CLIVAR TROPICAL ATLANTIC MEETING

1
CLIVAR TROPICAL ATLANTIC MEETING Paris, 18-20
October 2006

• Session topics
• - Tropical basin circulation
• - Equatorial waves and currents
• - Equatorial SST and currents
• - Upper ocean processes
• - Air-sea coupling

2
Questions/Issues on mean circulation

• 1. Pathways of the MOC through the tropics
• - What is the partitioning between western
  boundary (including rings) and interior pathways?
• - Interaction with STCs?
• - Interior pathways in the subtropics?
• 2. Role of zonal equatorial currents (and other
  circulation features)
• in supplying waters to the eastern upwelling
  zones.
• - What are the climatological transports and
  seasonal cycles of the EUC, SEUC, NEUC, and
  where/how do they terminate?
• - Ventilation (and export) from the oxygen
  minimum zone? Oxygen as a sensitive indicator of
  change, trend decreasing physical (T-S,
  solubility) biological (effect of
  stratification on nutrient supply and
  utilization efficiency)

3
Questions/Issues on Variability

• 1. Intraseasonal
• - What is the cause/dynamics of the 14-17
  day variability in the equatorial waveguide?
• - What is the cause of the strong interannual
  variability in the intraseasonal band (i.e.,
  TIWs)?
• - What are the rectified impacts of these
  fluctuations? Implications for heat budget? Role
  in driving mean currents?
• 2. Seasonal
• - What is the EUC seasonal cycle across the
  basin and extent of its eastward penetration?
• - How do barrier layers (and associated
  temperature inversions) in the WHWP region
  influence the seasonal SST cycle there?

4
Questions/Issues on Variability

• 3. Interannual
• - MOC Interaction with the STCs How does
  STC variability influence the MOC pathways (and
  vice-versa)?
• - Is there a positive feedback between the
  ocean circulation in the tropics (e.g. STC
  convergence) and the meridional mode?
• - Where does the memory of a boreal spring
  meridional mode event into the following spring
  reside (Chiang et al. 2002)?
• - How do the zonal equatorial currents vary
  interannually in relation to TAV (e.g., does the
  EUCs transport and eastward penetration vary
  systematically during Atlantic Nino events?)

5
FLAME Interannually-Forced Simulation
EUC eastward penetration Climatological
seasonal cycle
6
Funded U.S. Moorings for extended EUC/cold tongue
Experiment
Intensive cold tongue experiment for 2009
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TACE Proposed Observing System Enhancements
Intensive float, drifter array, observational
network of oxygen sensors, focused modeling
component
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(No Transcript)
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Issue 1 Pathways of the MOC through the tropics
Fratantoni et al. (2000)
Hazeleger and Drijfhout (2006)
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Issue 1 Pathways of the MOC through the tropics

• Questions
• 1. What is the partitioning between western
  boundary (including rings) and interior pathways?
• 2. MOC Interaction with the STCs
• - How does STC variability influence the MOC
  pathways (and vice-versa)?

11
Issue 2 Influence of STC variability on TAV
SST and Wind Stress onto Total Convergence
(10?S-10?N)
R. Rodrigues
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Issue 2 Influence of STC variability on TAV

• Questions
• 1. Where does the memory of a boreal spring
  meridional mode event into the following spring
  reside (Chiang et al. 2002)?
• 2. Is there a positive feedback between the ocean
  circulation in the tropics (e.g. STC convergence)
  and the meridional mode?

13
Issue 3 Role of zonal equatorial currents (and
other circulation features) in supplying waters
to the eastern upwelling zones
14
Issue 3 Role of zonal equatorial currents (and
other circulation features) in supplying waters
to the eastern upwelling zones

• Questions
• 1. What are the climatological transports and
  seasonal cycles of the EUC, SEUC, NEUC, and
  where/how do they terminate?
• 2. How do they vary interannually in relation to
  TAV (e.g., does the EUCs transport and eastward
  penetration vary systematically during Altlantic
  Nino events?)
• 3. Ventilation (and export) from the oxygen
  minimum zone?