# R Dataset / Package DAAG / bomsoi

Attachment | Size |
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dataset-65930.csv | 12.63 KB |

## 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

### Format

This data frame contains the following columns:

- Year
a numeric vector

- Jan
average January SOI values for each year

- Feb
average February SOI values for each year

- Mar
average March SOI values for each year

- Apr
average April SOI values for each year

- May
average May SOI values for each year

- Jun
average June SOI values for each year

- Jul
average July SOI values for each year

- Aug
average August SOI values for each year

- Sep
average September SOI values for each year

- Oct
average October SOI values for each year

- Nov
average November SOI values for each year

- Dec
average December SOI values for each year

- SOI
a numeric vector consisting of average annual SOI values

- avrain
a numeric vector consisting of a weighted average annual rainfall at a large number of Australian sites

- NTrain
Northern Territory rain

- northRain
north rain

- seRain
southeast rain

- eastRain
east rain

- southRain
south rain

- swRain
southwest rain

### 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(1900:2005, y,...)) pause()# 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 plotpause()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))) pause()xbomsoi <- with(bomsoi, data.frame(SOI=SOI, cuberootRain=avrain^0.33)) xbomsoi$trendSOI <- lowess(xbomsoi$SOI)$y xbomsoi$trendRain <- lowess(xbomsoi$cuberootRain)$y rainpos <- pretty(bomsoi$avrain, 5) with(xbomsoi, {plot(cuberootRain ~ SOI, xlab = "SOI", ylab = "Rainfall (cube root scale)", yaxt="n") axis(2, at = rainpos^0.33, labels=paste(rainpos)) ## Relative changes in the two trend curves lines(lowess(cuberootRain ~ SOI)) lines(lowess(trendRain ~ trendSOI), lwd=2) }) pause()xbomsoi$detrendRain <- with(xbomsoi, cuberootRain - trendRain + mean(trendRain)) xbomsoi$detrendSOI <- with(xbomsoi, SOI - trendSOI + mean(trendSOI)) oldpar <- par(mfrow=c(1,2), pty="s") plot(cuberootRain ~ SOI, data = xbomsoi, ylab = "Rainfall (cube root scale)", yaxt="n") axis(2, at = rainpos^0.33, labels=paste(rainpos)) with(xbomsoi, lines(lowess(cuberootRain ~ SOI))) plot(detrendRain ~ detrendSOI, data = xbomsoi, xlab="Detrended SOI", ylab = "Detrended rainfall", yaxt="n") axis(2, at = rainpos^0.33, labels=paste(rainpos)) with(xbomsoi, lines(lowess(detrendRain ~ detrendSOI))) pause()par(oldpar) attach(xbomsoi) xbomsoi.ma0 <- arima(detrendRain, xreg=detrendSOI, order=c(0,0,0)) # ordinary regression modelxbomsoi.ma12 <- arima(detrendRain, xreg=detrendSOI, order=c(0,0,12)) # regression with MA(12) errors -- all 12 MA parameters are estimated xbomsoi.ma12 pause()xbomsoi.ma12s <- arima(detrendRain, xreg=detrendSOI, seasonal=list(order=c(0,0,1), period=12)) # regression with seasonal MA(1) (lag 12) errors -- only 1 MA parameter # is estimated xbomsoi.ma12s pause()xbomsoi.maSel <- arima(x = detrendRain, order = c(0, 0, 12), xreg = detrendSOI, fixed = c(0, 0, 0, NA, rep(0, 4), NA, 0, NA, NA, NA, NA), transform.pars=FALSE) # error term is MA(12) with fixed 0's at lags 1, 2, 3, 5, 6, 7, 8, 10 # NA's are used to designate coefficients that still need to be estimated # transform.pars is set to FALSE, so that MA coefficients are not # transformed (see help(arima))detach(xbomsoi) pause()Box.test(resid(lm(detrendRain ~ detrendSOI, data = xbomsoi)), type="Ljung-Box", lag=20)pause()attach(xbomsoi) xbomsoi2.maSel <- arima(x = detrendRain, order = c(0, 0, 12), xreg = poly(detrendSOI,2), fixed = c(0, 0, 0, NA, rep(0, 4), NA, 0, rep(NA,5)), transform.pars=FALSE) xbomsoi2.maSel qqnorm(resid(xbomsoi.maSel, type="normalized")) detach(xbomsoi)

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Dataset imported from https://www.r-project.org.

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