Possible influence of QBO on teleconnections relating Indian summer monsoon rainfall and sea-surface temperature anomalies across the equatorial pacific

The relationship between the all-India monsoon rainfall and sea-surface temperature (SST) anomalies over different Nino regions of the equatorial Pacific Ocean have been examined from 1949 to 1995 using the full time series, as well as by grouping the seasonal rainfall and SST data according to phases of the Quasi-Biennial Oscillation (QBO) at the 50-hPa level. The results suggest that Indian monsoon rainfall shows the strongest inverse correlation with the SST anomalies over the Nino 3 region for all the seasons from the concurrent summer to the following winter. When the seasonal rainfall and SST data are stratified according to the phases of QBO, the concurrent correlations are highly enhanced during the east years of QBO over the Nino 3 region and highly reduced during the west years of QBO. This interesting result may explain the different behaviour of the Indian monsoon in different El Nino-Southern Oscillation (ENSO) years. The ENSO events continuing during the monsoon season which are associated with easterly phases of QBO are likely to cause drought, while events which are associated with westerly phases of QBO are likely to result in a normal monsoon. Copyright (C) 2002 Royal Meteorological Society.