Atlantic Sea Surface Temperature Variability and its Relationship to Overlying Air Temperature, Sea Level Pressure, and 500 MB Teleconnections

Six regions of Atlantic ocean variability were identified with a rotated principal component analysis of normalized anomalies of monthly sea surface temperature for 1946-1988. The factor patterns were named: (1) Tropics, (2) Mid Atlantic, (3) Eastern Atlantic, (4) North Atlantic, (5) Southeast United States Coast (which included a smaller area around the British Isles), and (6) Caribbean to North Africa. Areas of greatest correlational significance in the 516 month data set also appeared in individual month subsets, with slight variations in location and size of the correlations. The same spatial patterns appeared when the factors were correlated to normalized anomalies of overlying air temperature. Air temperature regions tended to be slightly smaller, have somewhat smaller correlation coefficients, and were somewhat more variable in location, in both the 516 month data set and single month subsets. The six patterns were not evident in the 516 month data set or single month subsets of normalized anomalies of sea level pressure, nor were any stable patterns apparent in relation to the six factors. Spectral analysis of the six time series of factor scores revealed marginally significant periodicities within Factor 1 associated with the Southern Oscillation, and the Quasi-Biennial Oscillation. None of the other time series had atmospherically significant periods longer than two years. Factor scores were correlated to indicies of the North Atlantic Oscillation (NAO), the Southern Oscillation (SO), the Pacific/North American pattern (PNA), the East Atlantic pattern (EAtl), the West Atlantic pattern (WAtl), and the Eurasian pattern (Eurp). Some significant but small full data set correlation coefficients were found, the largest were for Factor 1 to SO and PNA, Factor 2 to NAO, Factor 4 to EAtl, and Factor 5 to Watl and Eurp. Individual month correlations were sometimes larger. Lead and lag correlations were also performed; the most significant were Factor 1 leading the SO by five to seven months, and leading the PNA by one month.