Seasonal surface ocean variability in the South Atlantic Bight derived from CZCS and AVHRR imagery

Abstract

Spatial and temporal variability of sea-surface temperature (SST) and surface chlorophyll derived from the AVHRR and CZCS sensors was examined using a 5-year (1981–1986) time series of 866 SST and 372 CZCS images averaged into monthly mean fields. Five-year mean CZCS-Chl and SST mean fields showed similar patterns, which closely followed the shelf and slope water bathymetry. Along-shelf surface pigment variability is greatest in the near-shore waters and decreases offshore. Monthly mean CZCS-Chl and SST showed consistent cross-shelf gradients with near-shore surface waters cooler and more pigment-laden than offshore waters and with summer months warmer and with lower CZCS-Chl concentrations compared to winter. Harmonic regression analysis of monthly (59 months) CZCS-Chl and SST vs time showed that the seasonal cycle explains the highest proportion (> 80%) of CZCS-Chl variability in shelf waters from Cape Fear, S.C. to Cape Lookout, N.C., with highest concentrations observed during colder months of the year (ca November through March). The seasonal signal also dominates SST in this region explaining approximately 80–90% of the variability in the 5-year time series. Seasonal cycles of CZCS-Chl and SST are inversely related with the highest correlation observed south of Cape Hatteras and relatively poor correlation north of Cape Hatteras. In general, the seasonal cycle explained more of the variability in near-shore and mid shelf waters than in waters near the shelf-break. © 1997 Elsevier Science Ltd