Simulation of the tropical Pacific annual cycle with an intermediate ocean-atmosphere-land model

An intermediate ocean-atmosphere coupled model incorporated land effects is developed. It is employed to simulate and understand the annual cycle of the sea surface temperature (SST) in the tropical Pacific Ocean. Some new and important physical processes determining the annual cycle of the SST are revealed.; First, the major deficiencies of the existing intermediate atmospheric models for tropical surface winds are revealed and the important roles of cloud-longwave radiational forcing and boundary-layer thermodynamics in driving the tropical surface winds are elaborated. With the improved atmospheric model, both the climatology and interannual variations of the surface winds, SLP, and rainfall over the tropics are well reproduced.; An intermediate ocean-atmosphere coupled model is developed with the improved atmospheric model and the improved WLC95 (Wang et al. 1995) ocean model. The problems of the original WLC95 ocean model in the schemes of surface latent heat flux, entrainment parameterization and oceanic dynamics have been solved. This coupled model simulates well the climatological mean and annual cycle of the SST and the related fields in the tropical Pacific.; With a varying mixed-layer depth and more realistic environments, the influences of the various air-sea coupling processes on the SST annual cycle are quite different from those with a fixed mixed-layer depth. The effects of the wind-entrainment-SST feedback are smaller than the wind-evaporation-SST feedback due to the adjustment of the mixed-layer depth and the other complementary processes. The annual variations of surface winds are demonstrated as the primary causes for the SST annual cycle in the eastern Pacific. The effects of cloud annual variations are secondary. Surface winds impact the equatorial SST annual cycle through changing the entrainment, mixed-layer depth, meridional advection and surface latent heat fluxes.; Finally, the influences of adjacent continental monsoons on the SST climate in the tropical Pacific are assessed. The climatological mean and annual cycle of the tropical Pacific SST cannot be adequately reproduced by the regional air-sea coupling. Asian-Australian monsoons have significant influences on the mean position of the western Pacific warm-pool and the equatorial Pacific thermocline slope, but have little influences on the SST annual cycle in the eastern Pacific. (Abstract shortened by UMI.)...