Role of the Southern Ocean in controlling the Atlantic meridional overturning circulation Igor Kamenkovich RSMAS, University of Miami, Miami RSMAS, University.

Slides:



Advertisements
Similar presentations
Global climate responses to perturbations in Antarctic Intermediate Water Jennifer Graham Prof K. Heywood, Prof. D. Stevens, Dr Z. Wang (BAS)
Advertisements

Introduction to the Lagrangian Isopycnal Dispersion Experiment in the North Atlantic Long Zhou.
NOClim Module A Theory and modelling of the meridional oceanic heat transport Joe LaCasce (met.no) Arne Melsom (met.no) Ole Anders Nøst (NPI) Tore Furevik.
Modeling the MOC Ronald J Stouffer Geophysical Fluid Dynamics Laboratory NOAA The views described here are solely those of the presenter and not of GFDL/NOAA/DOC.
Wind-Driven Circulation in a Stratified Ocean Consider the ocean in several isopycnal layers that can be separated into two groups: Layers that outcrop.
On the Origin of Antarctic Warming Events: A Modeling Study of Causes and Effects Oliver Timm, Laurie Menviel, Axel Timmermann International Pacific Research.
The tropical Atlantic circulation: a comparision between ORCA025, ORCA05 and FLAME 1/12° Drakkar-Meeting Grenoble, Sabine Hüttl.
Dynamics V: response of the ocean to wind (Langmuir circulation, mixed layer, Ekman layer) L. Talley Fall, 2014 Surface mixed layer - Langmuir circulation.
Geophysical Fluid Dynamics Laboratory Review June 30 - July 2, 2009 Geophysical Fluid Dynamics Laboratory Review June 30 - July 2, 2009.
Diagnosing Eddy Mixing in the Southern Ocean from SOSE Ryan Abernathey With John Marshall, Matt Mazzloff and Emily Shuckburgh.
Propagation of wave signals along the western boundary and their link to ocean overturning in the North Atlantic Vassil Roussenov 1, Ric Williams 1 Chris.
El Nino Southern Oscillation (ENSO) 20 April 06 Byoung-Cheol Kim METEO 6030 Earth Climate System.
Oceanic Circulation Current = a moving mass of water.
Review High Resolution Modeling of Steric Sea-level Rise Tatsuo Suzuki (FRCGC,JAMSTEC) Understanding Sea-level Rise and Variability 6-9 June, 2006 Paris,
Potential temperature ( o C, Levitus 1994) Surface Global zonal mean.
On the Mechanisms of the Late 20 th century sea-surface temperature trends in the Southern Ocean Sergey Kravtsov University of Wisconsin-Milwaukee Department.
1 Geophysical Fluid Dynamics Laboratory Review June 30 - July 2, 2009.
Rotating Fluid -Part II A “GFD view” of the Ocean and the Atmosphere (a follow up Raymond’s Lectures) Arnaud Czaja.
The meridional coherence of the North Atlantic meridional overturning circulation Rory Bingham Proudman Oceanographic Laboratory Coauthors: Chris Hughes,
Water masses of the Southern Ocean: Their formation, circulation and global role Igor V. Kamenkovich University of Washington, Seattle.
Evaporative heat flux (Q e ) 51% of the heat input into the ocean is used for evaporation. Evaporation starts when the air over the ocean is unsaturated.
Two research cruises were successfully conducted in 2013 and Shipboard and moored observations show that: at first glance no significant decadal.
Model LSW formation rate (2 yr averages) estimated from: (red) CFC-12 inventories, (black) mixed layer depth and (green) volume transport residual. Also.
1-Slide Summary Explicit Southern Ocean eddies respond to forcing differently than parameterizations.  We need eddy resolving ocean climate models. Spurious.
Towards higher resolution, global-ocean, tracer simulations
Ventilation of the Equatorial Atlantic P. Brandt, R. J. Greatbatch, M. Claus, S.-H. Didwischus, J. Hahn GEOMAR Helmholtz Centre for Ocean Research Kiel.
Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy-premitting resolution Barnier Bernard et al.
EFFECTS OF OCEAN MIXING ON HURRICANE HEAT CONTENT ESTIMATES: A NUMERICAL STUDY S. DANIEL JACOB and LYNN K. SHAY Meteorology and Physical Oceanography Rosenstiel.
The Gent-McWilliams parameterization of ocean eddies in climate models Peter Gent National Center for Atmospheric Research.
Impact of freshwater release in the Southern Ocean on the Atlantic Didier Swingedouw.
Antarctic Climate Response to Ozone Depletion in a Fine Resolution Ocean Climate Mode by Cecilia Bitz 1 and Lorenzo Polvani 2 1 Atmospheric Sciences, University.
The Southern Ocean geography, principal fronts, and oceanographic zones (see Table 13.1). The Subtropical Front (STF) is the oceanographic northern boundary.
Ventilation of the Equatorial Atlantic P. Brandt, R. J. Greatbatch, M. Claus, S.-H. Didwischus, J. Hahn GEOMAR Helmholtz Centre for Ocean Research Kiel.
An example of vertical profiles of temperature, salinity and density.
Transport Measures Meridional overturning, MOC: MOC on density surfaces: Heat transport (rel. 0 o C): Freshwater transport (rel. 35 psu):
Law et al 2008; Matear & Lenton 2008; McNeil & Matear 2008 Impact of historical climate change on the Southern Ocean carbon cycle and implications for.
North Atlantic dynamical response to high latitude perturbations in buoyancy forcing Vassil Roussenov, Ric Williams & Chris Hughes How changes in the high.
Paris, EU-THOR, Nov25-26, 2009 Response of the North Atlantic Circulation to the realistic and anomalous wind stress Yongqi Gao, Helge Drange, Mats Bentsen.
Geopotential and isobaric surfaces
One float case study The Argo float ( ) floating in the middle region of Indian Ocean was chosen for this study. In Figure 5, the MLD (red line),
Western boundary circulation in the tropical South Atlantic and its relation to Tropical Atlantic Variability Rebecca Hummels1, Peter Brandt1, Marcus Dengler1,
Role of eddies in ocean circulation TOPEX e.g. vanishing of ‘Deacon Cell’ What can we infer from observations? Doos and Webb Danabasoglu, McWilliams Models.
Ocean Climate Simulations with Uncoupled HYCOM and Fully Coupled CCSM3/HYCOM Jianjun Yin and Eric Chassignet Center for Ocean-Atmospheric Prediction Studies.
On the effect of the Greenland Scotland Ridge on the dense water formation in the Nordic Seas Dorotea Iovino NoClim/ProClim meeting 4-6 September 2006.
Propagation of wave signals along the western boundary and their link to ocean overturning in the North Atlantic Vassil Roussenov 1, Ric Williams 1 Chris.
Interannual to decadal variability of circulation in the northern Japan/East Sea, Dmitry Stepanov 1, Victoriia Stepanova 1 and Anatoly Gusev.
Mesoscale eddies and deep upwelling in the Southern Ocean
Forces and accelerations in a fluid: (a) acceleration, (b) advection, (c) pressure gradient force, (d) gravity, and (e) acceleration associated with viscosity.
Tropical Atlantic SST in coupled models; sensitivity to vertical mixing Wilco Hazeleger Rein Haarsma KNMI Oceanographic Research The Netherlands.
Seasonal Variations of MOC in the South Atlantic from Observations and Numerical Models Shenfu Dong CIMAS, University of Miami, and NOAA/AOML Coauthors:
FIGURE S14.1 (a) Two-dimensional schematic of the interconnected NADW, IDW, PDW, and AABW cells of Figure (b). Global overturning schematic that.
Gent-McWilliams parameterization: 20/20 Hindsight Peter R. Gent Senior Scientist National Center for Atmospheric Research.
Impacts of Vertical Momentum Mixing in an Arctic Ocean Model Youyu Lu 1, Greg Holloway 2, Ji Lei 1 1 Bedford Institute of Oceanography 2 Institute of Ocean.
Antarctic Circumpolar Current (ACC) By: Marie McCrary.
Our water planet and our water hemisphere
Slow down of the THC and increasing hurricane activity
OCEAN RESPONSE TO AIR-SEA FLUXES Oceanic and atmospheric mixed
Advertisement Ocean Circulation in Three Dimensions
O. Melnichenko1, N. Maximenko1, and H. Sasaki2
Week 5: Thermal wind, dynamic height and Ekman flow
RAPID AND SLOW COMMUNICATION OF OVERTURNING
Ocean Circulation based on Density: Temperature and Salinity
Time mean MSLP bias (mbar) in CCSM its atmospheric component (CAM/AMIP). CCSM4 MSLP bias is weaker than CCSM3 bias in the northern subtropical maxima.
The Role of Inter-ocean Exchanges on Long-term Variability of the Northward Heat Transport in the South Atlantic Shenfu Dong CIMAS/UM and NOAA/AOML S.
(Pinet) Major ocean current systems 4 Surface patterns extend as deep as 1000 m 5.
TALLEY Copyright © 2011 Elsevier Inc. All rights reserved
What controls the time scale of Circumpolar Deep Water intrusions onto Antarctic continental shelves? Michael S. Dinniman Pierre St-Laurent John M. Klinck.
Impacts of Air-Sea Interaction on Tropical Cyclone Track and Intensity
by M. A. Srokosz, and H. L. Bryden
Tony Lee, NASA JPL/CalTech
Presentation transcript:

