As the days lengthen and the water settles, microscopic algae near the surface multiply, and satellites see it as a change in the colour of the sea. The bloom starts in the south and on the shelves and spreads north over the open Atlantic, reaching Iceland and Norway by early summer.
Source: Data: E.U. Copernicus Marine Service, Global Ocean Colour (OCEANCOLOUR_GLO_BGC_L4_MY_009_104), gap-free daily chlorophyll from several satellites
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