eddy vertical structure

● Strong differences between each EBUS

PCUS CALUS BENUS CANUS

+ =

CALUS

Conclusions

● Altimetry + Argo floats profiles→ efficient tool to reconstruct the eddy vertical structure

● Strong differences between each EBUS

● Strong heterogeneity within each EBUS

PCUS CALUS BENUS CANUS

North

South

+ =

CALUS

Perspectives

● Work on salinity anomalies

T' S' T' S'

PCUS CANUS

Perspectives

● Work on salinity anomalies

● Track eddies in time and space to depict the evolution of their vertical structure

T' S' T' S'

PCUS CANUS

[Sangra, 2009]

Perspectives

● Work on salinity anomalies

● Track eddies in time and space to depict the evolution of their vertical structure

● Separate the different kinds of eddies

T' S'

→ « Meddy » profile

→ « North » profile

→ « South » profile

T' S'

PCUS CANUS

[Sangra, 2009]

AEs

Perspectives

● Work on salinity anomalies

● Track eddies in time and space to depict the evolution of their vertical structure

● Separate the different kinds of eddies

● Find the dynamicals mecanisms leading to such different structures

T' S'

→ « Meddy » profile

→ « North » profile

→ « South » profile

T' S'

PCUS CANUS

[Sangra, 2009]

AEs

Mean Temperature anomaly

Mean Salinity anomaly

PCUS Subregions : Salinity anomaly

CALUS Subregions : Salinity anomaly

CANUS Subregions : Salinity anomaly

BENUS Subregions : Salinity anomaly

PCUS Subregions : Temperature anomaly

PCUS

Mean anomaly

Mean anomaly

[Parada et al., 2012]

PCUS Subregions : Temperature anomaly

CALUS

Mean anomaly

CALUS Subregions : Temperature anomaly

CALUS

Mean anomaly

[Strub and James, 2002]

CALUS Subregions : Temperature anomaly

Clustering : « water classes »

● Cluster analysis (comparing similarities)

→ Consistent with the local circulation

→ Between T and S profiles :

Clustering : AEs of CANUS

● Cluster analysis (comparing similarities)

→ Between T and S anomalies profiles within AEs→ Between T and S profiles

→ « Meddy » profile

→ « North » profile

→ « South » profile

● Cluster analysis (comparing similarities)

→ Between T and S anomalies profiles within AEs→ Between T and S anomalies profiles within CEs

→ Between T and S profiles

→ « Meddy ? » profile

→ « North » profile

→ « South » profile

Clustering : CEs of CANUS