SEASONAL SURFACE OCEAN VARIABILITY IN THE SOUTH ATLANTIC BIGHT DERIVED FROM CZCS AND AVHRR IMAGERY

Spatial and temporal variability of sea-surface temperature (SST) and surface chlorophyll derived from the AVHRR and CZCS sensors was examin ed using a ti-year (1981-1986) time series of 866 SST and 372 CZCS ima ges 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 i s greatest in the near-shore waters and decreases offshore. Monthly me an CZCS-Chl and SST showed consistent cross-shelf gradients with near- shore surface waters cooler and more pigment-laden than offshore water s and with summer months warmer and with lower CZCS-Chl concentrations compared to winter. Harmonic regression analysis of monthly (59 month s) CZCS-Chl and SST vs time showed that the seasonal cycle explains th e highest proportion (> 80%) of CZCS-Chl variability in shelf waters f rom 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 app roximately 80-90% of the variability in the 5-year time series. Season al cycles of CZCS-Chl and SST are inversely related with the highest c orrelation observed south of Cape Hatteras and relatively poor correla tion north of Cape Hatteras. In general, the seasonal cycle explained more of the variability in near-shore and mid shelf waters than in wat ers near the shelf-break. (C) 1997 Elsevier Science Ltd.