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The impact of advection on stratification and chlorophyll variability in the equatorial Pacific
Author(s) -
Dave Apurva C.,
Lozier M. Susan
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063290
Subject(s) - advection , upwelling , stratification (seeds) , oceanography , environmental science , nutrient , phytoplankton , chlorophyll a , ecosystem , climatology , geology , ecology , biology , seed dormancy , physics , germination , botany , dormancy , thermodynamics
Previously reported global‐scale correlations between interannual variability in upper ocean stratification and chlorophyll a (a proxy for phytoplankton biomass) have been shown to be driven by strong associations between the two properties in the central and western equatorial Pacific. Herein, we present evidence that these correlations are not causal but instead result from the advection of heat, salt, and nutrients in the region. Specifically, we demonstrate that stratification and chlorophyll are simultaneously influenced by shifts in the horizontal advective inputs of cold/saline/nutrient‐rich waters from upwelling regions to the east and warm/fresh/nutrient‐poor waters to the west. We find that horizontal advection contributes substantially to the annual surface layer nutrient budget and, together with vertical advection, significantly impacts interannual variability in chlorophyll. These results highlight the importance of a three‐dimensional framework for examining nutrient supply in the upper ocean—a crucial requirement for assessing future marine ecosystem responses to a changing climate.