On the Annual Cycle of the Tropical Pacific Atmosphere and Ocean

Abstract

Abstract The annual cycle in sea surface temperature (SST), surface wind and other atmospheric variables in the tropical Pacific are described. The primary data sets of SST and surface wind are derived from ship observations in the Pacific between 29°N and 29°S during the period 1946–76. The annual cycle in SST away from the equator can be attributed to the annual cycle in solar heating. However, in the eastern equatorial Pacific, the annual cycle in SST undergoes systematic longitudinal changes in phase and amplitude. Near the coast of Peru, the warmest temperatures occur during March, while further west along the equator, the warmest temperatures occur progressively later and with diminished amplitude. The annual cycle in surface wind convergence along the equator displays similar changes with longitude. The annual cycle in surface wind is dominated by the meridional migrations of the trade wind belts. Near the equator, the amplitude of the annual cycle in meridional wind is larger than that in zonal wi...