Role of the Southern Ocean in controlling the Atlantic meridional overturning circulation Igor Kamenkovich RSMAS, University of Miami, Miami RSMAS, University of Miami, Miami Timour Radko Naval Postgraduate School, Monterey

Motivation: The importance of the Southern Ocean for AMOC The Southern Ocean plays a key The Southern Ocean plays a key role in the global ocean circulation It is an origin and mixer for several It is an origin and mixer for several important water masses Its Antarctic Circumpolar Current Its Antarctic Circumpolar Current (ACC) acts as a connector between oceanic basins Several Southern Ocean processes are known to affect AMOC: Several Southern Ocean processes are known to affect AMOC: Winds (e.g. Toggweiler and Samuels 1995; McDermott 1996)Winds (e.g. Toggweiler and Samuels 1995; McDermott 1996) Mesoscale eddies (e.g. Gnanadesikan et al. 2003; Kamenkovich and Sarachik 2004)Mesoscale eddies (e.g. Gnanadesikan et al. 2003; Kamenkovich and Sarachik 2004) Surface buoyancy fluxes (e.g. Hasumi and Suginohara 1999, Saenko et al )Surface buoyancy fluxes (e.g. Hasumi and Suginohara 1999, Saenko et al ) All these processes determine the orientation of ACC isopycnals All these processes determine the orientation of ACC isopycnals To what degree AMOC is controlled by the ACC stratification? To what degree AMOC is controlled by the ACC stratification?

