It is clearly the Bermuda-Labrador Transport Index whcich is based on potential engergy anomalies (PEA) which gives an indication of the strength of the Gulf Stream and the North Atlantic Drift.
http://ioc-goos-oopc.org/state_of_the_ocean/sub/berm_lab_trans.php The Climatic Research - http://www.cru.uea.ac.uk/cru/info/thc/ - has some interesting and up to date graphics on both surface and deep flows. To quote again - 'There are three main processes that make the oceans circulate: tidal forces, wind stress, and density differences. The density of sea water is controlled by its temperature (thermo) and its salinity (haline), and the circulation driven by density differences is thus called the thermohaline circulation. The Gulf Stream (and its extension, the North Atlantic Drift) bring warm, salty water to the NE Atlantic, warming western Europe. The water cools, mixes with cold water coming from the Arctic Ocean,and becomes so dense that it sinks, both to the south and east of Greenland.' That is fairly clear - note 'mixes with cold water coming from the Arctic'. Increasing salinity due to evaporation in the Gulf Stream as water moves north - is an imporant aspect of thermo-haline circulation. The strength of the Gulf Stream - and thus the volume of cooling salty water in the North Atlantic and thus the volume of deep water formation - is influenced by interannual to multi-decadal changes in the North Atlantic Oscillation. Thermo-haline circulation is a to an extent a self sustaining process as water moves north, sinks and flows south again in the deep oceans. And you have to remember that they are not 'streams' as such - but complex and turbulent hydrodynamic flows. You seem to be arguing that the Gulf Steam and associated North Atlantic Drift is not involved in thermo-haline circulation dynamics. I think you are just playing with words for your own reasons - not showing good fath at all. On Oct 9, 12:20 am, Eric Swanson <[email protected]> wrote: > After all this discussion, I doubt that you are interested in facts. > The Gulf Stream Current, which later branches with some flowing toward > the north as the North Atlantic Drift, is not the THC. That is to > say, the rate of flow as the THC is only a fraction of the rate of > flow in the Gulf Stream as that current moves away from the US coast > off North Carolina. The PEA transport index, which you continue to > reference, does not provide a measure the THC, only the currents which > flow closer to the surface. If you will look again at Curry and > McCartney (J. Phys. Oceanogr., 2001), the graphic of Figure 12 shows > the path of the currents and the Nordic Seas aren't even on the map! > Likewise, the depth of the strongest currents, such as shown in > Figures 4 and 10, is near the surface. The THC produces the deepest > flows and much of that originates in the Arctic Mediterranean, well to > the north. thus, the PEA does not measure the THC sinking. > > Sorry, I think that it is YOU who still do not understand... > > E. S. > --------------------------------------------------------------- > On Oct 8, 6:01 am, Robert I Ellison <[email protected]> > wrote: > > > > > 'There are three main processes that make the oceans circulate: tidal > > forces, wind stress, and density differences. The density of sea water > > is controlled by its temperature (thermo) and its salinity (haline), > > and the circulation driven by density differences is thus called the > > thermohaline circulation. > > > The Gulf Stream (and its extension, the North Atlantic Drift) bring > > warm, salty water to the NE Atlantic, warming western Europe. > > The water cools, mixes with cold water coming from the Arctic Ocean, > > and becomes so dense that it sinks, both to the south and east of > > Greenland.' > > >http://www.cru.uea.ac.uk/cru/info/thc/ > > > 'The transport index is calculated as the difference in ocean > > potential energy anomaly near the centers of the subpolar and > > subtropical > > gyres. It gives an indication of the strength of the Gulf Steam and > > North Atlantic Current.' > > >http://ioc-goos-oopc.org/state_of_the_ocean/sub/berm_lab_trans.php > > > I am not clear that you know what you are talking about - how do I > > stand a hope? > > > On Sep 22, 12:31 am, Eric Swanson <[email protected]> wrote: > > > > Robert I Ellison wrote: > > > > The transport index is calculated as the difference in ocean potential > > > > energy anomaly near the centers of the subpolar and subtropical > > > > gyres. It gives an indication of the strength of the Gulf Steam and > > > > North Atlantic Current. You don't bother reading anything do you? > > > > Those currents are generally horizontal surface currents and, while > > > their strength and path do influence the weather around the North > > > Atlantic basin, they are not the same as the THC. The THC is the link > > > between the surface and the deepest portions of the world's oceans. > > > The THC is the cause of the cold temperatures and high salinities of > > > the deep layers. The paper you reference focuses on the currents > > > nearest the surface, the authors stating: > > > > "As will be seen in the discussion of the subtropical gyre below, PEA > > > changes comprise components arising from density changes directly > > > forced by surface buoyancy flux and mixing (diabatic effects), and > > > those due to the main pycnocline moving (quasi-adiabatically) up and > > > down. In the Labrador Sea, convection is typically of order 1000 m but > > > can exceed 2000 m . A weak pycnocline separates the LSW from the > > > denser Nordic seas overflow waters but contributes very little through > > > vertical movement to PEA variability..." > > > > Please notice the reference to "denser Nordic Seas overflow waters". > > > Those waters are formed by the THC process in the Arctic > > > Mediterranean. Don't you understand anything I write? > > > > E. S. > > > ---------------------------------------- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. 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