Spatial patterns of annual and interannual surface chlorophyll-a variability in the Peru–Chile Current System

Eleven years of satellite data on surface chlorophyll-a, wind, and altimetry were used to analyze the spatial and temporal variability of the phytoplankton biomass in the Peru–Chile Current System (PCCS; 10–40°S) and to examine the main mechanisms determining this variability. Multitaper Method–Singular Value Decomposition was used to identify statistically significant timescales of variability and to reconstruct their associated spatial patterns. The results indicate that wind stress and Rossby wave propagation govern the annual chlorophyll-a signal in the coastal (<200 km offshore) and transition (up to 80°W) zones. Eddy kinetic energy, which is associated with mesoscale activity, amplifies the annual chlorophyll signal off Peru (10–18°S) and central-southern Chile (30–40°S). In the adjacent oceanic zone (80–90°W), the wind stress curl controls the seasonal increase of chlorophyll-a in austral spring. The interannual chlorophyll-variability is closely associated with El Niño perturbations, which are transmitted from the coast towards the oceanic region via Rossby waves and mesoscale eddies. El Niño signals are observed first off south-central Chile and later off Peru, possibly linked to atmospheric teleconnection with the equatorial region. The ecological implications of regional chlorophyll-a variability are discussed.

► The MTM-SVD method was used to isolate the time scales of the chlorophyll of the Peru-Chile System. ► The annual scale of the chlorophyll is dominated by wind stress and Rossby wave propagation. ► The interannual scale is forced by El Niño perturbations that arrive via Rossby waves and eddies.