In climate change discussions, everybody talks about temperature. But weather is much more than that. There is at least rain and wind as directly experienced quality, and air pressure as measurable quantity. In the Netherlands, some observation stations have more than a century of daily data on these things. The data may be broken in the sense that equipment and location can have changed. To quote: “These time series are inhomogeneous because of station relocations and changes in observation techniques. As a result, these series are not suitable for trend analysis. For climate change studies we refer to the homogenized series of monthly temperatures of De Bilt link or the Central Netherlands Temperature link.” Since I am not looking at temperature but wind, I will keep to this station’s data.
(360=north, 90=east, 180=south, 270=west, 0=calm/variable)
FHVEC Vector mean windspeed (in 0.1 m/s)
FG Daily mean windspeed (in 0.1 m/s)
FHX Maximum hourly mean windspeed (in 0.1 m/s)
FHXH Hourly division in which FHX was measured
FHN Minimum hourly mean windspeed (in 0.1 m/s)
FHNH Hourly division in which FHN was measured
FXX Maximum wind gust (in 0.1 m/s)
FXXH Hourly division in which FXX was measured
The header of the data downloaded contains this, and much more information. I am sure there are good reasons to do speed in 0.1 m/s, but personally I find m/s more easy.
The two first variables are ‘vector means’. It is obvious that one cannot simply average directions. Luckily there is the circular package, which does understand direction.
Thus the data reading script becomes:
r1 <- readLines('etmgeg_235.txt')
r2 <- r1[grep('^#',r1):length(r1)]
explain <- r1[1:(grep('^#',r1)-1)]
r2 <- gsub('#','',r2)
r3 <- read.csv(text=r2)
r4 <- mutate(r3,
# Vector mean wind direction in degrees
# (360=north, 90=east, 180=south, 270=west, 0=calm/variable)
rFHVEC=FHVEC/10, # Vector mean windspeed (in 0.1 m/s)
rFG=FG/10, # Daily mean windspeed (in 0.1 m/s)
rFHX=FHX/10, # Maximum hourly mean windspeed (in 0.1 m/s)
rFHN=FHN/10, # Minimum hourly mean windspeed (in 0.1 m/s)
rFXX=FXX/10 # Maximum wind gust (in 0.1 m/s)
Plot of mean wind speed shows several effects. There is an equipment change just before year 2000. At the beginning of the curve the values are lowest, while in the sixties there is a bit more wind, as was n the nineties. I wonder about that. Is that equipment? I can imagine that hundred years ago there was lesser equipment giving such a change, but fifty or twenty years ago? Finally, close to the end of the war there is missing data.
ylab(‘Mean wind speed x (m/s)’)+