cld: total cloud amount in okta dir: hourly prevailing wind direction in degree spd: hourly mean wind speed in m/s gust: hourly maximum gust in m/s temp: air temperature in degree Celsius wet: wet bulb temperature in degree Celsius dew: dew point in degree Celsius rh: relative humidity in % mslp: mean sea level pressure in hPa rf: hourly total rainfall in mm var means variable wind 0 in dir and spd means calm wind

• means incomplete data

## Loading required package: gsubfn
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The correlation among variables

M_TC[,c("MAXO3","MAXNOX","MAXNO2","MAXTEMP","MINTEMP","MAXWS","MINWS","MINRH","MAXRH","MAXWET","MINWET", "NOXVSNO2")]->a
panel.cor <- function(x, y, digits=2, prefix="", cex.cor, ...)
{
    usr <- par("usr"); on.exit(par(usr))
    par(usr = c(0, 1, 0, 1))
    r <- abs(cor(x, y))
    txt <- format(c(r, 0.123456789), digits=digits)[1]
    txt <- paste(prefix, txt, sep="")
    if(missing(cex.cor)) cex.cor <- 0.8/strwidth(txt)
    text(0.5, 0.5, txt, cex = cex.cor * r)
}

pairs(~MAXO3+MAXNOX+MAXNO2+MAXTEMP+MINTEMP+MAXWS+MINWS+MINRH+ MAXRH+ MAXWET+ MINWET+NOXVSNO2,data=a,lower.panel=panel.smooth, upper.panel=panel.cor, pch=20, main="correlation among variables (TC station)")