# Change in temperature in Netherlands over the last century

By Wingfeet

(This article was first published on Wiekvoet, and kindly contributed to R-bloggers)

I read a post ‘race for the warmest year’ at
r4 %
mutate(.,cmtemp = cummean(TG/10))

g1 <- ggplot(r4,aes(x=daynon,y=cmtemp,
col=yearf))
g1 + geom_line(alpha=.4,show_guide=FALSE) +
scale_x_continuous(‘Day’,
breaks=mylegend\$daynon,
labels=mylegend\$month,
expand=c(0,0)) +
scale_y_continuous(‘Temperature (C)’) +
geom_line(data=r4[r4\$yearf==’2014′,],
aes(x=daynon,y=cmtemp),
col=’black’,
size=2)

#### 2014 with average of 30 years

To get a better idea how 2014 compares to previous years, the average of 30 years has been added. We had warm year, except for August, which suggested an early spring. In hindsight, second half of August had colder days than beginning April or end October.

r3\$Period <- cut(r3\$yearn,c(seq(1900,2013,30),2013,2014),
labels=c(‘1901-1930′,’1931-1960’,
‘1961-1990′,’1991-2013′,’2014’))
g1 <- ggplot(r3[r3\$yearn<2014,],aes(x=daynon,y=TG/10,col=Period))
g1 + geom_smooth(span=.15,method=’loess’,size=1.5) +
scale_x_continuous(‘Day’,
breaks=mylegend\$daynon,
labels=mylegend\$month,
expand=c(0,0)) +
geom_line(#aes(x=daynon,y=TG/10),
data=r3[r3\$yearn==2014,]) +
scale_y_continuous(‘Temperature (C)’)

#### Change by year

Finally, a plot showing how temperature changed within the years. To obtain this plot, I needed a day corrected base temperature. The baseline temperature is smoothed over days for years 1901 to 1924. The baseline was used to get a corrected baseline, which was subsequently smoothed over years and days.
Smoothers have edge effects, to remove these from the visual part, January and December have been added as extra to the data. Hence within the year there are only minimal edge effects.
The plot shows that middle last century, some parts of the year actually had a drop in temperature. In contrast, November has gradually been getting warmer since middle last century. The new century has seen quite an increase.

myyears <- r3[r3\$yearn<1925,]
m13 <- filter(myyears,daynon%
mutate(.,daynon=daynon+365)
m0 335) %>%
mutate(.,daynon=daynon-365)
myyears <- rbind_list(m0,myyears,m13)

nn <- .2
mymod <- locfit(TG ~ lp(daynon,nn=nn),
data=myyears)
topred <- data.frame(daynon=1:365)
topred\$pp <- predict(mymod,topred)
#plot(pp~ daynon,data=topred)

r5 %
mutate(.,tdiff=(TG-pp)/10) %>%
select(.,tdiff,daynon,yearn)
m13 <- filter(r5,daynon%
mutate(.,daynon=daynon+365,
yearn=yearn-1)
m0 335) %>%
mutate(.,daynon=daynon-365,
yearn=yearn+1)
r6 <- rbind_list(m0,r5,m13)

topred <- expand.grid(
daynon=seq(1:365),
yearn=1901:2014)
topred\$pp2 <- locfit(
tdiff ~ lp(yearn,daynon,nn=nn),
data=r6) %>%
predict(.,topred)
#topred <- arrange(topred,daynon,yearn)

myz <- matrix(topred\$pp2,ncol=365)
zmin <- floor(min(topred\$pp2)*10)/10
zmax <- ceiling(max(topred\$pp2)*10)/10
myseq <- seq(zmin,zmax,.1)
par(mar=c(5,4,4,6))
image(myz,useRaster=TRUE,
axes=FALSE,frame.plot=TRUE,
col=colorRampPalette(c(‘blue’,’red’))(length(myseq)-1),
breaks=myseq)
axis((seq(10,114,by=10)-1)/113,labels=seq(1910,2010,by=10),side=1)
axis((mylegend\$daynon-1)/365,labels=mylegend\$month,side=2)