Inter-decadal Changes in Potential Predictability of the South China Sea Summer Monsoon Intensity and Possible Causes

Inter-decadal changes in potential predictability of the South China Sea summer monsoon (SCSSM) intensity has been investigated using the signal to noise ratio method and based on the National Centers for Environmental Prediction (NCEP/NCAR) reanalysis data. The potential predictability of the SCSSM intensity underwent a significant decadal change from a low potential predictability to a high potential predictability in the 1980s, followed by a decreasing trend in the early 2000s. Further analysis shows that the inter-decadal change in potential predictability of the SCSSM intensity has a significant positive correlation with sea surface temperature (SST) of the East Indian Ocean and the Western Pacific (EIOWP). The EIOWP area averaged SST with a high (low) phase of its inter-annual variability would have strong (weak) influence on the SCSSM and hence enhance (weaken) the SCSSM signal. As a result, the potential predictability of the SCSSM intensity tends to be high (low).