Summer’s Warm Surge in the North Pacific

Abstract

A physical mechanism is proposed for initiation of summer’s warm surge, which is a large body of surface layer water, heated by the spring and summer sun, which moves north to mid- and high latitudes near the ocean’s center starting from the western tropical North Pacific. As the sun approaches the equator from the south during January to March, the surface layer warms and the sea level rises due to thermal expansion, creating a downward slope to the north of the sea surface. Warm surface water will therefore begin to move north assuming that there is no counterbalancing force. At some point the colder surface water to the north, being unstable, will move south and cause the warm surface layer in the south to move farther north than the sun can urge it to do. Summer’s warm surge is a transient and shallow thermal circulation that occurs every year. Measurements in the western tropics of the northward slope of the sea surface, and the northward surface flow, are needed to confirm the proposed hypothesis.