DAAG (version 0.58)

bomsoi: Southern Oscillation Index Data

Description

The Southern Oscillation Index (SOI) is the difference in barometric pressure at sea level between Tahiti and Darwin. Annual SOI and Australian rainfall data, for the years 1900-2001, are given. Australia's annual mean rainfall is an area-weighted average of the total annual precipitation at approximately 370 rainfall stations around the country.

Usage

bomsoi

source

Australian Bureau of Meteorology web pages:

http://www.bom.gov.au/climate/change/rain02.txt and http://www.bom.gov.au/climate/current/soihtm1.shtml

References

Nicholls, N., Lavery, B., Frederiksen, C. and Drosdowsky, W. 1996. Recent apparent changes in relationships between the El Nino -- southern oscillation and Australian rainfall and temperature. Geophysical Research Letters 23: 3357-3360.

Examples

plot(ts(bomsoi[, 15:14], start=1900),
     panel=function(y,...)panel.smooth(1900:2001, y,...))

# Check for skewness by comparing the normal probability plots for 
# different a, e.g.
par(mfrow = c(2,3))
for (a in c(50, 100, 150, 200, 250, 300))
qqnorm(log(bomsoi[, "avrain"] - a))
  # a = 250 leads to a nearly linear plot
par(mfrow = c(1,1))

plot(bomsoi$SOI, log(bomsoi$avrain - 250), xlab = "SOI",
     ylab = "log(avrain = 250)")
lines(lowess(bomsoi$SOI)$y, lowess(log(bomsoi$avrain - 250))$y, lwd=2)
  # NB: separate lowess fits against time
lines(lowess(bomsoi$SOI, log(bomsoi$avrain - 250)))

detsoi <- data.frame(
  detSOI = bomsoi[, "SOI"] - lowess(bomsoi[, "SOI"])$y,
  detrain = log(bomsoi$avrain - 250) - lowess(log(bomsoi$avrain - 250))$y)
row.names(detsoi) <- paste(1900:2001)

par(mfrow = c(1,2))  
plot(log(avrain-250) ~ SOI, data = bomsoi, ylab = 
 "log(Average rainfall - 250)")
lines(lowess(bomsoi$SOI, log(bomsoi$avrain-250)))
plot(detrain ~ detSOI, data = detsoi,
  xlab="Detrended SOI", ylab = "Detrended log(Rainfall-250)")
lines(lowess(detsoi$detrain ~ detsoi$detSOI)) 
par(mfrow = c(1,1))