AN EMPIRICAL EIGENFUNCTION ANALYSIS OF SEA-SURFACE TEMPERATURES IN THE WESTERN NORTH-ATLANTIC

The empirical orthogonal function decomposition is used to analyze tim e records of AVHRR sea surface temperature observations of the western North Atlantic from 32.9 degrees to 43.6 degrees N, 62.7 degrees to 7 6.3 degrees W. A manually declouded dataset covering the spring of 198 5 is analyzed. The majority (80%) of the variance about the mean is ac counted for by an empirical eigenfunction, which is identified with se asonal warming, This eigenfunction shows that the shelf water, excludi ng Georges Bank, warms the most rapidly; the surface water of the Gulf of Maine warms a little less rapidly and the Gulf Stream and Sargasso Sea surface water warm the least rapidly. The SST of the Gulf Stream is also shown to behave more like that at 30 degrees N than like Sarga sso Sea water immediately to its south (similar to 35 degrees N). The second EOF is found to be a small correction to the general warming ra te described by the first EOF. The third and fourth EOFs are determine d primarily by meander propagation. Observations with partial cloud co ver from the period 1985 to 1991 are also analyzed. Again, the dominan t effect is identified as seasonal warming.