Satellite data and other global gridded products provide the opportunity to study physical and biological variability at the global scale and over long time scales. We used Empirical Orthogonal Functions (EOFs) to identify the primary modes of variability of various physical and biological variables.

Global modes of climate variability were defined using a century-long record of sea surface temperatures. These global modes are related to regional climate modes such as the El Ni~no Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO), or the North Pacific Gyre Oscillation (NPGO). The time series associated with the six global modes are available (see “Data”) and updated monthly.

Synchrony of physical and biological global products with ENSO. The figure displays the first principal component of each global product (PC1, lines) overlaid on the Multivariate ENSO Index (MEI, shaded colors). The legend gives the corresponding percentage of variance explained and the correlation coefficient between each PC1 and the MEI.

We also conducted a shorter-term analysis of a suite of physical and biological variables (1993-2010). Variables include sea surface temperatures, sea level height anomalies, atmospheric sea level pressure, photosynthetically active radiation, precipitation, sea surface salinity, zonal surface currents, wind-driven upwelling velocities, and vertical temperature profiles at the equator for the physics; surface chlorophyll concentrations and primary production for the biology.

The analysis revealed synchronous variations associated with ENSO (first mode) and with ENSO Modoki and the NPGO (second mode). The processes driving biological variability were found to be primarily changes in the depth of the nutricline for the first mode (ENSO) and changes in advection and precipitation for the second mode (ENSO Modoki / NPGO).

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Messié, M., and F.P. Chavez. 2013. Physical-biological synchrony in the global ocean associated with recent variability in the central and western equatorial Pacific. Journal of Geophysical Research, 118: 3782–3794.

Messié, M., and F.P. Chavez. 2012. A global analysis of ENSO synchrony: The oceans' biological response to physical forcing. Journal of Geophyiscal Research, 117(C9): 1–19.

Messié, M., and F.P. Chavez. 2011. Global modes of sea surface temperature variability in relation to regional climate indices. Journal of Climate, 24: 4314–4331.

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