Seasonal changes in sea surface temperature of the subtropical North Pacific during the last glaciation

Abstract

Proxy records of sea surface temperature (SST) near Hawaii in the North Pacific reveal that seasonal changes in SST increased during the Last Glacial Maximum (LGM); the August temperature was about 1°C cooler during the LGM than today, while that for February was 3°C cooler. Here we investigated the causes of the intensified glacial seasonally by considering (1) variations in local heating and cooling due to changes in orbital forcing, (2) variations in the vertical thermal structure of seawater, and (3) changes in the large-scale ocean circulation. Our results suggest that changes in the North Pacific subtropical gyre represent a more plausible cause for the intensified seasonally than the other two factors.