Common and uncommon trends in SST and wind stress in the California and Peru–Chile current systems

Abstract

State-space models are used to estimate non-parametric long-term trends in SST and wind stress in the California Current System (CCS). Both sets of trends suggest that the CCS can be divided into three distinct geographical regions, with transitions near Point Concepcion and Cape Mendocino. Long-term changes in SST in the CCS do not appear to be caused by local long-term changes in the wind stress in the same area. Common trends in SST are estimated for the CCS, for SST in the Peru–Chile Current System (PCCS), and for the two regions combined. Four common trends are needed to describe adequately the combined dynamics. The PCCS divides into similar regions as the CCS, and the loadings on the common trends of the regions in the CCS and PCCS are related for areas with similar dynamics, e.g. upwelling areas in the two regions load together. This suggests a more global process, rather than regional dynamics, may be underlying the climate variability in both these eastern boundary current regions. These results imply that climate change will affect geographically disparate ecosystems having a common physical and ecological structure in a like manner.