7th Annual Summer Institute

and

Friday Harbor Laboratory Centennial Symposium

How Does Ocean Circulation Matter for Climate Change?

Sept. 14-17, 2008

Friday Harbor Laboratories, San Juan Island, WA

The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt. On occasion, it is mistaken to mean the meridional overturning circulation (often abbreviated as MOC), but is distinct from it in two ways. Firstly, the MOC only occurs around the meridian - hence the name - and so is confined to the Atlantic Ocean. Secondly, there is published data on the MOC's existence, whilst the thermohaline circulation remains a purely theoretical conjecture.Wickipedia (Updated September 2, 2008)

•Volume integrate the fraction of AABW at each location

•Logarithmic Scale

•NADW 21% of the global ocean volume

•AABW 36% of the global ocean volume

•AABW has at least 1.7 times the volume of NADW

AABW and NADW Volumes (Johnson 2008)

NADW

AABW

Warming is apparent in the southern ocean

The Indian Ocean

SE Indian Ocean1994/5 & 2007

Johnson, Purkey, & Bullister (in press)

13-year time interval 2007- 1994/5

0.1C abyssal warming=0.9W/m2

4cm Sea level rise

Isolated to southern basins

The Pacific Ocean

MOC Active in Pacific, but shallow. Ocean drives fluxes to the atmosphere in the western

boundary current

MOC and Salinity

Coupled model

Ocean Only Model

Thompson and Cheng 2008

Sea Surface Height Variability and Mean Path of Kuroshio

AltimeterObservations

10 km model

Upper Ocean Heat BudgetFrom a High Resolution Ocean Model

Advection dominates (as in observationally derived budget) (Kelly et al, 2007)

Heat storage rate = surface flux + lateral flux + isotherm motion

The Atlantic Ocean

Connection between the mid and high latitudes is complex, and

linked to the atmosphere

Steve Yeager, NCAR

Stream Function

T anomaly

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Mike McCartney, WHOI

Winter 850mb Storm Track

Winter Stability of boundary layer

Winter Surface Storm Track

Booth et al, 2008

Minobe et al, Nature, 2008 (picture from the New Scientist, March, 2008)

Influence of the Gulf Stream on the troposphere

Questions from PCC discussion, August 2008

• What is the definition of the MOC? THC? Can we separate the THC and wind-driven circulation?

• How should models be used to investigate ocean circulation and its impact on climate in the past and in the future?

• How fast does the circulation adjust in the deep ocean, and how fast do the deep tracers change?

• How well do we understand paleo-circulation? Are there limits to our knowledge?

More Questions:

• What is the relative importance of tropical and mid-latitude SST variability for mid-latitude climate?

• Are ocean heat transport anomalies compensated by atmospheric heat transport anomalies?

• Can internal processes alone generate atmospheric variability?

• What background state in the atmosphere favors influence of mid-latitudes SST on the atmosphere?

• What part of the high latitudes is important to climate? South of 40S? North of 60N? Is sea-ice the key?

Schedule

• Breakfast 7:45-8:15 Monday-Wednesday

• Morning Session 8:45-12:30

• Lunch 12:30-1

• Afternoons Free

• Dinner 6-6:30

• Evening Session 7-10:30

• Monday MorningThe Ocean in the Climate System

• Monday EveningOcean Circulation in the PastPanel Discussion--Can the Ocean Circulation Change Drastically as Implied by

Paleo Data?• Tuesday Morning

Variability of Ocean Circulation, Interannual to Decadal• Tuesday Evening

The Carbon cycle, and land/ice interactions: what is the role for the oceans in future and past climate change?

Panel Discussion--What can we say confidently? What is a reasonable best guess about the role of the ocean in future climate change?

• Wednesday MorningDebate: What can models tell us about ocean circulation and climate? Summary Presentation