Home    UKAirQuality.net    Rogues Gallery    Bad NO2    Free Health Check    Links    Costs    Achievements    Profile    Geoff.Broughton@aqdm.co.uk

 Before and After

 

Here are a few examples showing the raw unscaled data (15-minutes) and then the final processed concentrations (hourly).

Does your final data look this good?

I can help you clean up your data.

Calculating the concentrations from the raw data and eliminating bad data is the very essence of air quality data processing. Making the final dataset look good can become difficult if you do not understand how instruments and calibrations can go wrong. Applying the correct sensitivity, ramping between calibrations, correcting for NOx converter inefficiencies and using stable certified gas standards is another topic all together.

NO

Large NO baseline offset, a calibration peak in June and a step change in August.

NO, NOx and NO2

NO and NOx instrument channels show regular auto-calibrations peaks and then baseline instability.

The NO2 instrument channel should always be ignored!

The after plots show the cleaned up NO and NO2 ppb concentrations.

Ozone

Regular ozone auto-calibration spans showing in the data.

 

Internal sampling between LSO visits.

SO2

Large baseline offset, zero spikes and roller coaster baseline.

PM10

TEOM instruments can show random down spikes and long periods of symmetrical noise.

Contact me Geoff.Broughton@aqdm.co.uk