Comparison of Synoptic Scale Wave Disturbances in the Tropical Western Pacific Ocean between 1972 and 1973.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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The structure and properties of the tropical easterly waves have been found to vary considerably between different regimes and time periods. This study investigates the possible roles played by the long-term sea-surface temperature SST variations in the upstream region on the waves. Time series of tropical western Pacific radiosonde data during two contrasting 8-month periods of SST anomalies, May-December 1972, which has abnormally high SST in the central and eastern Pacific, and May-December 1973 which has below normal SST in the same region are analyzed. In both periods, the waves have the same periodicity of 4-5 days and a zonal wavelength on the order of 3500 km, but the vertical phase and amplitude distributions are different as well as the thermal structures. The results suggest that SST influences the waves in two ways 1 direct effect, the warmer SST favors a better-defined warm core structure which increases the lower tropospheric wave amplitude and 2 indirect effect, the variation of SST changes the large-scale mean wind circulation which, in turn, changes the vertical structure and upper tropospheric amplitude of the waves.
- Atmospheric Physics
- Physical and Dynamic Oceanography