Variability in chlorophyll and sea surface temperature fronts in the Long Island Sound outflow region from satellite observations

Abstract

The spatial and temporal patterns of ocean color (i.e., chlorophyll) and sea surface temperature (SST) fronts in the coastal zone of the northwest Atlantic were studied over a 2‐year period. Chlorophyll images were derived from the Sea‐viewing Wide Field‐of‐view Sensor, while SST data were obtained from the advanced very high resolution radiometer, both flying onboard Earth‐observing satellites. An edge detection algorithm was applied to each of the image sets to identify chlorophyll and thermal fronts. Persistent chlorophyll and thermal fronts co‐occurred in the same vicinity of the inner/middle shelf and were spatially congruent during second (April–May–June) and third (July–August–September) quarters and least coincident during the first (January–February–March). Calculations of the frontogenesis function showed strongest frontogenic tendencies coincident with the chlorophyll and thermal fronts. A major finding of this study was the congruence of both chlorophyll and thermal fronts at a time when the coastal current jet was the most robust, strongly suggesting that it is the presence of this jet that may be a driving force in establishing these fronts. Except for a few months per year, no clear chlorophyll enhancement was observed at thermal fronts.