What are the different Nino regions for measuring El Nino ?
A. For the measurement of strength of El Nino or La Nina the Sea Surface Temperature anomalies are measured over eastern and central Pacific Ocean at 4 different regions as depicted below graphically. These four Nino regions are bounded by NINO12 : 0-10S, 80W-90W NINO3 : 5N-5S, 90W-150W NINO4 : 5N-5S, 150W-160E NINO34 : 5N-5S, 120W-170W (Source : Climate Prediction Centre, NOAA) Q. What is Southern Oscillation Index (SOI) and ENSO A. The Southern Oscillation is the atmospheric component of El Nio. It is an oscillation in air pressure between the tropical eastern and the western Pacific Ocean waters. The strength of the Southern Oscillation is measured by the Southern Oscillation Index (SOI). The SOI is computed from fluctuations in the surface air pressure difference between Tahiti (Over Pacific Ocean) and Darwin, (Indian Ocean near Australia). El Nio episodes are associated with negative values of the SOI, meaning that the pressure at Tahiti is relatively low compared to Darwin. Low a
