Bjerknes’ (1964) monograph. Data from Sverdrup (1957) & Houghton (1954) Ha+Ho Ha Ho Northward heat transport Equator Pole Heat transport: a long history of measurements…
Vonder Haar & Oort, JPO 1973. 30N 50N 70N 10N Northward heat transport Ho Ha Ha+Ho GERBE approved!
Poleward heat transport at 24ºN Pacific0.76 +/- 0.3 PW Atlantic1.2 +/- 0.3 PW Atlantic+Pacific2 +/- 0.4 PW “Across the same latitude, Ha is 1.7PW. The ocean therefore can be considered to be more important than the atmosphere at this latitude in maintaining the Earth’s budget”. Hall & Bryden, 1982; Bryden et al., 1991. NB: 1PW = 10^15 W
Trenberth & Caron, 2001 GERBE approved! (ask more to Chris D.!)
Sometimes effects of heat storage and transport are hard to disentangle Is the Gulf Stream responsible for “mild” European winters?
“Every West wind that blows crosses the Gulf Stream on its way to Europe, and carries with it a portion of this heat to temper there the Northern winds of winter. It is the influence of this stream upon climate that makes Erin the “Emerald Isle of the Sea”, and that clothes the shores of Albion in evergreen robes; while in the same latitude, on this side, the coasts of Labrador are fast bound in fetters of ice.” Maury, 1855. Eddy surface air temperature from NCAR reanalysis (January, CI=3K) WARM! COLD! Lieutenant Maury “The Pathfinder of the Seas”
Model set-up (Seager et al., 2002) Full Atmospheric model Ocean only represented as a motionless “slab” of 50m thickness, with a specified “q- flux” to represent the transport of energy by ocean currents Atmosphere
Heat storage and Climate change The surface warming due to +4Wm-2 (anthropogenic forcing) is not limited to the mixed layer… How thick is the layer is a key question to answer to predict accurately the timescale of the warming. Ho = 50m Ho = 150m Ho = 500m NB: You are welcome to download and run the model : http://sp.ph.ic.ac.uk/~arnaud
Ensemble mean model results from the IPCC-AR4 report Q1
Strength of ocean overturning at 30N (A1B Scenario + constant after yr2100) Q4
Temperature No heat exchange, only pressure effects. Salinity. No phase change in the range of observed concentration. The ocean is conservative below the surface (≈100m) layer
Conservative nature of the ocean 50km 10km 2km Spatial variations of temperature and salinity are similar on scales from several hundreds of kms to a few kms. Salinity on 1027.6 kg/m3 surface Ferrari & Polzin (2005)