at greater pressure than the total cooling, even if the external cooling/heating occur at the same pressure. As a result, internal diabatic heating/cooling due to molecular diffusion explains why laboratory experiments show evidence of circulations developing as the result of surface heating/cooling (Park and Whitehead, 2000) or even when the heating is above the cooling (Coman et al., 2006). Sandström's key (though not clearly expressed) insight, was that in such circulations, the circulation as a whole must transport light water downwards and dense water upwards. This means that the effect of the circulation is to increase the potential energy. Such an increase requires an external source of energy. Recent work has built on this to argue that the ocean circulation as a whole is driven by these external sources of energy, whether wind or tides, with newer work suggesting that internal sources and sinks of energy (such as those driving diffusion) are also potentially important. Honors In 1925, Sandström was elected a member of the Royal Swedish Academy of Sciences. Publications Sandstrom, J. W. (1908), Dynamische Versuche mit Meerwasser, Ann. Hydrog. Mar. Meteorol., 36, 6–23. See also Bergen School of Meteorology References Coman, M.A., R.W Griffiths, and G.O. Hughes (2006), Sandström's experiments revisited, Journal of Marine Research, Volume 64, Number 6, November 2006, pp. 783–796. 1874 births 1947 deaths Members of the Royal Swedish Academy of Sciences Swedish meteorologists Swedish oceanographers