Kilpatrick, T., S.-P. Xie, A. J. Miller and N. Schneider, 2018:
Satellite observations of enhanced chlorophyll variability in the
Southern California Bight
Journal of Geophysical Research-Oceans, 123, 7550-7563.
Abstract.
Satellite observations from the Moderate Resolution Imaging Spectroradiometer and
Sea-viewing Wide Field-of-view Sensor reveal a "tongue" of elevated near-surface chlorophyll that extends
into the Southern California Bight from Point Conception. A local chlorophyll maximum at the western edge
of the bight, near the Santa Rosa Ridge, indicates that the chlorophyll is not solely due to advection from
Point Conception but is enhanced by local upwelling. Chlorophyll in the bight peaks in May and June, in
phase with the seasonal cycle of wind stress curl. The spatial structure and seasonal variability suggest that
the local chlorophyll maximum is due to a combination of bathymetric influence from the Santa Rosa Ridge
and orographic influence from the coastline bend at Point Conception, which causes sharp wind stress curl
in the bight. High-resolution glider observations show thermocline doming in May–June, in support of
the local upwelling effect. Despite the evidence for local wind stress curl-forced upwelling in the bight, we
cannot rule out alternative mechanisms for the local chlorophyll maximum, such as iron supply from the
ridge. Covariability between chlorophyll, surface wind stress, and sea surface temperature (SST) indicates
that nonseasonal chlorophyll variability in the bight is closely related to SST, but the spatial patterns of
SST influence vary by time scale: Subannual chlorophyll variability is linked to local wind-forced upwelling,
while interannual chlorophyll variability is linked to large-scale SST variations over the northeast Pacific. This
suggests a greater role for nonlocal processes in the bight’s low-frequency chlorophyll variability.
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