standardized difference
a measure of deviation in standardized units of an individual value from a mean value where 0 represents the mean, positive units represent values above the mean, and negative units represent values below the mean
Standardized Change in Monthly Surface Air Temperature Anomaly from Previous Month
Five-Month Running Average Southern Oscillation Index
Southern Oscillation Index
North Tropical Atlantic Index and NINO3 Index
Southern Oscillation Index (SOI) and Equatorial SOI