Subsetting HadISDH stations by Inhomogeneity Size and Frequency

We cannot yet homogenise daily or sub-daily data but there is high value in such data for studying extremes. We can use the monthly homogenisation results from the IDPHA process on HadISDH to find stations that may be of high enough quality to use for extremes studies, without homogenisation.

I have produced some code in python that can select station subsets based on a maximum allowed inhomogeneity size and maximum number of changepoints per record. I have done this for three different choices for q, T and RH.

These station subsets can be used as sub-daily station data from HadISD or gridded and assessed for regional trends.

Specific Humidity q:

< 1 g/kg and <= 3 changepoints = 1675 stations (Figure 1)
< 0.5 g/kg and <= 3 changepoints= 1500 stations (Figure 2)
< 0.1 g/kg and <= 3 changepoints = 601 stations (Figure 3)

Relative Humidity RH:

< 3 %rh and <= 3 changepoints = 1046 stations (Figure 4)
< 2 %rh and <= 3 changepoints= 695 stations (Figure 5)
< 1 %rh and <= 3 changepoints = 378 stations (Figure 6)

Temperature T:

< 1 deg C and <= 3 changepoints = 1593 stations (Figure 7)
< 0.5 deg C and <= 3 changepoints= 1309 stations (Figure 8)
< 0.1 deg C and <= 3 changepoints = 424 stations (Figure 9)

Figure 1 Specific Humidity stations with less than 1.0 g/kg maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 2 Specific Humidity stations with less than 0.5 g/kg maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 3 Specific Humidity stations with less than 0.1 g/kg maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 4 Relative Humidity stations with less than 3 %rh maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 5 Relative Humidity stations with less than 2 %rh maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 6 Relative Humidity stations with less than 1 %rh maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 7 Temperature stations with less than 1 degree C maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 8 Temperature stations with less than 0.5 degree C maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.

Figure 9 Temperature stations with less than 0.1 degree C maximum inhomogeneity size and less than or equal to 3 changepoints from HadISDH.2.0.1.2014p.