[ 1] In order to determine the sensitivity of coastal upwelling tracers to seasonal wind forcing and El Nino-Southern Oscillation (ENSO) off Baja California and Chile, nearshore salinity, cadmium (Cd), and nutrients phosphate, silicate, nitrate+ nitrite were monitored in surf zone waters at six locations along the North and South American coasts during 1997-2000. The clearest responses to upwelling favorable wind forcing were observed at the southern tip of Baja California (23.3degreesN) and off central- southern Chile (36.5degreesS). Upwelling tracers at 23.3degrees N were also the most sensitive to El Nino: average summer Cd and nutrient enrichments were 60% lower following El Nino than during the previous non-El Nino upwelling season. At two sites on the northern and central Chile coasts, conditions associated with El Nino resulted in salinity anomalies >1. Such large shifts in nearshore water properties suggest it may be possible to reconstruct past ENSO patterns from geochemical paleonutrient/paleosalinity proxy records preserved in nearshore archives such as mollusc or foraminifera shells.
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