(1) Dept. of Physics & Mat. Sci., City University of Hong Kong
An analysis of the data for the last 40 years over the South China Sea (SCS) suggests that the active and inactive periods of the SCS summer monsoon (SCSSM) result from one of the following: (a) a 30-60-day oscillation propagating from the south, (b) a 10-20-day oscillation propagating into the region from either the east or the north, and (c) a combination of the two oscillations. The 30-60-day oscillation apparently comes from the Madden-Julian Oscillation that propagates along the equator. On the other hand, the 10-20-day oscillation can come either from the east, usually as an easterly-wave-type disturbance, or from the north as a midlatitude trough with frontal characteristics. Irrespective of the oscillation, an active period occurs when low-level convergence and positive relative vorticity anomaly are coupled with upper-level divergence. The reverse is true for an inactive period. In either case, the upper-level vorticity pattern appears to be irrelevant.
Submittal Information
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Johnny C L Chan
06-Jul-01-20:20:37
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Dept. of Physics & Mat. Sci., City University of Hong Kong
