Macroscale variations in sea-surface temperatures in the North Pacific

Abstract

From about eight million sea-surface temperature (SST) observations taken over the North Pacific during the 20-year period from 1947 to 1966 and from corresponding sea-level pressure data, macroscale relationships with lags from 0 to 8 seasons are determined. Among topics discussed are the great conservatism of North Pacific surface temperature, the variations of autocorrelation between northern and southern halves of the ocean and among initial seasons, and the influence of the semipermanent wind systems on SST meridional profiles. Evidence for transport of water masses across and around the North Pacific gyre is found in SST lag correlations of 1 to 8 seasons. The magnitude of the indicated transport (0.2 to 0.3 knot) agrees well with mean surface current charts. It is inferred that the Pacific gyre may be accelerated, decelerated, or otherwise modified in certain years by long-lasting anomalous wind systems. The relation of the peaks or valleys in meridional SST profiles to the zonal wind distribution and to the anomalous reservoirs of heat left over from the preceding season or year is studied. Large-scale breaks in thermal regimes of the oceans's upper layer seem to occur about every 5 years, and a self-regulating ocean-atmosphere mechanism is suggested by the data. The amplitude of sea-surface temperature variations over the entire North Pacific may be as much as 1°F between two extreme years, a value which implies a difference in heat of evaporation of 47.8×1020 calories or a water equivalent of 8.14×1018 grams. Finally, some observations of the yearly average maximum speeds of the Kuroshio Current are compared with SST anomalies in the subtropics, and a remarkable inverse relationship is discovered.