Precipitation Patterns Associated with the High Index Phase of the Southern Oscillation

Abstract

Abstract The relationships are examined between precipitation and the high index phase of the Southern Oscillation (SO) for 19 regions of the globe which have documented low SO index-precipitation relationships (Ropelewski and Halpert 1986, 1987). The study reveals that 15 of these regions also show evidence of characteristic precipitation anomalies during the high index phase of the SO. In each of the regions, the high SO index-precipitation relationships show the opposite sign of those documented for the low index. These precipitation relationships were consistent, holding for over 70% of the high SO index years, and statistically significant. In particular, the high index phase of the SO is associated with enhanced precipitation for the monsoons of India and northern Australia as well as for the rainy seasons in northeastern South America and southeastern Africa. High SO index precipitation was found to be less than median in the central Pacific, Minicoy-Sri Lanka, eastern equatorial Africa, the Gulf o...