The poem contains many themes common in Yeats's poems from the 1920s including the "tower", a reference to Thoor Ballylee, which had been the title of a collection of works printed the year before "Blood and the Moon" was published, as well as the "gyre" which had been a major focus of his 1920 poem "The Second Coming".
Henry Stommel showed that the north-south gradient of the strength of the Coriolis force (the "beta effect") was responsible for the observed fact that the return flow of the slow interior gyre circulations is concentrated in fast moving western boundary currents, such as the Gulf Stream and the Kuroshio Current, a process known as western intensification.
Addition of Iron sulfate to the subarctic western Pacific gyre caused increases in primary production rates, chlorophyll a concentrations, biomass, and photosynthetic energy conversion efficiency.
Lack of this information may have doomed the thirteenth-century expedition of Vandino and Ugolino Vivaldi, who were headed towards the as yet unknown Canary Islands and were lost; once there, without understanding the Atlantic gyre and the volta do mar, they would have been unable to beat upwind to the Strait of Gibraltar and home.
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The discovery, upon which the Manila-Acapulco galleon trade was based was owing to the Spanish Andrés de Urdaneta, who, sailing in convoy under Miguel López de Legazpi, discovered the return route in 1565: the fleet split up, some heading south, but Urdaneta reasoned that the trade winds of the Pacific might move in a gyre as the Atlantic winds did.