Numerical Models. Global configuration The numerical model (based on GFDL MOM, z-coordinate model): The numerical model (based on GFDL MOM, z-coordinate model): Intermediate resolution (0.5-1 degree)Intermediate resolution (0.5-1 degree) Highly idealized geometry (global and Atlantic-only)Highly idealized geometry (global and Atlantic-only) Depth is 3km (no AABW)Depth is 3km (no AABW) Vertical diffusion is m 2 sec -1Vertical diffusion is m 2 sec -1 AMOC in the global model: Streamfunction (Sv) “ Pacific ”“ Atlantic ” “ ACC ” Maximum is 20.2 Sv

Atlantic-only configuration. “Free run” Next consider the Atlantic-only model Next consider the Atlantic-only model The surface forcing and all parameters in the Atlantic are the same as in the global model The surface forcing and all parameters in the Atlantic are the same as in the global model The difference is in the lack of: The difference is in the lack of: constraint of ACC on Atlantic isopycnals volume and buoyancy exchanges between Atlantic and ACC AMOC in the Atlantic-only model “ Atlantic ” Maximum is 7.6 Sv Atlantic-only models cannot reproduce AMOC of realistic strength unless unrealistically strong diapycnal diffusion is used

Control of AMOC by ACC isopycnals Decouple Atlantic-ACC system: Decouple Atlantic-ACC system: Fix the stratification and parameterized eddy buoyancy fluxes at the Atlantic southern boundary to the values from the global run Two experiments differ by the prescribed fields: Two experiments differ by the prescribed fields: Experiment 1: Full 2D density (and geostrophic velocities) and fluxes Experiment 2: Zonally averaged density and no fluxes Experiment 2: Zonal-mean density is prescribed Experiment 1: 2D density + fluxes are prescribed 20.6 Sv 19 Sv

Effects on density Atlantic stratification is very similar between the global simulation and “ uncoupled ” Experiments 1 and 2 Atlantic stratification is very similar between the global simulation and “ uncoupled ” Experiments 1 and 2 Isopycnals are significantly shallower in the “ free ” Atlantic-only run Isopycnals are significantly shallower in the “ free ” Atlantic-only run Water is circulating along approximately the same isopycnals in all 3 simulations Shallower isopycnals correspond to weaker pressure gradients and thinner AMOC cell Atlantic isopycnals in the global run (black), Experiment 2 (red) and the “ free ” Atlantic-only run (blue)

Response to a buoyancy anomaly Experiment GW1: Adding a buoyancy anomaly in the North Atlantic slows AMOC down to 8.4 Sv in the global model Experiment GW1: Adding a buoyancy anomaly in the North Atlantic slows AMOC down to 8.4 Sv in the global model Experiment GW2: If, in the Atlantic-only model, the ACC density is prescribed to its values in the standard simulation, AMOC becomes even weaker (3.9 Sv) Experiment GW2: If, in the Atlantic-only model, the ACC density is prescribed to its values in the standard simulation, AMOC becomes even weaker (3.9 Sv) Experiment GW2: isopycnals (red) are shallower than in the global run => AMOC is even weaker Experiment GW1: Isopycnals deepen as the surface density decreases (blue contours) Overturning takes place at lighter isopycnals Atlantic isopycnals in the control run (black), Experiment GW1 (blue) and Experiment GW2 (red)

Summary and Conclusions Stratification in ACC has significant control of AMOC Stratification in ACC has significant control of AMOC The depth of the Atlantic isopycnals that outcrop in ACC is to a large degree determined at the southern boundary of the Atlantic The depth of the Atlantic isopycnals that outcrop in ACC is to a large degree determined at the southern boundary of the Atlantic The effects of the Ekman transport into the Atlantic and volume/buoyancy exchanges between the Atlantic and ACC on AMOC are indirect The effects of the Ekman transport into the Atlantic and volume/buoyancy exchanges between the Atlantic and ACC on AMOC are indirect Decrease in AMOC caused by a buoyancy anomaly in the North Atlantic is greater if the ACC density is held constant => Decrease in AMOC caused by a buoyancy anomaly in the North Atlantic is greater if the ACC density is held constant => Delayed response of the Southern Ocean to global warming can amplify the resulting AMOC weakening Delayed response of the Southern Ocean to global warming can amplify the resulting AMOC weakening We acknowledge the support by the National Science Foundation (OCE)