Description of the Summary Plot

The Summary Plot data tool provides detailed time series plots for a single site for one or several atmospheric pollutants over a user selected time range. This output is very useful as an initial check on the selected data set before further analysis is carried out using other functions.

The pollutants measured at each site are shown in the variables box once a site has been selected from the drop-down list of site names at the top of the page. Pollutant summaries can only be plotted for one site at a time. The number of pollutants measured at each site varies across the network. Multiple pollutants can be selected/de-selected by pressing and holding the CTRL key whilst highlighting the desired pollutants using the left mouse button. Modelled wind speed and wind direction from the UK air quality forecast are available in the variables list along with the pollutants and can be selected in the same way. Up to 10 variables can be selected for plotting, any more than this often results in overlapping labels on the plot. For greater control of the plot output there is the option to download the data selected as an R data object, suitable for importing straight into R for further analysis.

The period of dates over which data is available is site-dependent and shown in the greyed-out block below the date range. This is set as the default the date range. For multiple variable selections the date range shown is, for example, the date of when the first pollutant measurement was taken to the last measurement taken at the site. Therefore the date range may not correspond to the start or end of a specific pollutant measurement at the site or the start or end of modelled meteorological data.

Data can be plotted over user defined date ranges by clicking on the drop-down lists containing the day, month and year and using these to change the start and end dates accordingly. Data can be chosen on an annual basis by selecting the 'Specific Years' option and using the year drop-down menu to alter the start and end year.

Summarise data produces two plots: (1) a time series plot for each variable, including various detailed statistics; and, (2) a histogram providing the percentage of the date range that a variable is within a particular range (e.g. concentrations, modelled wind speed or direction). The time series data are formatted so that 0 is placed at the lower part of the scale (top of the data indicator strip - the red and blue bar at the bottom of the plot) and the maximum value at the top of the graph. The blue portions of the data indicator strip show the presence of data, whereas red indicates missing data. The percentage data capture is shown in green font at the top of the plot. The daily mean values are also shown as a dark orange line scaled to cover the range in the data from zero to the maximum value over the date range. Detailed statistics are shown on the time series plot including the: number of missing points (with percentage shown in brackets), minimum, maximum, mean, median and the 95th percentile value.