Choose to enter either 'Specific Dates' or 'Specific Years'. 'Specific Dates' allow you to choose day, month and year to start and stop your analysis. 'Specific Years' will allow you to quickly choose the years of interest to you and the analysis will commence on 1st January and run until 31st December of those selected years.
This option allows you to choose the variable that is used for the y axis. The default is 'Hour', to show the diurnal trend in the y-direction. The other choices include 'Weekday' illustrating trends from working days to the weekends. 'Wind direction' will illustrate trends across eight compass point sectors and 'Wind speed' will show the trend by four quartiles using the modelled wind direction or speed from the UK air quality forecast which can be useful in identifying particular sources.