The influence of tropical instability waves on phytoplankton blooms in the wake of the Marquesas Islands during 1998 and on the currents observed during the drift of the Kon‐Tiki in 1947

Abstract

During 1998, five episodes of elevated chlorophyll concentration are observed in the Pacific around the Marquesas Islands (140°W, 10°S) in SeaWiFS ocean color observations. Daily positions of geostationary satellite sea surface temperature fronts reveal the influence of the westward propagating tropical instability waves as narrow temperature fronts that extend far to the south of the equator and intersect the nutrient rich waters of the Marquesas. Because the upwelled equatorial waters are rich in iron, phytoplankton blooms are produced and are advected downstream by the South Equatorial Current. Previous studies attributed the blooms to local sources of iron and the interaction of the Marquesas with the South Equatorial Current. The satellite observations suggest that the currents that produced the phytoplankton blooms may have diverted the Kon‐Tiki southward in 1947 as described by Thor Heyerdahl.