Response of Variability in Water Discharges from Changjiang River on PDO in Past 50 Years

Abstract

Pacific Decadal Oscillation (PDO) is a long-term ENSO-like variability of the North Pacific. The index of PDO is denoted by the first principal component of EOF of the North Pacific SST. The PDO does not only distribute the long-live trend of climate changes, but also influences evidently annual climate change (e.g. ENSO and its effect), which results in the frequency and intensity variations of ENSO. Empirical Mode Decomposition (EMD) is used to analyze the data of PDO over hundreds years (respectively 1900-2006), and obtain 8 IMF and 1 Residual, so as to find the quasi-2 and 6 yr timescales as well as quasi-15, 30 and 60 yr multi-decadal timescales. Moreover, discharges of Changjiang (Yangtze) River also occur remarkably seasonal change, quasi-2~4 timescales as well as quasi-16, 22 yr multi-decadal timescales. It is informative that the correlation index reaches 0.68 between discharge and PDO. Hence, the significant correlation is shown at the low frequency and long cycle multi-decadal timescales. It is demonstrated that PDO has a strong impact on discharge from Changjiang River at long-term multi-decadal timescales.