North Atlantic Oscillation Index

This is the North Oscillation Index, downloaded in May 2014 and processed as follows.

d <- scan("https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table")
isYear <- d > 1900
index <- d[!isYear]
year <- 1/24 + seq(d[isYear][1], by=1/12, length.out=length(index))
nao <- data.frame(year=year, index=index)

data(nao, package="ocedata")

Examples

data(nao, package="ocedata")
plot(nao$year, nao$index, xlab="Year", ylab="NAO index", type="l", col="gray")
k <- kernel("fejer", m=25, r=2)
smoothed <- kernapply(nao$index, k, circular=TRUE)
lines(nao$year, smoothed, col=2)