Researches On Interdecadal Changing Interaction Between Tropical Pacific And Tropical Indian Ocean By Diagnosis Analysis And Numerical Simulations

Interaction and interdecadal changing between tropical Pacific and tropical Indian Ocean have been studied using monthly NCEP/NCAR Reanalysis, GISST SST data and NCAR/CCM3. The results are summarized as follows:1. Results of SVD reveal that Indian Dipole can influence the development of El Nino to some degrees, but El Nino can influence the development of Indian Unipole. An obvious switch has been seen in 1961-1962 between the interaction of Dipole affairs and ENSO affairs, while the correlation of Unipole affairs and ENSO affairs is always distinct, no obvious chang. Before 1961, the effect of Indian Dipole affairs on ENSO affairs is weak, but after 1961, the effect is obviously enhanced.2. On the basis of discussion of the obvious interdecal changing influence of Dipole affairs on ENSO affairs, further analyses of the influence of developing ENSO affairs on Dipole affairs and interdecal variations of them show an obvious switch in 1961-1962. Before 1961, the effect of the developing ENSO affairs on Indian Dipole affairs is weak, but after 1961, the effect is obviously enhanced.3. Comparing the space-time's characteristic of tropical Indian ocean and Pacific during two different periods, the conclusion is that intensity and frequency of Dipole affairs and El Nino affairs after 1961 is stronger than that before 1961;The climatic SST field of tropical western Indian ocean and tropical eastern Pacific after 1961 is higher than that before 1961;The SST variance of tropical areas after 1961 is greater than that before 1961. And the composition of Dipole years and El Nino years for two periods shows that after 1961, the interaction between Indian Dipole affairs and El Nino affairs is distinct, but before 1961, their interaction was weak.4. The influence of tropical Indian ocean SSTA and Pacific SSTA on tropical atmospheric circulation is discussed by numerical simulation using model CCM3. After 1961, Indian Dipole affairs provides favorable condition for warm affairs of Pacific through atmospheric circulation over tropical Pacific;and warm affairs of Pacific provides favorable condition for Indian Dipole affairs through atmospheric circulation over tropical Indian ocean. The change of background of SST affects atmospheric circulation distinctly, and the intensity of tropical SSTA affairs affect atmospheric circulation to some degrees.