Station Reporting Interval

While working on a related project, the issue of station reporting interval came up.  The HadISD stations were selected to try and chose those in the ISD which reported very hour or every 3 hours.  To investigate how many of which type occurred at any year, I made the following plots.

Number of stations at each reporting interval

Proportion of stations at each reporting interval

The first plot shows the number of stations at each reporting interval.  I've included the option of 6 hourly as well.  Firstly, there is a drop in the number of active station after around 1990.  This plot shows the reporting intervals for the ~4200 "accepted" stations, i.e. those which are thought to be suitable for climatological studies.  The second plot shows how the proportion of the different reporting intervals changes.  The number of three hourly stations falls off with time, and the number of hourly stations increases.

If your application could depend on the reporting interval (or changes in it) then this may be of use.